Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis

Grills, David C.; Polyansky, Dmitry E.; Fujita, Etsuko

doi:10.1002/cssc.201701559

Cited by 30 publications

(34 citation statements)

References 73 publications

(94 reference statements)

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“…Complementary mechanistic information can be obtained by characterization of WOC intermediates, by means of transient spectroscopy combined to flash photolysis experiments. It is worth recalling that the fast generation and characterization of reactive intermediates can be performed also by pulse radiolysis, a field that has been recently reviewed by Fujita et al…”

Section: Photogenerated Woc Intermediatesmentioning

confidence: 99%

Mechanistic Insights into Light‐Activated Catalysis for Water Oxidation

et al. 2019

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The development of catalysts for water oxidation to oxygen has been the subject of intense investigation in the last decade. In parallel to the search for high catalytic performance, many works have focused on the mechanistic analysis of the process. In this perspective, the oxidation of water through light‐assisted cycles composed of an electron acceptor (EA), a photosensitizer (PS), and a water oxidation catalyst (WOC) can provide insightful and complementary information with respect to the use of chemical oxidants or to electrochemical techniques. In this minireview, we discuss the mechanistic aspects of the EA/PS/WOC photoactivated cycles, and in particular: (i) the general elementary steps; (ii) the required features and the nature of the PS employed; (iii) the electron transfer processes and kinetics from the WOC to PS+ (hole scavenging); (iv) the detrimental quenching of the PS by the WOC and the alternative mechanistic routes; (v) the identification of WOC intermediates and, finally, (vi) the transposition of the above processes into a dye‐sensitized photoanode embedding a WOC.

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Section: Photogenerated Woc Intermediatesmentioning

confidence: 99%

Mechanistic Insights into Light‐Activated Catalysis for Water Oxidation

et al. 2019

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“…Reduced metal complexes also attract significant attention in the area of molecular electrocatalysis [ 4 ], as several reduced intermediates are typically involved in multielectron redox cycles that generate fuels like H 2 via H + and e − coupling [ 5 , 6 ]. In many of these cycles, however, the key metal complexes reduced by one or more e − equivalents are not isolated or detected—instead, their involvement is inferred from the observed reactivity [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, Rh I is very quickly generated following formation of Rh II , because the E (Rh II /Rh I ) is more positive than E (Rh III /Rh II ). These two-electron events obscure the routine measurement of the individual one-electron reduction events involved in this chemistry [ 7 , 10 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…The energy conversion efficiency of these [Cp*Rh] catalysts is closely tied to the potentials of the individual reduction events [ 7 , 17 , 18 ], but only a limited level of control of these parameters has been demonstrated to date. Moreover, the use of redox-active bpy ligands (and other diimines) in these complexes has attracted significant attention [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

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Single-Electron Redox Chemistry on the [Cp*Rh] Platform Enabled by a Nitrated Bipyridyl Ligand

Moore¹,

Henke²,

Lionetti³

et al. 2018

Molecules

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[Cp*Rh] complexes (Cp* = pentamethylcyclopentadienyl) are attracting renewed interest in coordination chemistry and catalysis, but these useful compounds often undergo net two-electron redox cycling that precludes observation of individual one-electron reduction events. Here, we show that a [Cp*Rh] complex bearing the 4,4′-dinitro-2,2′-bipyridyl ligand (dnbpy) (3) can access a distinctive manifold of five oxidation states in organic electrolytes, contrasting with prior work that found no accessible reductions in aqueous electrolyte. These states are readily generated from a newly isolated and fully characterized rhodium(III) precursor complex 3, formulated as [Cp*Rh(dnbpy)Cl]PF6. Single-crystal X-ray diffraction (XRD) data, previously unavailable for the dnbpy ligand bound to the [Cp*Rh] platform, confirm the presence of both [η5-Cp*] and [κ2-dnbpy]. Four individual one-electron reductions of 3 are observed, contrasting sharply with the single two-electron reductions of other [Cp*Rh] complexes. Chemical preparation and the study of the singly reduced species with electronic absorption and electron paramagnetic resonance spectroscopies indicate that the first reduction is predominantly centered on the dnbpy ligand. Comparative cyclic voltammetry studies with [NBu4][PF6] and [NBu4][Cl] as supporting electrolytes indicate that the chloride ligand can be lost from 3 by ligand exchange upon reduction. Spectroelectrochemical studies with ultraviolet (UV)-visible detection reveal isosbestic behavior, confirming the clean interconversion of the reduced forms of 3 inferred from the voltammetry with [NBu4][PF6] as supporting electrolyte. Electrochemical reduction in the presence of triethylammonium results in an irreversible response, but does not give rise to catalytic H2 evolution, contrasting with the reactivity patterns observed in [Cp*Rh] complexes bearing bipyridyl ligands with less electron-withdrawing substituents.

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“… 122 The binding of CO 2 to Ni( i ) complexes has been extensively studied by pulse radiolysis measurements to demonstrate that the formation of the Ni( i )–CO 2 adduct is in equilibrium between the Ni( i ) complex and free CO 2 . 123 , 124 …”

Section: Electrocatalytic Reduction Of Co 2 To Co mentioning

confidence: 99%