[ { "id": "https://authors.library.caltech.edu/records/qvdhx-dj150", "eprint_id": 107241, "eprint_status": "archive", "datestamp": "2023-08-19 22:48:04", "lastmod": "2023-10-23 15:40:39", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar photochemistry", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2020 American Chemical Society.", "abstract": "Solar-driven water splitting to produce renewable fuels and materials is one of the holy grails of 21st century chem. We\nhave been working on methods for the synthesis of robust mixed-metal catalysts for the oxidn. of water and other inert\nsubstrates.", "date": "2020-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20201221-125027615", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201221-125027615", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2020", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/cn8b4-nrk90", "eprint_id": 101354, "eprint_status": "archive", "datestamp": "2023-08-19 20:11:49", "lastmod": "2023-10-19 22:38:45", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "McNicholas-B-J", "name": { "family": "McNicholas", "given": "Brendon James" }, "orcid": "0000-0002-3654-681X" } ] }, "title": "Electronic structures and redox properties of boronated cyanometalates", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2020 American Chemical Society.", "abstract": "We have synthesized and structurally characterized homoleptic and heteroleptic tris(pentafluorophenyl)borane adducts of iron, ruthenium, and osmium cyanides. The III/II formal potentials are more than 2.0 V higher in the boronated octahedral complexes; and, in the boronated heteroleptic complexes, the MLCT excited triplets are relatively long-lived (he MLCT absorptions are dramatically blue-shifted).The boronated homoleptic complexes, which are electrochem. reversible, exhibit energy efficiencies of 80% in nonaq. redox flow batteries; and the boronated heteroleptic complexes exhibit cell potentials over 3.0 V in sym-rf batteries.", "date": "2020-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20200219-075302879", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200219-075302879", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2020", "author_list": "Gray, Harry B. and McNicholas, Brendon James" }, { "id": "https://authors.library.caltech.edu/records/cxrxh-6v225", "eprint_id": 101360, "eprint_status": "archive", "datestamp": "2023-08-19 20:12:29", "lastmod": "2023-10-19 22:39:13", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shin-Jieun", "name": { "family": "Shin", "given": "Jieun" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay Richmond" }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Kinetic and thermodynamic studies on T. thermophilus laccase catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2020 American Chemical Society.", "abstract": "Multicopper oxidases (MCOs) are lignin degrading enzymes with four copper sites involved in their catalysis. The consensus mechanism suggests that substrate oxidn. occurs near a type 1 Cu center (CuT1), followed by long-range electron transfer to a trinuclear Cu center (TNC) where O\u2082 is reduced to H\u2082O. Although laccases are capable of aerobic oxidn. of lignin as their primary function, the potential of CuT1 (E\u00b0(Cu\u00b2\u207a/\u207a) \u22480.5 V vs. NHE, pH 5.5) is as much as 0.5 V lower than that expected for one-electron oxidn. of polyphenolic substrates. Investigations on redox-active residues crit. for enzyme catalysis as well as reactive intermediates are crucial for elucidating this potential discrepancy and the mechanistic details of substrate oxidn. Our study focused on the MCO from a thermophilic bacterium, Thermus thermophilus HB27 (T. thermophilus Laccase) in particular (Figure 1), which is stable and active even above 90\u00b0C. Thus, thermodn. parameters assocd. with the enzyme's thermostability and improved activity at elevated temps. are of special importance. Approaches to enhancing our understanding of how the enzyme has evolved to utilize O\u2082 to degrade lignin from recalcitrant lignocellulosic substrates will be useful for developing environmentally friendly biocatalysts.", "date": "2020-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20200219-081333782", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200219-081333782", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2020", "author_list": "Shin, Jieun; Gray, Harry B.; et el." }, { "id": "https://authors.library.caltech.edu/records/4aemt-sst48", "eprint_id": 101367, "eprint_status": "archive", "datestamp": "2023-08-19 20:13:19", "lastmod": "2023-10-19 22:39:41", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Redox chemistry of metal oxos", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2020 American Chemical Society.", "abstract": "I will discuss the roles metal oxos play in two of the most important chem. reactions on planet Earth, water oxidn. to oxygen and hydrocarbon oxygenation to alcs.", "date": "2020-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20200219-085102421", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200219-085102421", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2020", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/q0f8j-6dg89", "eprint_id": 101372, "eprint_status": "archive", "datestamp": "2023-08-19 20:13:55", "lastmod": "2023-10-19 22:40:02", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Fajardo-J-Jr", "name": { "family": "Fajardo", "given": "Javier" }, "orcid": "0000-0003-0612-7953" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay Richmond" }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Spectroscopy and photophysics of tungsten arylisocyanides", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2020 American Chemical Society.", "abstract": "We report the structures and spectroscopic properties of third generation tungsten(0) arylisocyanides. These complexes exhibit very intense absorptions and strikingly bright emissions in the visible region. The lowest electronic excited states, some with microsecond lifetimes, are very strong reductants. The complexes also have large two-photon absorption cross sections (> 1000 GMs), enabling the study of near-IR-triggered photoredox chem.", "date": "2020-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20200219-101133498", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200219-101133498", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2020", "author_list": "Gray, Harry B.; Fajardo, Javier; et el." }, { "id": "https://authors.library.caltech.edu/records/yhw61-tr181", "eprint_id": 97755, "eprint_status": "archive", "datestamp": "2023-08-19 17:02:02", "lastmod": "2023-10-18 16:41:38", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electron flow through proteins", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Biol. electron transfers often occur between metal-contg. cofactors that are sepd. by very large mol. distances. Understanding the underlying physics and chem. of these electron transfer processes is the goal of much of the work in my lab. Employing laser flash-quench triggering methods, my coworkers and I have shown that 2-nm, coupling-limited Fe(II) to Ru(III) and Cu(I) to Ru(III) electron tunneling reactions in Ru-modified cytochromes and blue copper proteins occur on microsecond to nanosecond timescales. Redox equiv. can be transferred even longer distances by multistep tunneling (called hopping) through intervening tyrosines and tryptophans: notably, in our work on cytochrome P 450 and\nazurin, we have found that long-range hole hopping through intervening tryptophans can be orders of magnitude faster than single-step tunneling. Water interactions with tryptophan radical cation intermediates play key roles in promoting these hole hopping processes.", "date": "2019-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190812-092528552", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190812-092528552", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/enwb6-k8k13", "eprint_id": 97751, "eprint_status": "archive", "datestamp": "2023-08-19 17:01:36", "lastmod": "2023-10-18 16:41:01", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shin-Jieun", "name": { "family": "Shin", "given": "Jieun" } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay Richmond" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Reactive intermediates in multicopper oxidase catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "In the past few decades, there has been growing interest in using metalloenzymes for improved biomass degrdn. and utilization. Multicopper oxidases (MCOs) are lignin degrading enzymes with four copper sites (Figure 1): a type 1 Cu center (Cu_(T1)) is involved in substrate oxidn. and electron transfer to a trinuclear Cu center (TNC) where O_2 is reduced to H_2O. The MCO of interest in this study is from the HB27 strain of the thermophilic bacterium Thermus thermophilus; it is stable and active even above 90\u00b0C. The enzyme is active for lignin oxidn., although the potential of Cu_(T1) (E\u00b0(Cu2+/+) = 0.53 V vs. NHE, pH 4.5) is lower than that expected for one-electron oxidn. of methoxy phenols. It is important, therefore, to elucidate the mechanistic details of substrate oxidn. by characterizing electron-transfer pathways and trapping reactive intermediates crit. for enzyme catalysis and function. Detn. of crit. residues for enzyme catalysis as well as gaining a deeper understanding of the redox chem. involved in the catalytic pathways of MCOs will facilitate the development of more energy-efficient and environmentally friendly biocatalysts.", "date": "2019-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190812-090439146", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190812-090439146", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Shin, Jieun; Winkler, Jay Richmond; et el." }, { "id": "https://authors.library.caltech.edu/records/r70gj-kw935", "eprint_id": 98361, "eprint_status": "archive", "datestamp": "2023-08-19 15:15:48", "lastmod": "2023-10-18 17:17:38", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan Michael" }, "orcid": "0000-0001-8559-9304" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "(Nobel Laureate Signature Award for Graduate Education in Chemistry sponsored by Avantor Performance Materials) Trapping an iron(VI) water-splitting intermediate in nonaqueous media", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Understanding the mechanisms of highly-active earth-abundant water oxidn. electrocatalysts can guide the development of advanced water-splitting devices that convert renewable electricity to clean fuels and value-added products. Catalytic intermediates are difficult to isolate and characterize because they tend to be extremely transient and present at low concns. One approach to this problem is to slow down turnover by limiting the availability of the substrate. In cases where substrate and solvent are the same-such as in water oxidn.-the problem can be more complex. By dramatically limiting the availability of substrate (water and hydroxide) in nickel-iron catalyzed heterogeneous water oxidn., we have obsd. and characterized a high-valent iron intermediate. Orthogonal spectroscopies indicate that the intermediate contains iron in the rare 6+ oxidn. state. By considering this \"ferrate\" analog as a reactive intermediate, we can improve catalytic efficiency for water oxidn., and design new reactions to synthesize chems. and materials.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190830-085821545", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190830-085821545", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Hunter, Bryan Michael and Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/jvdf9-80c85", "eprint_id": 94109, "eprint_status": "archive", "datestamp": "2023-08-19 15:10:24", "lastmod": "2023-10-20 17:41:27", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Shin-Jieun", "name": { "family": "Shin", "given": "Jieun" } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay Richmond" }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Electron flow through multicopper oxidases", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "We have investigated laser-triggered electron flow through Ru-modified Thermus thermophilus laccase. The results indicate that tryptophan and tyrosine residues near the trinuclear (type 2/type 3) copper site play a key role in the catalytic cycle of the enzyme.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-095621617", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-095621617", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Gray, Harry B.; Shin, Jieun; et el." }, { "id": "https://authors.library.caltech.edu/records/xvqr1-hyp08", "eprint_id": 94108, "eprint_status": "archive", "datestamp": "2023-08-19 15:10:17", "lastmod": "2023-10-20 17:41:25", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "McNicholas-B-J", "name": { "family": "McNicholas", "given": "Brendon" }, "orcid": "0000-0002-3654-681X" }, { "id": "Despagnet-Ayoub-E", "name": { "family": "Despagnet-Ayoub", "given": "Emmanuelle" }, "orcid": "0000-0002-9013-7574" }, { "id": "Ngo-Danh-X", "name": { "family": "Ngo", "given": "Danh" } } ] }, "title": "Electronic structures and electrochemistry of boronated cyanometalates", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "We have synthesized and structurally characterized a series of organoboron-modified cyanometalates. The redn. potentials of these modified metal complexes span an exceptionally wide range, owing to variations in the electronic properties of the appended organoboron derivs. Selected highly sol. redox pairs exhibit electrochem. reversibility over a 2.1 V range in non-aq. solvents, making them excellent candidates for non-aq. redox flow batteries. Our model flow battery systems exhibit near unity Coulombic efficiencies and high energy efficiencies.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-095401293", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-095401293", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Gray, Harry B.; McNicholas, Brendon; et el." }, { "id": "https://authors.library.caltech.edu/records/3yx6y-haf04", "eprint_id": 94113, "eprint_status": "archive", "datestamp": "2023-08-19 15:10:50", "lastmod": "2023-10-20 17:42:09", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay Richmond" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Sanders-B", "name": { "family": "Sanders", "given": "Brian" } }, { "id": "Shin-Jieun", "name": { "family": "Shin", "given": "Jieun" } }, { "id": "Kielb-P-J", "name": { "family": "Kielb", "given": "Patrycja J." }, "orcid": "0000-0003-2809-0813" } ] }, "title": "Electrons, holes, protons, and proteins", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Most biol. redox transformations involve reagents with formal potentials in the \u00b11 V vs. NHE range. At the periphery of this potential window, proteins present a decidedly unsym. medium for electron transfer (ET). Whereas redn. of peptides and small arom. groups only proceeds at potentials more neg. than -2.5 V vs. NHE, one-electron oxidns. of arom. and sulfur-contg. amino-acids, as well as the peptide backbone itself, can occur at potentials in the 1.0-1.5 V vs. NHE range. This asymmetry suggests that proteins are superexchange mediators of ET in reactions of low-potential redox couples, but in high-potential redox transformations, proteins can support multistep tunneling (hopping). The sidechains of tyrosine (Tyr) and tryptophan (Trp) residues generate acidic radical cations upon oxidn. at high potentials, and several enzymes are known to utilize Tyr and Trp radicals in their catalytic mechanisms. Precise positioning of Tyr and Trp sidechains, and suitable proton acceptors, is required to provide effective redox function. A search of the protein structural database reveals that about one third of all proteins contain Tyr/Trp chains composed of three or more residues. Although these chains are distributed among all enzyme classes, they appear with greatest frequency in the oxidoreductases and hydrolases. Approx. half of the dioxygen-utilizing oxidoreductases have Tyr/Trp chain lengths of three or more residues. Our current efforts are aimed at elucidating the roles of Tyr and Trp radicals in the redox chem. of heme oxgenases and multicopper oxidases.