Light‐Driven Activation of the [H₂O(terpy)Mn^III‐μ‐(O₂)‐Mn^IV(terpy)OH₂] Unit in a Chromophore–Catalyst Complex

Abstract

The Living Daylight: Ruthenium‐based chromophores are employed as building blocks for a photo‐active complex bearing a known water‐oxidation catalytic system [(Terpy)2(MnIII‐μ‐(O2)‐MnIV)]. Its activation by visible light has been studied by EPR spectroscopy.

Light-driven water oxidation for solar fuels

“…Several chromophore-catalyst dyads have been assembled by covalent modification of the ligand environment of previously reported manganese- or ruthenium-based water-oxidation catalysts. Aukauloo and coworkers applied this strategy by modifying the terpyridine ligands of the previously reported [Mn III/IV 2 (tpy) 2 (μ-O) 2 (OH 2 )] 3+ dimer and incorporating a ruthenium-polypyridyl dye through a 1,10-phenanthroline-4,5-dione linkage to the ruthenium center, shown in Figure 16 [172, 173]. The modified terpyridine ligand was used to assemble a mixed-valence manganese dimer similar to that used for water oxidation with chemical oxidants, and one-electron transfer to form the Mn IV/IV complex was observed.…”

“…There are several examples in the literature of attempts to interface the previously reported [Mn III/IV 2 (tpy) 2 (μ-O) 2 (OH 2 )] 3+ dimer to chromophores for light-driven water oxidation [66, 73, 172, 173]. In each case, the one-electron oxidation from Mn III /Mn IV to Mn IV /Mn IV may be observed by EPR, but no further oxidation or production of oxygen has been reported.…”

“…Mn III/IV dimer linked to a ruthenium chromophore. This complex is observed to undergo reversible one-electron oxidation with visible light illumination [172]. …”

Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges

“…The oxidized photosensitizer subsequently abstracts an electron from the attached Mn complex. [87][88][89][90][91][92] Of the examined Ru-Mn assemblies, assembly 16 ( Fig. 8) displayed promising properties as it was able to undergo three consecutive electron transfers, which converted the initial Mn II,II 2 core to Mn III,IV 2 .…”

Visible‐Light‐Driven Generation of High‐Valent Oxo‐Bridged Dinuclear and Tetranuclear Manganese Terpyridine Entities Linked to Photoactive Ruthenium Units of Relevance to Photosystem II

“…Nevertheless, difficulties in obtaining pure compounds have prevented clear characterisation and evaluation of their photoinduced redox activities. Very recently, Herrero and coworkers reported the synthesis of two similar compounds (Scheme , c and d) 73. In the presence of [Co(NH 3 ) 5 Cl] 2+ as an irreversible electron donor, these compounds undergo a photoinduced oxidation of the manganese centre, which gives rise to EPR‐silent species that have not been identified.…”