Author
James P. Collman
Other affiliations: Northwestern University, Centre national de la recherche scientifique, Carnegie Mellon University
Bio: James P. Collman is an academic researcher from Stanford University. The author has contributed to research in topics: Porphyrin & Cytochrome c oxidase. The author has an hindex of 74, co-authored 393 publications receiving 21330 citations. Previous affiliations of James P. Collman include Northwestern University & Centre national de la recherche scientifique.
Topics: Porphyrin, Cytochrome c oxidase, Catalysis, Ruthenium, Heme
Papers published on a yearly basis
Papers
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01 Jan 1980
TL;DR: A perspective survey of organotransition metal complexes according to ligand substitution processes can be found in this paper, with a focus on transition metal complexes with metal carbon-bonded ligands.
Abstract: A perspective Bonding Survey of organotransition metal complexes according to ligand Ligand substitution processes Oxidative-addition and reductive elimination Intramolecular insertion reactions Nucleophilic attack on ligands coordinated to transition metals Electrophilic attacks on coordinated ligands Metallacycles Homogeneous catalytic hydrogenation, hydrosilation, and hydrocyanation Catalytic polymerization of olefins and acetylenes Catalytic reactions involving carbon monoxide Synthetic applications of transition metal hydrides Synthetic applications of transition metal complexes containing metal carbon bonds Synthetic applications of transition metal carbonyl compounds Synthetic application of transition metal carbenes and metallacycles Synthetic applications of transition metal alkene, diene, and duenyl complexes Synthetic applications of transition metal alkyne complexes Synthetic applications of -allyl transition metal complexes Synthetic applications of transition metal arene complexes.
1,795 citations
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711 citations
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TL;DR: The majority of modern organisms, including many prokaryotes, are aerobes; that is, they use molecular oxygen as the terminal electron acceptor for energy generation, and the four-electron, four-proton reduction of O2 to H2O (reaction 1) dominates.
Abstract: The majority of modern organisms, including many prokaryotes, are aerobes;1 that is, they use molecular oxygen as the terminal electron acceptor for energy generation. Although nearly every redox gradient in nature appears to be utilized by one organism or another,2-4 aerobic metabolism predominates, in large part due to the highly exergonic nature of the four-electron, four-proton (4e/4H+) reduction of O2 to H2O (reaction 1). A multicellular aerobe requires an
599 citations
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TL;DR: In this paper, a series of dimeric metalloporphyrin molecules has been synthesized in which the two porphrin rings are constrained to lie parallel to one another by two amide bridges of varying length that link the rings together.
Abstract: A series of dimeric metalloporphyrin molecules has been synthesized in which the two porphyrin rings are constrained to lie parallel to one another by two amide bridges of varying length that link the rings together. These cofacial metalloporphyrins have been applied to the surface of graphite electrodes and tested for catalytic activity toward the electroreduction of dioxygen to water in aqueous acidic electrolytes. All molecules tested exhibited some catalytic activity, but hydrogen peroxide rather than water was the chief reduction product. However, the dicobalt cofacial porphyrin linked by four-atom bridges produced a catalyzed reduction almost exclusively to water and at exceptionally positive potentials. Rotating ring-disk voltametric measurements were employed to diagnose the electrode reaction pathway and a possible mechanism for the observed catalysis is suggested. The results seem to demonstrate the participation of two metal centers in controlling the course of a multiple-electron process.
558 citations
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TL;DR: The applicability of Sharpless “click” chemistry, specifically Huisgen 1,3-dipolar cycloadditions, as a general methodology for functionalizing surfaces coated with self-assembled monolayers is demonstrated.
Abstract: We demonstrate the applicability of Sharpless “click” chemistry, specifically Huisgen 1,3-dipolar cycloadditions, as a general methodology for functionalizing surfaces coated with self-assembled monolayers. Ferrocene immobilization was used as our model, and the resulting monolayers were analyzed using traditional surface analytical techniques. Our preliminary results indicate that this reaction proceeds to completion at room temperature in aqueous solvent. The triazole group is a thermally and hydrolytically stable, conjugated linkage. The reactants, acetylenes and azides, are independently stable; they do not react with common organic reagents or with themselves. Thus the potential for this reaction to immobilize a wide range of functionally complex substances on metal surfaces is significant. To our knowledge this is the first report of the use of “click” chemistry to modify a well-defined electrode surface.
476 citations
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7,711 citations
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TL;DR: It is reported that vertically aligned nitrogen-containing carbon nanotubes (VA-NCNTs) can act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction in alkaline fuel cells.
Abstract: The large-scale practical application of fuel cells will be difficult to realize if the expensive platinum-based electrocatalysts for oxygen reduction reactions (ORRs) cannot be replaced by other efficient, low-cost, and stable electrodes. Here, we report that vertically aligned nitrogen-containing carbon nanotubes (VA-NCNTs) can act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction in alkaline fuel cells. In air-saturated 0.1 molar potassium hydroxide, we observed a steady-state output potential of –80 millivolts and a current density of 4.1 milliamps per square centimeter at –0.22 volts, compared with –85 millivolts and 1.1 milliamps per square centimeter at –0.20 volts for a platinum-carbon electrode. The incorporation of electron-accepting nitrogen atoms in the conjugated nanotube carbon plane appears to impart a relatively high positive charge density on adjacent carbon atoms. This effect, coupled with aligning the NCNTs, provides a four-electron pathway for the ORR on VA-NCNTs with a superb performance.
6,370 citations
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TL;DR: The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier.
Abstract: The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.
3,855 citations
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TL;DR: The resultant N-graphene was demonstrated to act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction via a four-electron pathway in alkaline fuel cells.
Abstract: Nitrogen-doped graphene (N-graphene) was synthesized by chemical vapor deposition of methane in the presence of ammonia. The resultant N-graphene was demonstrated to act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction via a four-electron pathway in alkaline fuel cells. To the best of our knowledge, this is the first report on the use of graphene and its derivatives as metal-free catalysts for oxygen reduction. The important role of N-doping to oxygen reduction reaction (ORR) can be applied to various carbon materials for the development of other metal-free efficient ORR catalysts for fuel cell applications, even new catalytic materials for applications beyond fuel cells.
3,604 citations
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TL;DR: O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH..
Abstract: O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH.. SODs inhibit such HO. production by scavengingO2-, but Cu, ZnSODs, by virtue of a nonspecific peroxidase activity, may peroxidize spin trapping agents and thus give the appearance of catalyzing OH. production from H2O2. There is a glycosylated, tetrameric Cu, ZnSOD in the extracellular space that binds to acidic glycosamino-glycans. It minimizes the reaction of O2- with NO. E. coli, and other gram negative microorganisms, contain a periplasmic Cu, ZnSOD that may serve to protect against extracellular O2-. Mn(III) complexes of multidentate macrocyclic nitrogenous ligands catalyze the dismutation of O2- and are being explored as potential pharmaceutical agents. SOD-null mutants have been prepared to reveal the biological effects of O2-. SodA, sodB E. coli exhibit dioxygen-dependent auxotrophies and enhanced mutagenesis, reflecting O2(-)-sensitive biosynthetic pathways and DNA damage. Yeast, lacking either Cu, ZnSOD or MnSOD, are oxygen intolerant, and the double mutant was hypermutable and defective in sporulation and exhibited requirements for methionine and lysine. A Cu, ZnSOD-null Drosophila exhibited a shortened lifespan.
3,298 citations