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-102027071", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-102027071", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Winkler, Jay Richmond; Gray, Harry B.; et el." }, { "id": "https://authors.library.caltech.edu/records/xm6q9-3cv83", "eprint_id": 94091, "eprint_status": "archive", "datestamp": "2023-08-19 15:08:27", "lastmod": "2023-10-20 17:40:09", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Hole hopping through tryptophan and tyrosine chains in proteins", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Jay Winkler and I have found that most iron oxygenases have Trp/Tyr chains very near their active sites. We have suggested that an uncoupled high-valent iron-oxo enzyme intermediate would be reduced by hole transfer to the nearby residue in one of these chains. Electron transfer to the terminal residue in the chain could then protect the enzyme from oxidative degrdn.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-084510216", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-084510216", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/f87ce-3zr50", "eprint_id": 93902, "eprint_status": "archive", "datestamp": "2023-08-19 15:06:53", "lastmod": "2023-10-20 17:30:32", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Robust catalysts for solar-driven water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "The efficient generation of mol. hydrogen from sunlight and water is one of the holy grails of 21st century chem.\nHydrogen is a clean, renewable fuel that could play a key role in meeting the world's skyrocketing demand for energy.\nInvestigators in the NSF CCI Solar Fuels Program have found that Ni-Mo nanopowders and metal phosphide\nnanocrystals have catalytic efficiencies near that of platinum for hydrogen evolution from water. We also have developed robust mixed-metal nanostructured catalysts for the prodn. of oxygen from water. There is an urgent need to find even better water oxidn. catalysts, as the protons and electrons liberated when oxygen is evolved are the fundamental particles required for sustainable energy storing reactions, not only for hydrogen prodn., but also for the conversion of nitrogen and carbon dioxide to fuels and chems.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190318-074446824", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190318-074446824", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/cjfz0-1r822", "eprint_id": 90767, "eprint_status": "archive", "datestamp": "2023-08-19 10:48:54", "lastmod": "2023-10-19 14:51:08", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "McNicholas-B-J", "name": { "family": "McNicholas", "given": "Brendon J." }, "orcid": "0000-0002-3654-681X" }, { "id": "Despagnet-Ayoub-E", "name": { "family": "Despagnet-Ayoub", "given": "Emmanuelle" }, "orcid": "0000-0002-9013-7574" } ] }, "title": "Organoboron-modified cyanometalates for use in nonaqueous redox flow batteries", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "We have synthesized and structurally characterized a series of organoboron-modified cyanometalates. The redn. potentials of these modified metal complexes can be tuned over a wide range by variations in the Lewis acidities of the appended organoboron derivs. We have found half-wave potential shifts of +250 mV/BPh_3 and +380 mV/B(C_6F_5)_3, with total shifts of +1.5 and +2.1 V, resp., relative to the parent M^(III/II) (M = Mn, Fe) redox couples. Selected highly sol. complexes are attractive candidates for use in flow batteries, as their redox pairs exhibit electrochem. reversibility over a wide potential range in nonaq. solvents.", "date": "2018-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20181108-144044224", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181108-144044224", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Gray, Harry B.; McNicholas, Brendon J.; et el." }, { "id": "https://authors.library.caltech.edu/records/8h8wf-yt310", "eprint_id": 90774, "eprint_status": "archive", "datestamp": "2023-08-19 10:49:22", "lastmod": "2023-10-19 14:51:42", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Robust catalysts for solar-driven water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "The efficient generation of mol. hydrogen from sunlight and water is one of the holy grails of 21st century chem. Hydrogen is a clean, renewable fuel that could play a key role in meeting the world's skyrocketing demand for energy. Several investigators have employed hydrogenases as catalysts coupled to cathodes for H_2 prodn., as these enzymes can operate in water with very high turnover frequencies. But these enzymes are not stable under aerobic conditions, so recent work has largely focused on robust inorg. materials. Among inorg. materials, platinum is a very active catalyst for proton redn., but scarcity and high cost limit its widespread use. Clearly, we must replace platinum in solar-driven water splitting devices!. The good news is that investigators in the NSF CCI Solar Fuels Program have accepted this\nchallenge: working together, we have found that Ni-Mo nanopowders and metal phosphide nanocrystals have catalytic efficiencies near that of platinum for hydrogen evolution from water. We also have developed robust mixed-metal nanostructured catalysts for the prodn. of oxygen from water. There is an urgent need to find even better water oxidn. catalysts, as the protons and electrons liberated when oxygen is evolved are the fundamental particles required for sustainable energy storing reactions, not only for hydrogen prodn., but also for the conversion of nitrogen and carbon dioxide to fuels and chems.", "date": "2018-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20181108-161056825", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181108-161056825", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/ebkd5-kh343", "eprint_id": 90803, "eprint_status": "archive", "datestamp": "2023-08-24 00:06:25", "lastmod": "2023-10-19 14:54:18", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan" }, "orcid": "0000-0001-8559-9304" }, { "id": "Thompson-N-B", "name": { "family": "Thompson", "given": "Niklas" }, "orcid": "0000-0003-2745-4945" }, { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid" }, "orcid": "0000-0002-2785-6808" }, { "id": "Rossman-G-R", "name": { "family": "Rossman", "given": "George" }, "orcid": "0000-0002-4571-6884" }, { "id": "Hill-M-G", "name": { "family": "Hill", "given": "Michael" } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Trapping an iron(VI) water-splitting intermediate in nonaqueous media", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "Understanding the mechanisms of highly-active, earth-abundant water oxidn. electrocatalysts can guide the development of advanced water-splitting devices that convert renewable electricity to clean fuels. Unfortunately, catalytic intermediates are difficult to isolate and characterize because they tend to be extremely transient and present at low concns. A typical approach to this problem is to slow down turnover by limiting the availability of substrate. However, in cases where substrate and solvent are identical-such as in water oxidn.-the soln. can be more complex. By dramatically limiting the availability of substrate (water and hydroxide) in nickel-iron catalyzed heterogeneous water oxidn., we have\nobsd. and characterized a high-valent iron intermediate. Orthogonal spectroscopies indicate that the intermediate contains iron in the rare 6+ oxidn. state. This ferrate analog makes dioxygen upon addn. of hydroxide and can be stepwise regenerated by anodic polarization.", "date": "2018-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20181109-141642042", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181109-141642042", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Division-of-Geological-and-Planetary-Sciences" } ] }, "resource_type": "conference_item", "pub_year": "2018", "author_list": "Hunter, Bryan; Thompson, Niklas; et el." }, { "id": "https://authors.library.caltech.edu/records/rk1ez-vam87", "eprint_id": 85787, "eprint_status": "archive", "datestamp": "2023-08-19 08:03:15", "lastmod": "2023-10-18 18:47:41", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electron flow through multicopper oxidases", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "Biol. electron transfers often occur between metal-contg. cofactors that are sped. By very large mol. distances. Understanding the underlying physics and chem. of these long-range redox processes is the goal of much of the work in my lab. In collaboration with Jay Winkler, Jieun Shin, Shabnam Hematian, and Brian Sanders have investigated laser-triggered electron flow through native, mutant, and Ru-modified multicopper oxides. The results indicate that Trp and Tyr residues near the trinuclear (type 2/type 3) site play key roles during catalysis of substrate oxidsn. by these enzymes.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180412-130011500", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-130011500", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/2gv5j-jcb82", "eprint_id": 85797, "eprint_status": "archive", "datestamp": "2023-08-19 08:03:36", "lastmod": "2023-10-18 18:48:20", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Living with oxos", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "The theory of multiple bonding in metal oxos, which accounts for their ground state electronic structures and\nspectroscopic properties, predicts that an \"oxo wall\" separates Fe-Ru-Os and Co-Rh-Ir in the periodic table.\nAfter reviewing this work, I will discuss the roles metal oxos play in hydrocarbon oxygenation catalyzed by\ncytochrome P 450. Interestingly, Jay Winkler and I have found that most P450s have Trp/Tyr chains very near\nthe heme active sites. We have suggested that uncoupled high-valent iron-oxo intermediates would be reduced\nby hole transfer to these chains, thereby protecting P450s from oxidative degrdn.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180412-154951618", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-154951618", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/fzmsc-a7q40", "eprint_id": 85796, "eprint_status": "archive", "datestamp": "2023-08-19 08:03:29", "lastmod": "2023-10-18 18:48:15", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Making oxygen for space travel", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "Working with JPL, Bryan Hunter, Emmanuelle Despagnet-Ayoub, Brendon McNicholas, Jill Clinton, Mamadou Diallo, Tom\nSheridan, and Brian Sanders are exploring ways to electrocatalytically make oxygen from carbon dioxide at relatively low\ntemps. We have shown that water is a co-product of Mn (or Re) catalyzed substrate redn. to carbon monoxide. Oxidn. of\nwater liberates oxygen, as well as the protons and electrons required for sustained catalysis. We also are making robust\nmetal-carbide and metal-oxide nanoscale materials by pulsed-laser plasma synthesis with the goal of improving the\nperformance of our catalytic cathodes and anodes. We would like to have the inorg. chem. in place to make it possible (when\nneeded for space missions) to convert some fraction of carbon dioxide in the Mars atm. to oxygen.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180412-154700914", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-154700914", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/gym5e-3av19", "eprint_id": 85855, "eprint_status": "archive", "datestamp": "2023-08-19 08:05:59", "lastmod": "2023-10-18 18:53:09", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Sinclair-T-S", "name": { "family": "Sinclair", "given": "Timothy S." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Photoelectrochemical performance of BiVO_4 photoanodes integrated with [NiFe]-layered double hydroxide water oxidation nanocatalysts", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "We integrated laser-made highly active nickel iron layered double hydroxide ([NiFe]-LDH) water oxidn. nanocatalysts, which we\ndeveloped in our group, with BiVO_4 photoanodes and tested their photoelectrochem. performance under simulated sunlight\nillumination. We demonstrated decreased aggregation and increased photocurrent generation with nanocatalysts that contain\ndipos. metals ([NiFe]-LDH and cobalt oxide) as citrate surfactant selectively ligated the catalyst nanoparticles. We also\noptimized catalyst mass loading, which is a tradeoff between most efficient depletion of photogenerated holes that drive\ncatalytic turnover and parasitic light absorption by the catalyst particles. Integrated [NiFe]-LDH-BiVO_4 photoanodes enhanced\nphotocurrent generation by a factor of 3.3 compared to bare BiVO_4. Comparison of photoelectrochem. performance of\nintegrated [NiFe]-LDH-BiVO_4 photoanodes in sulfite-free aq. electrolyte with photocurrent generation of neat BiVO_4\nphotoanodes in aq. electrolyte with sulfite added as sacrificial hole acceptor showed that two thirds of all photogenerated holes\nescaped loss processes in our optimized integrated photoanodes. Our systematic integration strategies provide a path towards\nfunctional artificial photosynthesis devices.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180413-155002349", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-155002349", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Mueller, Astrid M.; Sinclair, Timothy S.; et el." }, { "id": "https://authors.library.caltech.edu/records/6sx5x-spk42", "eprint_id": 81348, "eprint_status": "archive", "datestamp": "2023-08-19 04:25:07", "lastmod": "2023-10-17 19:46:58", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Catalysts for solar-driven water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "We are working on heterogeneous inorg. catalysts that could be part of scalable solar fuel devices. We have found that\nmaterials such as Ni-Mo nanopowders and metal phosphide nanocrystals have catalytic efficiencies near that of platinum for redn. of protons in aq. solns. A major challenge is to find scalable materials that can be employed as active catalysts in integrated photoanodes for prodn. of oxygen from water, as required for the generation of protons and electrons for combination at photocathodes. We have found that mixed-metal nanosheet hydroxides made by pulsed laser ablation of precursors in water are very active water oxidn. catalysts. We are working on the structures and mechanisms of these nanosheet materials to aid in the design and construction of more efficient and robust integrated photoanodes for water splitting.", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170912-100434963", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-100434963", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/xz448-1dj10", "eprint_id": 81347, "eprint_status": "archive", "datestamp": "2023-08-19 04:25:00", "lastmod": "2023-10-17 19:46:54", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Living with oxygen", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Metal-oxos are active intermediates in reactions crit. for life on Planet Earth, water oxidn. to oxygen in photosynthesis, and oxygen redn. in respiration. The ligand field theory of metal-oxo electronic structure, which accounts for the spectroscopic and magnetic properties of these complexes, also provides a platform for discussion of their roles in the mechanisms of inorg. and biol. redox reactions.", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170912-100243787", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-100243787", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/mqtxq-9fe06", "eprint_id": 81299, "eprint_status": "archive", "datestamp": "2023-08-19 04:22:54", "lastmod": "2023-10-17 19:44:12", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hematian-S", "name": { "family": "Hematian", "given": "Shabnam" } }, { "id": "Sanders-Brian-C", "name": { "family": "Sanders", "given": "Brian C." } }, { "id": "Shin-Jieun", "name": { "family": "Shin", "given": "Jieun" } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Mechanistic investigations of a recombinant laccase from Thermus thermophilus HB27", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Laccases belong to the family of multicopper oxidases (MCOs) that couple oxidn. of a wide spectrum of substrates to the four-electron redn. of dioxygen (O_2) to water. Laccases typically contain four copper ion sites arranged in two centers: one type 1 blue copper center and one trinuclear cluster (TNC) consisting of one type 2 copper and a binuclear type 3 copper pair. Dioxygen binding, activation, and redn. are believed to proceed at the TNC with electrons delivered from the type 1 site. The precise mechanism of coupling O_2 redn. to substrate oxidn. is a subject of considerable fundamental and technol. significance. Of particular interest is the mechanism by which laccases oxidize refractory substrates such as phenols and lignin. To gain deeper insight into laccase catalysis, we have cloned the gene for a recombinant multicopper oxidase from the hyperthermophilic bacterium Thermus thermophilus HB27 (Tth-MCO), and expressed the enzyme as a 6Histagged protein in Escherichia coli. Several mutants of the recombinant enzyme have been prepd. by sitedirected mutagenesis and investigated using various structural and spectroscopic techniques. Our recent results\non the reaction pathways and intermediates involved in the enzymic reaction will be discussed.", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170911-134714732", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170911-134714732", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Hematian, Shabnam; Sanders, Brian C.; et el." }, { "id": "https://authors.library.caltech.edu/records/bye3w-65m43", "eprint_id": 77154, "eprint_status": "archive", "datestamp": "2023-08-19 02:21:47", "lastmod": "2023-10-25 21:55:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electronic structures of diplatinum complexes", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "The unusual photophys. properties of d8d8 complexes have intrigued inorg. chemists for many years. Nilay\nHazari and I (with other good friends) worked on dipalladium electronic structures during the time he was in\nthe Bercaw-Labinger group at Caltech. In my lecture in his honor, I will discuss the latest developments in the\nfield, with emphasis on work by Jay Winkler and Yan Choi Lam on diplatinum photophysics, and by Bryan\nHunter, Tania Darnton, Mike Hill, Tony Vlcek, and Standa Zalis on rare (unique) 6p-sigma-bonded complexes.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170503-105050009", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-105050009", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "collection": "CaltechAUTHORS", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/v2jx6-sxe33", "eprint_id": 77148, "eprint_status": "archive", "datestamp": "2023-08-19 02:21:05", "lastmod": "2023-10-25 21:55:17", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Metal-oxos in chemistry and biology", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "The dianionic oxo ligand occupies a very special place in coordination chem., owing to its ability to stabilize high oxidn. states of metals. My first papers on the ligand field theory of multiple bonding in metal-oxos appeared in the first vol. of Inorg. Chem. The theory, which accounts for the optical and EPR spectroscopic properties of these complexes, also predicts that there must be an \"oxo wall\" between Fe-Ru-Os and Co-Rh-Ir in the periodic table. There have been many attempts to break down the wall, but it is still in pretty good shape!. I will review this early work, then discuss the roles metal-oxos play in two of the most\nimportant chem. reactions on planet Earth, hydrocarbon oxygenation catalyzed by cytochrome P 450, and solar-driven water oxidn. catalyzed by photosystem-II. Water splitting catalyzed by inorg. materials also is of great current interest. In this area, recent work has shown that Fe(VI)-oxos likely are key intermediates in water oxidn. catalyzed by robust LDH-(Fe,Ni)-nanosheets.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170503-103335721", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-103335721", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/2zxxe-mdt18", "eprint_id": 77150, "eprint_status": "archive", "datestamp": "2023-08-19 02:21:18", "lastmod": "2023-10-25 21:55:26", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Pulsed-laser synthesis of advanced nanomaterials for water-oxidation catalysis and sunlight capture", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Conversion of solar energy into storable fuels is essential to meet future global energy demands. Efficient, robust catalysts and light absorbers that are exclusively made of non-precious elements are imperative for a sustainable energy economy. In pulsed-laser synthesis, nanoparticles are formed by very rapid cooling of a laser-induced plasma comprised of elements from the solid target and the surrounding liq. We achieved control of nanoparticle size, polydispersity, and compn. by choice of laser pulse energy and the chem. nature of the solid target or liq. medium. We have readily prepd. multi-metal nanomaterials with tailored compns. by adding metal ions into the aq. liq.; our approach allowed us to rapidly optimize highly active, robust [NiFe]-layered double hydroxide nanocatalysts for water oxidn. in base. Choice of dissolved anions mattered for zinc or copper-based nanomineral formation. We also applied our method to make mixed-metal tungsten oxide\nnanomaterials for oxidative photocatalysis in aq. acid.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170503-103650482", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-103650482", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "collection": "CaltechAUTHORS", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Mueller, Astrid M.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/gp67r-xj503", "eprint_id": 77149, "eprint_status": "archive", "datestamp": "2023-08-19 02:21:11", "lastmod": "2023-10-25 21:55:20", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Sixty years of inorganic chemistry", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "I was a graduate student at Northwestern when DIC was founded. I have witnessed great advances in our field over the the last sixty years. I will tell a few stories to kick off the celebration.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170503-103511240", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-103511240", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "collection": "CaltechAUTHORS", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/pp8hk-e9g17", "eprint_id": 77152, "eprint_status": "archive", "datestamp": "2023-08-19 02:21:33", "lastmod": "2023-10-25 21:55:35", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar fuels science", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "We and many others are designing solar-driven mol. machines that could be used on a global scale to store solar energy by splitting water into its elemental components. We are investigating the structures and mechanisms of hydrogen evolving catalysts made from Earth abundant elements such as cobalt, iron, and nickel. We also are employing pulsed laser ablation in water for synthesis of robust oxygen evolving catalysts. To aid our research, we have recruited hundreds of students to join a Solar Army whose mission is the discovery of new materials for the prodn. of solar fuels.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170503-104240786", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-104240786", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "resource_type": "conference_item", "pub_year": "2017", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/sxsq9-72p83", "eprint_id": 71599, "eprint_status": "archive", "datestamp": "2023-08-20 14:02:54", "lastmod": "2023-10-23 15:56:22", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Metal-oxos in chemistry and biology", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2016 American Chemical Society.", "abstract": "The dianionic oxo ligand occupies a very special place in coordination chem., owing to its ability to donate pi electrons to stabilize high oxidn. states of metals. My papers on the ligand field theory of multiple bonding in metal-oxos were published over 50 years ago in the first vol. of Inorg. Chem. The theory, which accounts for the optical and EPR spectroscopic properties of these complexes, also predicts that there must be an \"oxo wall\" between Fe-Ru-Os and Co-Rh-Ir in the periodic table. There have been many attempts to break down the wall, but it is still in pretty good shape!. I will review this early work, then discuss the roles metal-oxos play in two of the most important chem. reactions on planet Earth, hydrocarbon oxygenation catalyzed by cytochrome P 450, and solar-driven water oxidn. catalyzed by the Mn-Ca cluster of photosystem-II. Water splitting catalyzed by inorg. materials also is of great current interest. In this area, recent work in my lab has shown that high-valent iron-oxos likely are key intermediates in water oxidn. catalyzed by robust Fe,Ni-layered double hydroxides.", "date": "2016-10", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20161031-080025729", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161031-080025729", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/8rm2r-3m840", "eprint_id": 66114, "eprint_status": "archive", "datestamp": "2023-08-20 10:37:45", "lastmod": "2023-10-18 17:09:53", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Johnson-S-I", "name": { "family": "Johnson", "given": "Samantha I." } }, { "id": "Corona-S-L", "name": { "family": "Corona", "given": "Sydney L." } }, { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A." }, "orcid": "0000-0003-0097-5716" } ] }, "title": "DFT study of an unusual proton-relay role for Cp* in hydrogen evolution catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Understanding mechanisms of the hydrogen evolution reaction (HER) is crucial to designing efficient catalysts for the prodn.\nof solar fuels. Cp*Rh(bpy) (Cp* = \u03b7^5- pentamethylcyclopentadienyl; bpy = \u03ba^2-2,2'- bipyridyl) generates hydrogen in the\npresence of acid. However, the nature of the elementary steps leading to H-H formation has not been clear, as chem.\ncharacterization of intermediates in the catalytic reaction has been difficult to obtain. Here, we present a joint exptl.-\ncomputational study that addresses this challenge. D. functional theory (DFT) calcns. demonstrate that the catalyst first\nundergoes a 2e- redn. to form a Rh^I complex. Subsequently, in presence of acid, the Rh complex undergoes protonation at the\nCp* ligand to form a complex bearing an [\u03b7^4-Cp*H] ligand, preserving the RhI center. DFT calcns. show that this complex is\n6.8 kcal /mol more stable than the analogous Rh^(III) hydride. Following the formation of this intermediate, a second protonation\ncan be carried out which results in evolution of hydrogen and restoration of \u03b7^5-Cp*. To the best of our knowledge, these\nresults are among the first to show Cp* can serve as a proton relay in HER. New DFT results on the full mechanism for this\ncompd. will be presented, and predictions of possible improvements to the catalyst will be discussed in light of the newly\ncharacterized intermediate.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160413-110622091", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160413-110622091", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Johnson, Samantha I.; Corona, Sydney L.; et el." }, { "id": "https://authors.library.caltech.edu/records/8g4y2-0mr64", "eprint_id": 66113, "eprint_status": "archive", "datestamp": "2023-08-20 10:37:39", "lastmod": "2023-10-23 15:27:46", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan M." }, "orcid": "0000-0001-8559-9304" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" } ] }, "title": "Effect of interlayer anions on [NiFe]-LDH nanosheet water oxidation activity", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Powering the planet with sustainable, carbon-neutral fuels affects every aspect of human life. Sunlight-driven water splitting is\nan attractive soln. to provide environmentally benign hydrogen fuel. Global scalability demands that all photoelectrode and\ncatalyst materials consist of earth- abundant elements. The water oxidn. half reaction requires four coupled electron and\nproton transfer steps, for which robust and efficient electrocatalysts are needed. We have shown previously that [NiFe] - layered double hydroxide (LDH) nanosheets are highly active water oxidn. catalysts [Hunter, Blakemore, Deimund, Gray,\nWinkler, Mueller, J. Am. Chem. Soc. 2014, 136, 13118]. They were synthesized by pulsed laser ablation in liqs. (PLAL), a\nmedium-throughput method that yields small, monodisperse, surfactant- free, size and compn. controlled nanomaterials\n[Blakemore, Gray, Winkler, Mueller, A. M. ACS Catal. 2013, 3, 2497]. Our [NiFe]-LDH nanosheets are among the best earthabundant\nwater oxidn. catalysts, reaching 10 mA cm^(-2) at only 280 mV overpotential on a flat electrode in 1 M aq. KOH. We\nhave now investigated the effect of interlayer anions on water oxidn. activity. Our [NiFe]-LDH materials consisted of\nsheets of edge- shared nickel oxide octahedra, with 22 % of ferric iron substituting at nickel sites. The excess pos. charges of\nFe^(3+) substituting for Ni^(2+) were balanced by interlayer anions; water was also present in the interlayer galleries. The small\nsize (<20 nm) of our nanosheets made by PLAL allowed for complete exchange of interlayer anions simply by soaking in aq.\nsolns. We synthesized twelve materials with different interlayer anions, either by anion exchange or directly by PLAL, and\nassessed their water oxidn. activity in strong aq. base. Const.- current electrolysis data showed that the basicity of\ninterlayer anions matters for water oxidn. catalysis. The catalysts were most active and self- healing in self-buffered\ncarbonate-contg. alk. electrolyte.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160413-105235075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160413-105235075", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "resource_type": "conference_item", "pub_year": "2016", "author_list": "Hunter, Bryan M.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/yp0dq-cd218", "eprint_id": 66149, "eprint_status": "archive", "datestamp": "2023-08-20 10:38:52", "lastmod": "2023-10-18 17:12:12", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lam-Yan-Choi", "name": { "family": "Lam", "given": "Yan Choi" }, "orcid": "0000-0001-7809-4471" }, { "id": "Nielsen-R-J", "name": { "family": "Nielsen", "given": "Robert J." }, "orcid": "0000-0002-7962-0186" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A." }, "orcid": "0000-0003-0097-5716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electrochemical CO2 reduction catalyzed by Mn catalysts: DFT investigations point to strategies for overpotential reduction and activity improvement", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Exptl., [(L) Mn(CO)_3]- (where L = bis alkyl- substituted bipyridine) has been obsd. to catalyze the electrochem. redn. of CO_2 to\nCO in the presence of trifluoroethanol (TFEH). Our DFT calcns. (B3LYP- d3 with continuum solvation) of the free energies of\nreaction and activation show that the highly exergonic hydrogen bonding between TFEH and TFE (homoconjugation) plays a\ncrit. role in reaction thermodn. and kinetics. The analgous 2,2'- bipyrimidine complex is predicted to have a lower (by ca. 0.5 V)\nonset overpotential, but at the expense of max. catalytic activity. As a strategy to improve catalytic activity and onset\noverpotential, a series of 2,2'- and 4,4'- bipyrimidines with tethered alc. or phenol was examd. The major predictions were that:\n(a) PhOH is not significantly more effective than TFEH at promoting dehydroxylation, due to their similar hydrogen bond\nacidities; (b) the appended phenols are less effective at promoting catalysis than the appended alc.; and (c) inclusion of one\nappended phenol arm promotes catalytic turnover by eliminating the entropic penalty of including an external PhOH in the\ndehydroxylation TS, but inclusion of two phenol arms is detrimental because intramol. hydrogen bonding stabilizes the resting\nstate of the catalytic cycle.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160414-084344138", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160414-084344138", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Lam, Yan Choi; Nielsen, Robert J.; et el." }, { "id": "https://authors.library.caltech.edu/records/yk2yq-vc409", "eprint_id": 65897, "eprint_status": "archive", "datestamp": "2023-08-20 10:35:46", "lastmod": "2023-10-18 16:54:44", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electron flow through metalloproteins", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Understanding the underlying physics and chem. of biol. electron transfer processes is the goal of much of the work in my lab.\nEmploying laser flash-quench triggering methods, my coworkers and I have shown that long-range (1.5 to 2.5 nm) electron\ntunneling reactions in Ru-modified cytochromes and blue copper proteins occur on microsecond to nanosecond timescales.\nRedox equiv. can be transferred even longer distances by multistep tunneling (called hopping) through intervening tyrosines\nand tryptophans: notably, in our work on cytochrome P 450 and azurin, we have found that long-range hole hopping through\nintervening tryptophans can be orders of magnitude faster than single-step tunneling. Could hole hopping through Tyr/Trp\nchains protect redox enzymes from oxidative damage. Jay Winkler and I think so: by examg. the structures of P450s and many\nother oxygenases, we have identified conserved Tyr/Trp chains that could transfer holes rapidly from uncoupled high-potential\nintermediates to reductants in contact with protein surface sites.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160404-132052605", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160404-132052605", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/x40gf-e4b48", "eprint_id": 65961, "eprint_status": "archive", "datestamp": "2023-08-20 10:36:09", "lastmod": "2023-10-18 17:00:09", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electronic structures and reactions of metal-oxos", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "The dianionic oxo ligand occupies a very special place in coordination chem., owing to its ability to donate pi\nelectrons to stabilize high oxidn. states of metals. The ligand field theory of multiple bonding in metal-oxos,\nwhich was formulated over 50 years ago, predicts that there must be an \"oxo wall\" between Fe-Ru-Os and Co-\nRh-Ir in the periodic table. After reviewing early work, I will discuss the electronic structures of metal-oxo\ncomplexes that catalyze hydrocarbon oxygenation and water oxidn. reactions. In the latter area, work in my\nlab by Bryan Hunter and Astrid Mueller has shown that water oxidn. to dioxygen catalyzed by mixed-metal\nlayered double hydroxides likely involves high-valent Fe-oxo intermediates.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160406-095339421", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160406-095339421", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/n1f9w-qaj11", "eprint_id": 65817, "eprint_status": "archive", "datestamp": "2023-08-20 10:34:00", "lastmod": "2023-10-18 16:50:03", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Labinger-J-A", "name": { "family": "Labinger", "given": "Jay" }, "orcid": "0000-0002-1942-9232" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Fred Basolo and the (re)naissance of American inorganic chemistry", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "It was an Australian/British chemist, Sir Ronald Nyholm, who first spoke of a \"renaissance\" of inorg. chem.; but\nits emergence as a newly dynamic subfield, beginning in the 1950s, can be seen even more clearly in the US.\nWhile John Bailar is often credited as the \"Father of American Inorg. Chem.,\" it is arguable that Fred Basolo,\nBailar's student at Illinois, has had the most lasting impact on the dramatic growth of the field in American\nacademia. Our justification for that assertion will include comments and reminiscences from the students (one\nof them first-person!) he trained, as well as an examn. of his seminal contributions in the form of both original\nresearch and textbooks, particularly the groundbreaking 1958 work \"Mechanisms of Inorg. Reactions,\" written\nwith his Northwestern colleague Ralph Pearson, which played a central role in raising the intellectual stature of\ninorg. chem. by bringing the study of mechanism to the forefront.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160331-155214201", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160331-155214201", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Labinger, Jay and Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/zp8k4-7nr08", "eprint_id": 65849, "eprint_status": "archive", "datestamp": "2023-08-20 10:34:30", "lastmod": "2023-10-18 16:51:40", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan" }, "orcid": "0000-0001-8559-9304" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" }, { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid" }, "orcid": "0000-0002-2785-6808" } ] }, "title": "In-situ spectroscopies of mixed-metal nanosheet water oxidation catalysts made by pulsed laser ablation in liquids", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Our ability to utilize sustainable resources will be crit. in meeting the ever-increasing global energy demand in\nan eco-friendly manner. The most reliable and available source of sustainable energy is the sun. The biggest\nchallenges to its practical utilization are its intermittency on earth and unequal local energy needs. As a\nconsequence, we must find a way to convert solar energy into storable, transportable fuels. We envision a solar\nwater splitting device that produces hydrogen fuel. Subsequent functionalization with carbon dioxide will\nproduce liq. fuels that are carbon neutral upon combustion. Water oxidn., the more demanding half-reaction in\nthe water splitting process, is a key component to such a working device. Earth-abundant, efficient, and robust\nwater oxidn. catalysts need to be rationally designed based on their catalytic mechanisms. We have employed\nnovel in-situ spectroelectrochem. techniques to identify short-lived catalytic intermediates under turnover\nconditions. We recently reported [NiFe]-LDH (layered double hydroxide) nanocatalyst materials that are highly\nactive for water oxidn. [Hunter, Blakemore, Deimund, Gray, Winkler, M.ovrddot.uller, J. Soc.2014, 136, 13118]\n. Our in-situ IR, Raman, and UV-visible spectroscopic data in non-aq. solvents suggest that the LDH framework\nmay support high-valent metal species. Strategic injection of substrate indicates that this transient species is\nquenched by water. Our isotope labeling expts. have shed light on the structure of catalytic intermediates.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160401-110652850", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160401-110652850", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "resource_type": "conference_item", "pub_year": "2016", "author_list": "Hunter, Bryan; Winkler, Jay; et el." }, { "id": "https://authors.library.caltech.edu/records/swbcd-h2k65", "eprint_id": 66650, "eprint_status": "archive", "datestamp": "2023-08-20 10:42:21", "lastmod": "2023-10-18 18:40:00", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Del-Ciello-S-A", "name": { "family": "Del Ciello", "given": "Sarah A." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Mechanistic investigation of proton reduction by cobaloximes: Insight from H2 oxidation kinetics", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Cobaloximes are a class of earth- abundant proton redn. catalysts that have been known since the 1980's. Previous studies\nhave come to conflicting conclusions about the mechanism of proton redn. by these catalysts, with evidence existing for both a\nhomolytic and heterolytic mechanism. In this work, kinetic anal. of the reverse reaction is used to gain further insight.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160504-105818808", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160504-105818808", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "resource_type": "conference_item", "pub_year": "2016", "author_list": "Del Ciello, Sarah A.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/46bn6-zpe38", "eprint_id": 66395, "eprint_status": "archive", "datestamp": "2023-08-20 10:39:35", "lastmod": "2023-10-18 18:02:32", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Aguirre-Quintana-L-M", "name": { "family": "Aguirre Quintana", "given": "Luis" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay" }, "orcid": "0000-0002-4453-9716" }, { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" } ] }, "title": "Observation and reactivity studies of an unusual RhI intermediate in H2 evolution catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Understanding mechanisms of hydrogen evolution is important for improving catalysts that generate clean fuels. Catalysts\noften operate via unknown mechanism(s) due to the difficulty of observing or isolating key intermediates in the 2e-/2H+ redn.\nprocess. For our study, we prepd. a family of RhI complexes bearing the pentamethylcyclopentadienyl (\u03b75-Cp*) ligand in\naddn. to derivs. of 4,4'- bipyridyl or 1,10- phenanthroline (bound in the \u03ba2 mode). Under carefully chosen conditions, these\ncompds. formed intermediate species that suggest a previously unknown mechanism of H2 evolution involving protonhydride\ntautomerism driven by the Cp* ligand. This intermediate complex could be isolated in a MeCN soln., and even as a\nsolid, making it amenable to further mechanistic investigations. The intermediate species were analyzed by mass\nspectrometry, 1H NMR, and 2H NMR (NMR is NMR spectroscopy). Results will be discussed concerning the properties and\nreactivity of these active intermediates.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160422-084313796", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160422-084313796", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Aguirre Quintana, Luis; Gray, Harry; et el." }, { "id": "https://authors.library.caltech.edu/records/sjzq7-aph67", "eprint_id": 66109, "eprint_status": "archive", "datestamp": "2023-08-20 10:37:15", "lastmod": "2023-10-18 17:09:30", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Aguirre-Quintana-L-M", "name": { "family": "Aguirre Quintana", "given": "Luis M." } }, { "id": "Johnson-S-I", "name": { "family": "Johnson", "given": "Samantha I." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Proton-hydride tautomerism in hydrogen evolution catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Efficient generation of hydrogen from renewable resources requires development of catalysts that avoid deep wells and high\nbarriers. Information about such features can be obtained by chem. characterization of catalytic intermediates, but few have\nbeen obsd. to date. Here, we have mapped the energy landscape of hydrogen evolution in a 2e- + 2H+ reaction sequence by\nchem. characterization of the intermediate formed upon initial protonation. This intermediate, obtained by treatment of Cp*Rh\n(bpy) (Cp* = \u03b7^5-pentamethylcyclcopentadienyl; bpy = \u03ba^2- 2, 2'- bipyridyl) with acid, is not a hydride species but rather bears [\u03b7^4-Cp*H] as a ligand. The preserved Rh^I center can readily be protonated, leading to evolution of H_2 and reformation of \u03b7^4-Cp*\nbound to rhodium(III) . To the best of our knowledge, this is the first direct observation of a proton- relay role for the\nubiquitous Cp* ligand, which is revealed here to minimize energy barriers by enabling proton- hydride tautomerism. These\nlow barriers enable reversible catalysis; interconversion of H+ and H_2 can be achieved by minor variation of base concn. in the\nsystem. In this presentation, the energy landscape of the system will be discussed, including details from spectroscopic studies\nof the newly detected intermediate.", "date": "2016-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160413-095050455", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160413-095050455", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Blakemore, James D.; Aguirre Quintana, Luis M.; et el." }, { "id": "https://authors.library.caltech.edu/records/6d5n2-rt630", "eprint_id": 60316, "eprint_status": "archive", "datestamp": "2023-08-20 07:32:54", "lastmod": "2023-10-24 16:25:30", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Del-Ciello-S-A", "name": { "family": "Del Ciello", "given": "Sarah A." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "H2 oxidation by cobaloximes: Mechanistic insight into hydrogen evolution catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Cobaloximes are a series of macrocyclic cobalt complexes that have been shown to catalyze the hydrogen\nevolution reaction (HER) at low overpotentials. There has been much debate about the mechanism of this\nreaction, particularly with regard to H-H bond formation. As catalysts that operate close to the thermodn.\npotential, cobaloximes show some degree of reversibility, oxidizing hydrogen in the presence of base to form\nthe conjugate acid. Presented here are kinetic studies of the cobaloxime-mediated oxidn. of hydrogen in the\npresence of base. Insight into the bifurcation between homolytic and heterolytic mechanisms of cobaloximecatalyzed\nHER is gained by studying the microscopic reverse reaction.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150918-085547603", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-085547603", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Del Ciello, Sarah A.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/jj8v0-tng53", "eprint_id": 60331, "eprint_status": "archive", "datestamp": "2023-08-20 07:33:33", "lastmod": "2023-10-24 16:26:28", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan M." }, "orcid": "0000-0001-8559-9304" }, { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" } ] }, "title": "Mixed-metal nanosheet water oxidation catalysts made by pulsed-laser ablation in liquids - Part 1: Synthesis, characterization, and electrocatalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Global sustainable energy solns. remain one of the greatest challenges of the 21st century. Health and climate risks assocd. with\ncombustion of fossil fuels threaten global stability, development and national security. The sun is the most abundant and\ncleanest source of energy, but its intermittence on earth and unequal local energy needs require conversion into stored fuels.\nChem. can meet this challenge by solar-driven water splitting with earth-abundant, efficient and robust materials. Water\noxidn. is central to the prodn. of storable chem. fuels, since ample supply of cleanly, efficiently, and affordably generated\nprotons and electrons is a prerequisite for all sustainable chem. transformations. Pulsed-laser ablation in liqs. (PLAL) is a flexible\nsynthetic strategy to prep. earth-abundant, surfactant-free, mixed-metal (hydrous) oxide nanoparticle water oxidn.\ncatalysts [Blakemore, Gray, Winkler, Mueller, ACS Catal. 2013, 3, 2497]. It offers size and compn. control through multiple\ntuneable parameters (e.g. laser pulse energy and elemental content in the ablation target and liq.). With PLAL, many different\nnanocatalysts can readily be synthesized and screened for water oxidn. activity, rendering PLAL a medium-throughput method\nfor catalyst design. We prepd. a series of Ni-Fe materials and systematically varied Fe content. Oxygen evolution activity in\nbasic electrolyte increased as Fe content decreased to 22%. Addn. of Ti^(4+) and La^(3+) ions further enhanced electrocatalysis,\nreaching 10 mA cm^(-2) at 260 mV overpotential; on a flat working electrode, this is the lowest overpotential to date for Fe-Ni\ncatalysts. We spectroscopically identified [Ni-Fe]-layered double hydroxide nanosheets with intercalated nitrate and water,\n[Ni_(1-x)Fe_x(OH_2)](NO_3)_y(OH)_(x-y)\u2022nH_2O, as the most active precatalyst. Higher turnover frequencies were obsd. with a\ngreater relative proportion of a 405.1 eV N 1s (XPS binding energy) species in the nanosheets [Hunter, Blakemore, Deimund,\nGray, Winkler, Mueller, J. Am. Chem. Soc. 2014, 136, 13118]. The effect of different intercalated anions on water oxidn.\nactivity was investigated.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150918-134235578", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-134235578", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Hunter, Bryan M.; Blakemore, James D.; et el." }, { "id": "https://authors.library.caltech.edu/records/jan1v-ehv03", "eprint_id": 60330, "eprint_status": "archive", "datestamp": "2023-08-20 07:33:26", "lastmod": "2023-10-24 16:26:26", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunter-B-M", "name": { "family": "Hunter", "given": "Bryan M." }, "orcid": "0000-0001-8559-9304" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "M\u00fcller-A-M", "name": { "family": "Mueller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" } ] }, "title": "Mixed-metal nanosheet water oxidation catalysts made by pulsed-laser ablation in liquids - Part 2: Mechanistic insights gained by novel in-situ spectroscopies", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Sustainable energy solns. impact every aspect of human life. National security, health, access to clean water, the extent of\nclimate change, and biodiversity all critically depend on the global availability of clean, affordable energy. The sun is our most\nabundant source of energy; more energy from sunlight strikes earth within a single hour than mankind consumes per yr. To\nsustainably power the planet, sunlight capture, charge transport, and catalysis are needed for fuel prodn. through water\nsplitting. Water oxidn. provides reducing equiv. through a complex four-electron transfer process. Sufficiently active, robust,\nearth-abundant catalysts for this important reaction are much needed yet still elusive; they will only be discovered through\nrational catalyst design guided by mechanistic insights into individual reaction steps. We recently reported highly efficient [NiFe]\n- layered double hydroxide water oxidn. nanocatalysts [Hunter, Blakemore, Deimund, Gray, Winkler, Mueller, J. 2014, 136,\n13118]. To gain mechanistic information, several in-situ electrochem. spectroscopies (i.e. IR, Raman, EPR, and x-ray absorption\nspectroscopies) have been developed, by which transient species during catalytic turnover were detected. We applied potentials\nto the catalyst nanosheets, at which in aq. electrolyte water oxidn. would occur, but instead we used non-aq. media to halt the\ncatalytic cycle; strategic injection of water led to turnover, and short-lived species could be identified. This way, we obtained\nexptl. evidence for intermediates required for efficient water oxidn.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150918-133442730", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-133442730", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Hunter, Bryan M.; Gray, Harry B.; et el." }, { "id": "https://authors.library.caltech.edu/records/dc92e-23t05", "eprint_id": 60027, "eprint_status": "archive", "datestamp": "2023-08-20 07:30:15", "lastmod": "2023-10-24 14:49:26", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Molecules, materials, and mechanisms for solar fuel production", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society.\n\n
Published - Gray_2015pPRES-37.pdf
", "abstract": "Collaborative research efforts in the NSF CCI Solar Fuels Program are focused on developing new fundamental\nunderstanding of mols. and materials that efficiently generate renewable hydrogen fuel using the energy of\nsunlight. Emphasis in these efforts is placed on a mechanistic understanding of reactions relevant to achieving\nfuel formation. Catalysis of water oxidn., the anodic half reaction of overall water splitting, is being intensely\nstudied. Pulsed laser ablation has proven to be a valuable technique for synthesis of small, surfactant-free,\nmixed-metal nanomaterials with size and compn. control. Deposition of these materials on electrodes results\nin assemblies that are highly active for water oxidn. In-situ spectroscopic studies of these assemblies are\nproviding new insights into possible mechanisms of oxygen evolution. In-situ spectroscopies are also being\napplied to investigate new trimetallic water-oxidn. catalysts. Metal oxides contg. Ni, Fe, and a third metal (M = Al, Ga, Mo, Cr) have been found to be superior in catalytic performance to the Ni-only or Ni-Fe analogs.\nUnderstanding the role of the third metal promises better understanding of the mechanism of catalysis in these\nmaterials. Exptl. cyclic voltammetry has demonstrated that fluorinated iron glyoxime complexes act as\nhydrogen evolving catalysts at modest overpotentials. Our objective is to use d. functional theory (DFT) calcns.\nand CV simulations to identify the mechanisms that are consistent with the obsd. activity. The calcd. redn.\npotentials and pKa's have allowed us to propose mechanisms for two catalyst derivs. In one case, the\nmechanism involves a single pathway through an Fe(0) intermediate and a subsequent Fe(II)-hydride\nintermediate. In a second case, a parallel pathway involving protonation of the ligand gives rise to a qual.\ndifferent electrochem. response. These mechanistic insights are guiding the synthesis of more active mol.\nelectrocatalysts.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150902-104403641", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-104403641", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "primary_object": { "basename": "Gray_2015pPRES-37.pdf", "url": "https://authors.library.caltech.edu/records/dc92e-23t05/files/Gray_2015pPRES-37.pdf" }, "resource_type": "conference_item", "pub_year": "2015", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/4nj5m-8wh64", "eprint_id": 60034, "eprint_status": "archive", "datestamp": "2023-08-20 07:30:48", "lastmod": "2023-10-24 14:49:55", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar fuels", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Investigators in the NSF CCI Solar Fuels Program are working on syntheses of light absorbers and catalysts to be\ncomponents in devices for solardriven water splitting. Catalysts both for water oxidn. to dioxygen (OER) and prot\ndihydrogen (HER) have been fully characterized. Promising HER heterogeneous catalysts include Ni- Mo nanopowd\n(Ni, Co) phosphides, which reduce protons in acidic aq. solns. with catalytic efficiencies near that of platinum. PIs\nFuels also are investigating homogeneous iron, cobalt, and nickel complexes that catalyze H2 prodn. from protic\nrelatively low overpotentials. Both exptl. and theor. work has shed light on the mechanisms of these reactions. A\nnew photoanode materials, tantalum nitrides and dinitrogen- intercalated tungsten oxide are esp. promising. Also\ntheor. and exptl. study are bismuth vanadate photoanode- catalyst materials; and, in recent work, a promising me\nsynthesis of mixed- metal- oxide water oxidn. catalysts, pulsed laser ablation in liqs. (PLAL) , has been developed. S\nnanocryst. materials, including a highly active Ni, Fe, Ln, Ti- oxide nanosheet OER catalyst, have been obtained by P.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150902-130713206", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-130713206", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/e1k26-vxb74", "eprint_id": 60319, "eprint_status": "archive", "datestamp": "2023-08-20 07:33:05", "lastmod": "2023-10-24 16:25:42", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Takematsu-Kana", "name": { "family": "Takematsu", "given": "Kana" }, "orcid": "0000-0002-2334-336X" }, { "id": "Wehlin-S", "name": { "family": "Wehlin", "given": "Sara" } }, { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wes" }, "orcid": "0000-0001-5316-260X" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Two- photon absorption spectroscopy of inorganic compounds", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Two-photon absorption spectroscopy (TPAS) is a powerful spect\nelectronic structures of excited states that are not accessible under one-p\nTPAS in microscopy and photodynamic therapy are growing, as two- pho\npenetrate biol. tissues. While there is both a fundamental and prac\nproperties of dyes and other photoactive compds., lab. studies are cons\nand optics required to cover a broad tuning range. We demonstrate h\npumped OPO system can be utilized to obtain TPA spectra of inorg. comp\nobtained TPA spectra for the ruthenium(II) bipyridyl complex, Ru(bpy)_3^(2+)\nphotoreductants. We show that this methodol. can be further extended\nmetal carbonyl compds.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150918-103225666", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-103225666", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Takematsu, Kana; Wehlin, Sara; et el." }, { "id": "https://authors.library.caltech.edu/records/f4vwg-fyj11", "eprint_id": 48477, "eprint_status": "archive", "datestamp": "2023-08-20 02:11:33", "lastmod": "2023-10-20 23:21:04", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R." } }, { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Gul-S", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "A route to bipyridine-functionalized silicon(111) surfaces has been developed which gave submonolayer surface coverage of immobilized 4-vinyl-2,2'-bipyridyl (vbpy). The remaining atop sites of the silicon surface were passivated with Me groups. The immobilized bipyridyl ligands bound metal ions, thus enabling assembly of metal complexes on the silicon surface. XPS studies demonstrated that [Cp*Rh(vbpy)Cl]Cl, [Cp*Ir(vbpy)Cl]Cl, and Ru(acac)2vbpy were assembled on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepd. with iridium, X-ray absorption spectroscopy at the Ir L_(III) edge showed an edge energy and post-edge features consistent with a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2'-bipyridyl). Cyclic voltammetry data for surfaces prepd. on highly doped, conducting silicon confirmed electroactivity of the assembled complexes.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140813-084518207", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140813-084518207", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Blakemore, James D.; Lattimer, Judith R.; et el." }, { "id": "https://authors.library.caltech.edu/records/y1aat-y4909", "eprint_id": 48354, "eprint_status": "archive", "datestamp": "2023-08-20 02:07:29", "lastmod": "2023-10-17 18:44:27", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sinclair-T-S", "name": { "family": "Sinclair", "given": "Timothy S." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" } ] }, "title": "Factors affecting bismuth vanadate photoelectrochemical performance", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Bismuth vanadate has recently emerged as a promising photoanode material for solar water splitting applications. Reports on unmodified BiVO_4 showed large variations in photocurrent generation. We prepd. BiVO_4 photoanodes with different chem. surface compns. and morphologies by electrodeposition and spin coating. We devised an electrodeposition procedure with iodide added to the plating bath; this way, we could obtain BiVO_4 films with matching thicknesses and control surface Bi/V ratios. Morphologies were quantified from scanning microscopy image anal. Smaller crystallites were synthesized by spin coating. We correlated chem. surface compn. and morphol. to photocurrent densities and obsd. trends only from bivariate data. Best photoelectrochem. performance required low surface Bi/V ratios, short distances to crystallites' edges, and crystallite areas that were small enough to provide good elec. contact to the FTO underneath yet sufficiently large to prevent mass transport limitations.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140811-152908877", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-152908877", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Sinclair, Timothy S.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/9874v-pwh63", "eprint_id": 48353, "eprint_status": "archive", "datestamp": "2023-08-20 02:07:22", "lastmod": "2023-10-17 18:44:21", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" } ] }, "title": "First-row transition metal oxide nanoparticle water oxidation catalysts made by pulsed laser ablation in liquids", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Conversion of solar energy into storable fuels, such as hydrogen from light-driven water splitting, will be the most viable future source of energy. To meet the world's energy demand, materials must be robust, based on earth-abundant elements, and efficient. We synthesized novel first-row transition metal oxide nanomaterials, using pulsed laser ablation in liqs. (PLAL). This method offers size and compn. control through many tunable exptl. parameters. Unlike electrodeposited catalysts, nanoparticles made by PLAL are suitable for mech. deposition on photoanodes in integrated solar water splitting devices. Mixed-metal materials were synthesized by adding metal ions into the aq. ablation liq. With PLAL, many different nanocatalysts can readily be prepd. and screened for water oxidn. activity. Our iron-nickel-oxygen nanocatalysts exhibited varying nickel content and cryst. phases, depending on ablation target, ion concn., and laser pulse energy. Characterization with XPS, powder x-ray diffraction, and electrochem. revealed that high amts. of jamborite nickel hydroxide in the partially cryst. nanomaterials led to highest water oxidn. activity in alk. conditions, with overpotentials of <300 mV at 10 mA cm^(-2).", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140811-152657186", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-152657186", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Blakemore, James D.; Gray, Harry B.; et el." }, { "id": "https://authors.library.caltech.edu/records/m8678-9fv45", "eprint_id": 48613, "eprint_status": "archive", "datestamp": "2023-08-20 02:15:49", "lastmod": "2023-10-17 19:29:19", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Gupta-Ayush", "name": { "family": "Gupta", "given": "Ayush" } }, { "id": "Warren-J-J", "name": { "family": "Warren", "given": "Jeffrey J." }, "orcid": "0000-0002-1747-3029" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Noncovalent immobilization of electrocatalysts for fuel production on carbon electrodes", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Assembling systems for the conversion of solar light energy into chem. fuels (i.e., artificial photosynthesis) requires the development of strategies for functionalization of electrode surfaces with catalysts. We have demonstrated that mol. catalysts for fuel-forming reactions can be immobilized on graphitic carbon electrode surfaces via noncovalent interactions. Our general approach relies on a pyrene-appended bipyridine ligand that serves as the linker between the catalysts and the surface. Immobilization of a rhodium proton-redn. catalyst and a rhenium CO_2-redn. catalyst afford electrocatalytically active assemblies. XPS and electrochem. studies confirm catalyst immobilization. Redn. of the rhodium system in the presence of p-toluenesulfonic acid results in catalytic H_2 prodn., while redn. of the rhenium system in the presence of CO_2 results in catalytic CO prodn.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140815-110039335", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-110039335", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Blakemore, James D.; Gupta, Ayush; et el." }, { "id": "https://authors.library.caltech.edu/records/ppvst-c3925", "eprint_id": 48423, "eprint_status": "archive", "datestamp": "2023-08-20 02:10:08", "lastmod": "2023-10-17 19:20:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Organometallic photoreductants", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "We have synthesized and fully characterized several tungsten arylisocyanide complexes, W(CNAr)_6, all of which exhibit intense metal-to-ligand charge transfer (MLCT) absorptions in the visible region of the spectrum. The lowest triplet excited state is emissive, with lifetimes ranging from 17 ns to 3.0 \u03bcs depending on the arylisocyanide ligand. A modular synthesis has been developed for tungsten oligoaryl isocyanide complexes whose triplet excited states, *W(CNAr)_6, are extremely powerful reductants: *W(CNAr)_6/[W(CNAr)6]+ potentials are near -2.7 V vs. Cp_2Fe/Cp_2Fe+. *W(CNAr)6 complexes rapidly reduce anthracene, benzophenone, and cobalticenium ion, thereby demonstrating that very challenging electron transfer reactions can be driven by these sensitizers. We are extending our work to include investigations of the photophysics and photochem. of closely related arylisocyanide complexes of chromium and molybdenum.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140812-135326530", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-135326530", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Sattler, Wesley; Winkler, Jay; et el." }, { "id": "https://authors.library.caltech.edu/records/pa30v-axg59", "eprint_id": 48606, "eprint_status": "archive", "datestamp": "2023-08-20 02:15:12", "lastmod": "2023-10-17 19:28:55", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hansen-M-C", "name": { "family": "Hansen", "given": "Michelle" } }, { "id": "Dasgupta-S", "name": { "family": "Dasgupta", "given": "Siddharth" }, "orcid": "0000-0002-9161-7457" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Recruiting the next generation of chemists through hands-on research experiences", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Mentoring future scientists and doing groundbreaking lab. research are not mutually exclusive. They actually strengthen each other. Our NSF Solar Fuels Center for Chem. Innovation has implemented a robust outreach program consisting of 3 components. In the Solar Energy Activities Lab (SEAL), high school and college students in our Solar Army search for robust metal-oxide materials with tools and coaching by CCI scientists. CCI investigators follow up with more advanced theor. and exptl. work on these and related materials, while gaining fresh insights and perspectives from training and guiding the students. In Juice-from-Juice, CCI scientists are training teachers to make dye-sensitized solar cells using natural pigments from fruits and vegetables. This maps well into the high school STEM curriculum by teaching fundamental concepts in chem., physics, and biol. The third program targets middle school kids from disadvantaged backgrounds who have not had much exposure to chem. By having a meaningful scientific experience before entering high school, these kids are more likely to pursue STEM careers than otherwise. We have been working with Informal Science Educational professionals, high school \"near peer\" mentors, evaluators, and local museums to provide a groundbreaking model of chem. informal science education outside the classroom. These types of symbiotic relationships are important steps toward the goal of a scientifically literate citizenry.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140815-100702535", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-100702535", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Hansen, Michelle; Dasgupta, Siddharth; et el." }, { "id": "https://authors.library.caltech.edu/records/fkrjy-s9b55", "eprint_id": 48418, "eprint_status": "archive", "datestamp": "2023-08-20 02:09:45", "lastmod": "2023-10-17 18:47:54", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar-driven water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Investigators in our NSF CCI Solar Fuels Program are working on catalysts for both water oxidn. to dioxygen (OER) and proton redn. to dihydrogen (HER). Promising HER heterogeneous catalysts include Ni-Mo and CoP, which reduce protons in aq. solns. with catalytic efficiencies near that of platinum. We also are investigating sol. iron, cobalt, and nickel complexes that catalyze dihydrogen prodn. from protic solns. at relatively low overpotentials. Employing laser flash/quench and NMR methods, we have shown that the active intermediate in cobalt-catalyzed dihydrogen evolution is a Co(II)-hydride. Among several new photoanode materials synthesized at Caltech, one that is esp. promising is dinitrogen-intercalated tungsten oxide. This 1.9 eV band gap oxide exhibits photocurrent under illumination out to 640 nm with a faradaic efficiency near unity for OER in perchloric acid solns. In other work of note, we have shown that robust metal-oxide water oxidn. catalysts can be made by pulsed laser ablation of precursors in liqs.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140812-134809714", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-134809714", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/e9kbt-jcv41", "eprint_id": 48484, "eprint_status": "archive", "datestamp": "2023-08-20 02:11:47", "lastmod": "2023-10-17 19:23:19", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Tungsten photosensitizers", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "The development of photosensitizers is of great interest due to their ability to carry out difficult inorg. and org. reactions in their excited states. We have developed a new class of homoleptic arylisocyanide tungsten photosensitizers, W(CNAr)_6, and studied their photoelectrochem. properties. A modular synthesis allows for the prodn. of a variety of oligoaryl isocyanide complexes of tungsten, all of which display intense metal-to-ligand charge transfer (MLCT) absorptions in the visible region. Their excited states, *W(CNAr)_6, are highly emissive with lifetimes ranging from 17 ns to 3.0 \u03bcs depending on the arylisocyanide ligand. *W(CNAr)_6, are extremely powerful reductants: [W(CNAr)_6]^+/*W(CNAr)_6 redn. potentials are more neg. than -2.6 V vs. Cp2Fe^+/Cp2Fe.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140813-091541691", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140813-091541691", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Sattler, Wesley; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/q3zc8-kya18", "eprint_id": 48486, "eprint_status": "archive", "datestamp": "2023-08-20 02:11:54", "lastmod": "2023-10-17 19:23:25", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sattler-A", "name": { "family": "Sattler", "given": "Aaron" } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Labinger-J-A", "name": { "family": "Labinger", "given": "Jay A." }, "orcid": "0000-0002-1942-9232" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Bercaw-J-E", "name": { "family": "Bercaw", "given": "John E." } } ] }, "title": "Upgrading light olefins by trimerization catalysis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Activation of a (phenoxy-imine) titanium tri-Me complex with one equiv. of B(C_6F_5)_3 effects the catalytic trimerization of ethylene. Stoichiometric activation with B(C_6F_5)_3 allows for mechanistic studies to be conducted, which give insight into catalyst initiation, trimerization, and decompn., and the relative rates of these processes. In addn. to ethylene, \u03b1-olefins are oligomerized with high selectivity for trimers (> 95%), of which approx. 85% are one regioisomer.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140813-091823187", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140813-091823187", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Sattler, Aaron; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/8bmst-x9508", "eprint_id": 45329, "eprint_status": "archive", "datestamp": "2023-08-19 23:41:47", "lastmod": "2023-10-26 17:56:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Marinescu-S-C", "name": { "family": "Marinescu", "given": "Smaranda C." }, "orcid": "0000-0003-2106-8971" }, { "id": "Laga-S-M", "name": { "family": "Laga", "given": "Stephanie M." } }, { "id": "Sattler-A", "name": { "family": "Sattler", "given": "Aaron" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Cobalt catalyzed hydrogen evolution and formic acid dehydrogenation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "A Co^I-triphos complex (triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane) reacts at room temp. with ptoulenesulfonic\nacid monohydrate in acetonitrile to generate hydrogen (0.5 equiv) and Co^(II) with a driving\nforce of just 30 meV/Co. Protonation of Co^I produces a transient Co^(III)-H complex that has been characterized\nby NMR spectroscopy. The Co^(III)-H intermediate decays by second-order kinetics with an inverse dependence\non acid concn. Anal. of the kinetics suggests that Co^(III)-H produces hydrogen by a dominant heterolytic\nchannel in which a highly reactive Co^(II)-H transient is generated by Co^I redn. of Co^(III)-H. The Co^I-triphos\ncomplex also reacts with excess formic acid to produce H_2 and CO_2. The mechanism of this transformation\nhas been probed electrochem. and in studies of the gas evolution kinetics.", "date": "2014-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140429-155014408", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140429-155014408", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Marinescu, Smaranda C.; Laga, Stephanie M.; et el." }, { "id": "https://authors.library.caltech.edu/records/byvvd-8rs14", "eprint_id": 45210, "eprint_status": "archive", "datestamp": "2023-08-19 23:40:25", "lastmod": "2023-10-26 17:52:12", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pribisko-M-A", "name": { "family": "Pribisko", "given": "Melanie A." } }, { "id": "Tang-Grace-A", "name": { "family": "Tang", "given": "Grace A." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" } ] }, "title": "DNA interactions with cytotoxic platinum-corrole conjugates", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "One of the great challenges in cancer treatment is the selective targeting of cancer cells over normal cells. The\nspecific nuclear penetration of functionalizable corroles introduces the possibility of targeted, efficient delivery of\ncovalently-tethered chemotherapy drugs. Indeed, previous expts. demonstrate a sulfonated corrole can act as\na carrier mol. for chemotherapeutic agents, specifically the DNA-intercalating anthracycline drug doxorubicin,\nresulting in enhanced drug cytotoxicity. Anticancer drugs due to their notorious lack of specificity for cancerous\ncells over normal cells and their need to be localized in the nucleus to be effective. Exploiting the selective\nuptake of the sulfonated corrole into the nucleus of brain metastatic prostate carcinoma by synthesizing a\nplatinum-corrole conjugate could result in a highly specific and effective treatment for this type of\nmetastases. Synthethic routes to bioactive platinum-corrole conjugates and their interactions with DNA\nwill be presented.", "date": "2014-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140425-082253626", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140425-082253626", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Pribisko, Melanie A.; Tang, Grace A.; et el." }, { "id": "https://authors.library.caltech.edu/records/34p2c-az217", "eprint_id": 41895, "eprint_status": "archive", "datestamp": "2023-08-19 21:16:02", "lastmod": "2023-10-25 14:53:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Fifty years of metal oxos", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "The ligand field theory of multiple bonding in metal-oxos predicts that there must be an \"oxo wall\" between Fe-Ru-Os and Co-\nRh-Ir in the periodic table. The wall is still in pretty good shape, even after many attempts to break it down. I will discuss early\nwork on the structures and reactivities of metal oxos as well as new developments in the field.", "date": "2013-09", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131011-111111928", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131011-111111928", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Gray, Harry" }, { "id": "https://authors.library.caltech.edu/records/k0sre-j2q59", "eprint_id": 41894, "eprint_status": "archive", "datestamp": "2023-08-19 21:15:56", "lastmod": "2023-10-25 14:53:11", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Powering the planet with solar fuel", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Mol. hydrogen has emerged as an attractive candidate for a clean, renewable fuel to meet the world's skyrocketing demand for\nenergy. Hydrogenase enzymes that contain iron and nickel cofactors evolve H_2 catalytically from water with turnover\nfrequencies as high as 9000 s^(-1) at 30 C. However, the relative instability of these enzymes under aerobic conditions has led to\nthe search for robust inorg. catalysts that can produce hydrogen from water. Platinum is an excellent catalyst for proton redn.\nand hydrogen oxidn., but scarcity and high cost limit its widespread use. Our emphasis is on heterogeneous and homogeneous\ncatalysts made from earth-abundant elements that could be part of scalable solar fuel devices. Promising heterogeneous\ncatalysts include MoS_2 and Ni-Mo, which reduce protons in aq. solns. with catalytic efficiencies near that of platinum. While\nhomogeneous catalysts typically degrade faster than their heterogeneous counterparts, mol. systems are much easier to study\nmechanistically. Cobalt complexes enable electrocatalytic prodn. of H_2 from solns. with high turnover frequencies, and kinetics\ninvestigations have established that the reactive intermediate is a Co(II)-hydride. The challenge of water oxidn. in many ways\neclipses that of proton redn. The oxidn. reaction involves the rearrangement of more protons and electrons, and fewer good\ncatalysts for the reaction exist that are made of earth-abundant materials. We have found that 3 to 5 nm metal-oxide particles\nmade by pulsed laser ablation of precursors in water are very active water oxidn. catalysts. We hope to elucidate the electronic\nstructures of these very small nanoparticles as part of a program with the goal of understanding their mechanisms.", "date": "2013-09", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131011-110858633", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131011-110858633", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/qqqc2-66g21", "eprint_id": 37869, "eprint_status": "archive", "datestamp": "2023-08-19 19:32:25", "lastmod": "2023-10-23 19:04:32", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ford-N-B", "name": { "family": "Ford", "given": "Nicole B." } }, { "id": "Yamada-Seiji", "name": { "family": "Yamada", "given": "Seiji" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Capturing protein dynamics by time-resolved spectroscopy: Folding and electron tunneling in cytochromes", "ispublished": "unpub", "full_text_status": "restricted", "abstract": "We have resolved the folding kinetics of two c-type cytochromes, one that exhibits twostate\nfolding and one that has an on-pathway folding intermediate. We resolve\nmillisecond-timescale folding by coupling time-resolved fluorescence energy transfer\n(FRET) with a continuous flow mixer. The efficiency of energy transfer between a dansyl\nlabel, attached to single-cysteine mutants, and the cytochrome heme during the folding\nprocess provides us with time-dependent distance distributions, which provide information\nabout the kinetics and mechanism of folding.We are also interested in characterizing the\npathway dependence of electron tunneling rates between metal sites in proteins. We have\nconverted a b-type cytochrome to a c-type cytochrome by covalently linking the porphyrin\nto cysteine residues. We investigate the effects of these changes to the protein structure,\ni.e., increased rigidity and potential new equatorial tunneling pathways, on the electron\ntransfer rates, measured via transient absorption, in a series of Ru-modified proteins.", "date": "2013-04-10", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130410-144330557", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130410-144330557", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Ford, Nicole B.; Yamada, Seiji; et el." }, { "id": "https://authors.library.caltech.edu/records/p2hee-67r98", "eprint_id": 41851, "eprint_status": "archive", "datestamp": "2023-08-19 19:24:30", "lastmod": "2023-10-25 14:50:34", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ford-N-B", "name": { "family": "Ford", "given": "Nicole B." } }, { "id": "Shin-Dong-Woo", "name": { "family": "Shin", "given": "Dong Woo" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Conformational dynamics of a fast folding cytochrome captured by electron transfer, time-resolved fluorescence energy transfer, and microfluidic mixing", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Cytochrome c-b_(562) belongs to an interesting family of four-helix bundle cytochromes that have nearly identical structures yet\nwidely divergent folding pathways, creating a unique opportunity to study the relationship between primary sequences and\nfolding in proteins with similar topologies. We characterize the dynamics of cytochrome c-b_(562) through a combination of\nelectron transfer and fluorescence energy transfer (FRET). The dynamics of intrachain diffusion in unfolded cytochromes\nare probed by monitoring contact quenching of a photoexcited, covalently-bound [Ru(bpy)2(IA-phen)]^(2+) dye by the heme Fe^(III).\nQuenching of the *Ru^(II) luminescence decay provides information about the electron transfer rates, which correspond to the\nrates of transient contact formation. We resolve fast folding by coupling time-resolved FRET with an ultrafast continuous flow\nmixer. FRET occurs between a small, covalently-bound dansyl fluorophore and the heme. Fitting the dansyl fluorescence decay\nfollowing picosecond laser excitation provides us with time-dependent dansyl-heme distance distributions during the two-state\nfolding process.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131010-083823832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131010-083823832", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Ford, Nicole B.; Shin, Dong Woo; et el." }, { "id": "https://authors.library.caltech.edu/records/y1hzn-hey98", "eprint_id": 39380, "eprint_status": "archive", "datestamp": "2023-08-19 19:18:30", "lastmod": "2023-10-24 16:45:17", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Pieterick-A-P", "name": { "family": "Pieterick", "given": "Adam P." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Efficient and stable photoelectrochemical energy conversion using p-type WSe2 photocathodes implications", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "We have synthesized highly cryst. p-type WSe2 and characterized its electrochem. and photoelectrochem. behavior in a variety of\naq. redox couples. Energy conversion efficiencies of > 7% with respect to the thermodn. potential for hydrogen evolution have\nbeen achieved for p-WSe2 photocathodes deposited with a mixed Ru/Pt cocatalyst under 100 mW cm^(-2) white light illumination.\nAddnl., these photocathodes exhibit good stability during photoredn. of Me viologen for at least two hours under illumination at\npH values of 2 and 10. Spectral response measurements suggest that energy conversion efficiencies are limited by short\nminority-carrier diffusion lengths, but impedance spectroscopy indicates that the p-WSe2 band-edge positions are nearly ideal for\nattaining max. photovoltages for the hydrogen evolution reaction.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130716-081436296", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-081436296", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "McKone, James R.; Pieterick, Adam P.; et el." }, { "id": "https://authors.library.caltech.edu/records/7e3pm-p6f19", "eprint_id": 39517, "eprint_status": "archive", "datestamp": "2023-08-19 19:21:10", "lastmod": "2023-10-24 16:53:48", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pribisko-M-A", "name": { "family": "Pribisko", "given": "Melanie A." } }, { "id": "Lim-Punnajit", "name": { "family": "Lim", "given": "Punnajit" }, "orcid": "0000-0002-0159-1549" }, { "id": "Termini-J", "name": { "family": "Termini", "given": "John" }, "orcid": "0000-0002-4043-7552" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Palmer-J-H", "name": { "family": "Palmer", "given": "Joshua H." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Functionalized corroles as diatherapeutic, multi-modal imaging agents", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Recent synthetic advancements have made it possible to produce substituted derivs. of meso-5,10,15-(tris)\npentafluorophenylcorrole (H_3tpfc) in reasonable yields. We present the scalable syntheses of new H_3tpfc derivs., and a few of\ntheir metal complexes, through nucleophilic arom. substitution on the pentafluorophenyl substituents. These complexes have\npotential applications both as imaging agents and chemotherapeutic drugs.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130723-085848481", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130723-085848481", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Pribisko, Melanie A.; Lim, Punnajit; et el." }, { "id": "https://authors.library.caltech.edu/records/fq48s-mp596", "eprint_id": 39460, "eprint_status": "archive", "datestamp": "2023-08-19 19:19:54", "lastmod": "2023-10-24 16:49:52", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Making oxygen: Novel catalytic transition metal oxide nanoparticles made by pulsed laser ablation in liquids", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Powering the Planet sustainably poses the greatest challenge to humankind. Harvesting solar energy by water splitting will set\nthe stage for clean fuel generation, using Earth-abundant, environmentally friendly transition metal nanomaterial catalysts.We\nuse pulsed laser ablation (PLA) in liqs. to synthesize novel nanomaterials with unique electronic and catalytic properties that are\nstable under anodic conditions, and that exhibit high oxygen-evolution efficiencies. Nanoparticle catalysts exhibit max. surface\narea and introduce addnl. benefits through the modulation of electronic properties as a result of quantum confinement.\nTransition metal oxides are the most promising catalytic materials for electrochem. oxygen evolution from water.We present a\nsystematic study of cobalt oxide and mixed metal oxide nanoparticles made by PLA in water, which we synthesized as a function\nof irradn. intensity and time, with and without additives. We characterized the nanomaterials by absorption spectroscopy, ICPMS,\nXPS, TEM, and voltammetry, and we assessed their oxygen-evolution capability.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130719-083843047", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130719-083843047", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "M\u00fcller, Astrid M.; Blakemore, James D.; et el." }, { "id": "https://authors.library.caltech.edu/records/aqtej-0hc75", "eprint_id": 39624, "eprint_status": "archive", "datestamp": "2023-08-19 19:22:04", "lastmod": "2023-10-24 17:00:27", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Marinescu-S-C", "name": { "family": "Marinescu", "given": "Smaranda C." }, "orcid": "0000-0003-2106-8971" }, { "id": "Dempsey-J-L", "name": { "family": "Dempsey", "given": "Jillian L." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Mechanistic investigations of cobalt-catalyzed hydrogen evolution", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Natural photosynthesis uses sunlight to drive the conversion of energy-poor mols. (H_2O, CO_2) to energy-rich ones (O_2, CH_2O_n).\nMany scientists are actively engaged in developing efficient artificial photosynthetic systems that split water into H_2 and O_2.\nSolar fuels prodn. involves three basic components: light absorption; charge transport; and multielectron redox catalysis. High\non the list of challenges is the discovery of mols. that efficiently catalyze the redn. of protons to H_2. We have investigated the\nmechanisms of two types of cobalt hydrogen evolution catalysts: Co^(II)-diglyoxime and Co^I-(1,1,1-tris(diphenylphosphinomethyl)\nethane) complexes. Time resolved spectroscopic measurements have provided crit. insights into the kinetics of H_2 prodn. In\nboth cases, protonation of Co^I produces a Co^(III)-H complex. Redn. of Co^(III)-H by Co^I produces a Co^(II)-H transient that reacts\nrapidly with proton donors to produce H_2.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130729-103349212", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130729-103349212", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Marinescu, Smaranda C.; Dempsey, Jillian L.; et el." }, { "id": "https://authors.library.caltech.edu/records/pctcb-x8136", "eprint_id": 39433, "eprint_status": "archive", "datestamp": "2023-08-19 19:19:33", "lastmod": "2023-10-24 16:48:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mercado-R", "name": { "family": "Mercado", "given": "Rocio" } }, { "id": "Rose-M-J", "name": { "family": "Rose", "given": "Michael J." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Mechanistic studies of fluorinated cobaloximes", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "In a previous work, a family of cobalt complexes derived from the fluorinated diphenylglyoxime ligand (\"dAr^FgH_2\") was\nsynthesized. These complexes, [Co(dAr^FgH)_2(py)_2] (1 ) and [Co(dAr^FgH-BF_2)_2(py)_2] (2 ), are variations of the extensively\nstudied diglyoxime systems [Co(dRgBF_2)_2L_2] (R = Me, phenyl), which have been shown to catalyze hydrogen evolution at low\noverpotentials. Like these catalysts, 2 minimizes energy losses by generating hydrogen at negligible thermodn. overpotentials\nin electrocatalysis expts. Through cyclic voltammetry, it was detd. that hydrogen evolution is occurring in protic solns. at the\nsecond redn. potential (-0.88 V vs. Its precursor, 1 , was also characterized and studied as a means of better understanding the\nhydrogen evolution pathway in 2 since both complexes possess a similar electronic structure. This complex exhibits a similar\ncatalytic peak at E = -0.86 V vs. Nevertheless, the two complexes differ in their electrochem. and suggest that the asym.\ncomplex 2 is a better catalyst for hydrogen evolution.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130718-080740331", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130718-080740331", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Mercado, Rocio; Rose, Michael J.; et el." }, { "id": "https://authors.library.caltech.edu/records/8ktd5-7p471", "eprint_id": 39393, "eprint_status": "archive", "datestamp": "2023-08-19 19:18:51", "lastmod": "2023-10-24 16:46:22", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Molecular proton-reduction catalysis at silicon semiconductor surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Driving catalysis at semiconductor:liq. junctions with light enables the efficient conversion and storage of solar energy in chem.\nfuels. Hydrogen evolution from water is one possible path to fuel, as there are known heterogeneous and homogeneous\ncatalysts for proton redn. Homogeneous catalysts show the greatest promise for clarifying both (1) key mechanistic aspects of\nthe hydrogen-evolution reaction at the surface and (2) energetic considerations of the semiconductor band structure. Along this\nline, we are studying a family of rhodium complexes as model catalysts for hydrogen evolution at semiconductor:liq. junctions.\nBoth diffusional and silicon surface-attached systems have been developed, and will be compared. This approach has yielded\nnew information concerning the ambiguities of homogeneous vs. Heterogeneous catalysis, as well as the possible catalytic\nmechanism(s) of the surface-attached species.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130716-130435999", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-130435999", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Blakemore, James D.; Lattimer, Judith R.; et el." }, { "id": "https://authors.library.caltech.edu/records/kq7y8-34228", "eprint_id": 37850, "eprint_status": "archive", "datestamp": "2023-08-19 19:10:42", "lastmod": "2023-10-23 19:03:15", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "NSF Center for Chemical Innovation Solar Fuels program", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "The NSF Center for Chem. Innovation in Solar Fuels (CCI Solar) focuses on one of the holy\ngrails of 21st century chem. - the efficient and economical conversion of solar energy into\nstored chem. fuel. CCI Solar activities directly impact thousands of students, postdoctoral\nscholars, working scientists, and members of the public at large. Our outreach program\ndelivers Juice-from-Juice solar science activity kits to elementary, middle, and high school\nstudents. Solar Energy Activity Lab kits introduce high school and undergraduate students\nto research involving a combinatorial search for new solar materials. CCI Solar graduate\nstudents and postdoctoral scholars acquire invaluable experience by serving as mentors in\nthese outreach programs. CCI Solar researchers are delivering the message of clean\nrenewable solar fuels in television, radio, and online programs, as well as in public\nlectures, scientific research conferences, and consultations with local, state, and federal\ngovernment officials. The technol., environmental, economic, and social benefits of\nrenewable solar fuels cannot be overstated, as every human being on Earth would be\nimpacted by the development of sustainable energy resources.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130410-101631371", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130410-101631371", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Gray, Harry B." }, { "id": "https://authors.library.caltech.edu/records/p8g3q-xpg84", "eprint_id": 39458, "eprint_status": "archive", "datestamp": "2023-08-19 19:19:40", "lastmod": "2023-10-24 16:49:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jackson-M-N", "name": { "family": "Jackson", "given": "Megan N." } }, { "id": "Ener-M-E", "name": { "family": "Ener", "given": "Maraia E." } }, { "id": "Warren-J-J", "name": { "family": "Warren", "given": "Jeffrey J." }, "orcid": "0000-0002-1747-3029" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Pt(pop-BF2) as a photosensitizer in photocatalytic carbon-chlorine bond formation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Palladium complexes perform regioselective C-H functionalizations, which are essential for many syntheses. We are interested in\nhalogenation of C-H bonds using [(benzo[h]quinoline)PdII(\u03bc-OAc)]2 catalysts. Bulk electrolysis expts. show that we can\nchlorinate C-H bonds using chloride and Pd catalysts, eliminating the need for harsh chlorinating agents. To improve the speed\nand energetic cost of C-H transformations we are exploring reactions with photooxidants. Electronically excited fluoroborated\ntetrakis(\u03bc-pyrophosphito)diplatinate(II) (Pt(pop-BF2)) undergoes facile electron transfer reactions. Electrochem. (E\u00b0(PtII-PtII/PtIPtII)\n= 1.3 V vs. SCE in MeCN) and fluorescence data were used to calc. E\u00b0(*PtII-PtII/PtII-PtI) = 1.4 V vs. SCE, suggesting that\nelectronically excited Pt(pop-BF2) can oxidize Pd catalysts. Absorbance spectra of the transiently reduced Pt complexes were\nrecorded. Time-resolved laser expts. in the presence of Pd catalyst suggest that *Pt(pop-BF2) generates catalytically active Pd\nintermediates, making it a viable sensitizer for photocatalyic C-H functionalizations.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130719-081932359", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130719-081932359", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Jackson, Megan N.; Ener, Maraia E.; et el." }, { "id": "https://authors.library.caltech.edu/records/t2h8p-5qa20", "eprint_id": 39372, "eprint_status": "archive", "datestamp": "2023-08-19 19:18:16", "lastmod": "2023-10-24 16:44:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Darnton-T-V", "name": { "family": "Darnton", "given": "Tania V." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Pulsed laser ablation synthesis of nanostructured proton reduction catalysts", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Emerging global energy demands and the overarching need to reduce fossil fuel consumption have strongly motivated the study\nof artificial photosynthesis in the past decade. One great challenge is to develop systems that efficiently catalyze the redn. of H+\nto H_2. We are investigating the prepn. of catalytic nanoparticles using pulsed laser ablation of solid targets immersed in liqs.\n(PLAL). PLAL generates picoliter reaction vols. of a liq.-confined plasma characterized by extremes of temp., pressure, and atom\nd., permitting exploration of extreme regions of materials phase diagrams. Initial efforts have been directed toward MoS_2, a\nknown proton redn. catalyst. PLAL expts. with a powd. MoS_2 target have produced a nanoparticulate material. Full\ncharacterization of this material, including evaluation of its electrocatalytic H_2 evolution performance, will be presented. Effects\nof laser pulse energy, ablation time, and liq. medium on nanoparticle size, compn., morphol., and proton redn. activity will also\nbe examd.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130715-145633172", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130715-145633172", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Darnton, Tania V.; Winkler, Jay R.; et el." }, { "id": "https://authors.library.caltech.edu/records/h2zt9-yq387", "eprint_id": 39501, "eprint_status": "archive", "datestamp": "2023-08-19 19:20:43", "lastmod": "2023-10-24 16:52:10", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Marinescu-S-C", "name": { "family": "Marinescu", "given": "Smaranda" }, "orcid": "0000-0003-2106-8971" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay" }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry" }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar fuels", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Our NSF funded CCI Solar Fuels Program involves many experimentalists and theorists in an interdisciplinary effort with the goal\nof developing light absorbers and catalysts that could be incorporated in devices to split water to hydrogen and oxygen. Our\nemphasis is on heterogeneous and homogeneous catalysts made from earth-abundant elements that could be part of scalable\nsolar fuel devices. While homogeneous catalysts typically degrade faster than their heterogeneous counterparts, mol. systems\nare much easier to study mechanistically. In recent work on hydrogen evolution from protic solns. catalyzed by a tripodal\nphosphine cobalt complex, we have shown that the dominant reaction channel involves a Co(II)-hydride as the reactive\nintermediate. The lessons we have learned from such mechanistic investigations are guiding the design and construction of very\nactive catalysts both for water redn. and oxidn.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130722-132336387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130722-132336387", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Marinescu, Smaranda; Winkler, Jay; et el." }, { "id": "https://authors.library.caltech.edu/records/76v1f-8gg40", "eprint_id": 42175, "eprint_status": "archive", "datestamp": "2023-08-19 19:25:24", "lastmod": "2023-10-25 15:43:22", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Trinh-C", "name": { "family": "Trinh", "given": "Cong" } }, { "id": "Kirlikovali-K", "name": { "family": "Kirlikovali", "given": "Kent" } }, { "id": "Das-S", "name": { "family": "Das", "given": "Saptaparna" } }, { "id": "Bradforth-S-E", "name": { "family": "Bradforth", "given": "Stephen E." } }, { "id": "Ener-M-E", "name": { "family": "Ener", "given": "Maraia E." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Djurovich-P-I", "name": { "family": "Djurovich", "given": "Peter I." } }, { "id": "Thompson-M-E", "name": { "family": "Thompson", "given": "Mark E." }, "orcid": "0000-0002-7764-4096" } ] }, "title": "Symmetry breaking charge transfer processes of zinc dipyrrin complexes", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Photoinduced charge transfer (CT) via symmetry breaking (SB) processes plays a crucial role in\nphotosynthetic reaction center of biol. systems. In such systems, which contain two or more identical and sym.\nchromophores, CT process from one to another chromophore occurs upon photo-excitation, thus breaking the\nsymmetry. It is of great interest to apply SBCT processes in org. photovoltaics (OPV) and related systems.\nFor application to OPVs, it is desirable for compds. that undergo SB processes to have absorption in the visible\nspectrum. The most well-documented compds. for SB phenomenon, such as bianthryl derivs., do not absorb\nvisible light. Herein we present study on Zinc Dipyrrin complexes, which contain two identical dipyrrin\nligands and absorb strongly at 450-550 nm. These compds. undergo efficient SBCT processes in polar\nsolvents; the photoinduced CT state from the singlet excited state occurs in 4-7 ps, and then recombines back to\nthe triplet state in 1-4 ns.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131101-085854371", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131101-085854371", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Trinh, Cong; Kirlikovali, Kent; et el." }, { "id": "https://authors.library.caltech.edu/records/zfwrp-qws85", "eprint_id": 33247, "eprint_status": "archive", "datestamp": "2023-08-19 04:37:02", "lastmod": "2023-10-18 18:55:01", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yokoyama-Keiko", "name": { "family": "Yokoyama", "given": "K." } }, { "id": "Nakamura-N", "name": { "family": "Nakamura", "given": "N." } }, { "id": "Ohno-Hiroyuki", "name": { "family": "Ohno", "given": "H." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "J. R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Richards-J-H", "name": { "family": "Richards", "given": "J. H." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "H. B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Electron tunneling through mutant azurins on mixed SAM gold electrodes", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2012 American Chemical Society.", "abstract": "We are investigating interfacial electron transfer rates of P. aeruginosa azurin and its mutants using electrochem. at 1:1\nCH3(CH2)nSH:HO(CH2)nSH mixed-SAM gold electrodes. We have examd. interfacial electron transfer rates of mutant\nazurins in which asparagine-47 was replaced by alanine, aspartic acid, lysine, arginine, leucine, threonine, serine, and\nglutamine. The N47D mutant on a mixed SAM exhibited a well-defined electrochem. response; N47T and N47S gave a\nweak signal; but the other 5 mutants showed no response. It is likely that the N47 side-chain carbonyl interacts with the\nmixed SAM surface, providing a very favorable electron tunneling pathway to the copper via an N47-C112 hydrogen\nbond. We also have examd. interfacial electron transfer rates of M121X mutant azurins. The ET rates for M121E are 2\norders of magnitude smaller; those for M121Q are almost 1 order of magnitude smaller; and those for the M121L protein\nare similar to those of wild-type azurin at pH 7. In addn., we have found that type zero azurins have higher ET rates than\nthose of type 2 proteins (rates for C112D are 3 orders of magnitude smaller; those for type zero C112D/M121X (X=L and\nI) are 2 orders of magnitude smaller than wild-type at pH 7).", "date": "2010-12", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20120816-072045664", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120816-072045664", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2010", "author_list": "Yokoyama, K.; Nakamura, N.; et el." }, { "id": "https://authors.library.caltech.edu/records/5qj1s-cty37", "eprint_id": 46142, "eprint_status": "archive", "datestamp": "2023-08-19 19:46:11", "lastmod": "2023-10-26 18:43:00", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gray-H-B", "name": { "family": "Gray", "given": "H. B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Dempsey-J-L", "name": { "family": "Dempsey", "given": "J. L." } }, { "id": "Shih-Crystal", "name": { "family": "Shih", "given": "C." } }, { "id": "Lancaster-K-M", "name": { "family": "Lancaster", "given": "K. M." }, "orcid": "0000-0001-7296-128X" }, { "id": "Wilson-C", "name": { "family": "Wilson", "given": "C." } }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "J. R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Sensitizer-modified proteins for solar-driven water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society.", "abstract": "Aerobic respiration and photosynthesis work in concert: Dioxygen liberated by photosynthetic organisms sustains life in aerobic\nmicrobes and animals; and, in turn, the products of aerobic respiratory metab., carbon dioxide and water, nourish\nphotosynthetic organisms. Electron flow through proteins and protein assemblies in the photosynthetic and respiratory\nmachinery commonly occurs between metal centers or other redox cofactors that are sepd. by relatively large mol. distances,\noften in the 10 to 20 angstrom range. Both theorists and experimentalists have worked long and hard in attempts to understand\nthe underlying physics and chem. of these electron transport processes. Lessons learned about the control of electron tunneling\nand hopping through org. and biol. mols. are now being used to design sensitizer-modified protein machines incorporating\ncatalysts that can generate hydrogen fuel from sunlight and water.", "date": "2007-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140609-091548403", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140609-091548403", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2007", "author_list": "Gray, H. B.; Dempsey, J. L.; et el." } ]