A pentanuclear iron catalyst designed for water oxidation.

Although the oxidation of water is efficiently catalysed by the oxygen-evolving complex in photosystem II (refs 1 and 2), it remains one of the main bottlenecks when aiming for synthetic chemical fuel production powered by sunlight or electricity. Consequently, the development of active and stable water oxidation catalysts is crucial, with heterogeneous systems considered more suitable for practical use and their homogeneous counterparts more suitable for targeted, molecular-level design guided by mechanistic understanding. Research into the mechanism of water oxidation has resulted in a range of synthetic molecular catalysts, yet there remains much interest in systems that use abundant, inexpensive and environmentally benign metals such as iron (the most abundant transition metal in the Earth's crust and found in natural and synthetic oxidation catalysts).

Regulation of a cerium(IV)-driven O₂ evolution reaction using composites of liposome and lipophilic ruthenium complexes.

A composite containing a liposome and a lipophilic ruthenium complex was synthesized to regulate an O2 evolution reaction using cerium(IV) ammonium nitrate as an oxidizing reagent. We found that the surrounding environment of the reaction centre is an important factor for controlling the O2 evolution catalytic reaction. We successfully regulated the reaction activity using the linker length of the lipophilic ligand and using the head groups of the phospholipid component.

A mononuclear ruthenium complex showing multiple proton-coupled electron transfer toward multi-electron transfer reactions.

Two new ruthenium(II) complexes bearing dissociable protons, [Ru(trpy)(H(2)bim)Cl]PF(6) (1) and [Ru(trpy)(H(2)bim)(OH(2))](PF(6))(2) (2) (H(2)bim = 2,2'-biimidazole and trpy = 2,2':6',2''-terpyridine), were synthesized and characterized, where the H(2)bim and M-OH(2) moieties are expected to serve as proton-dissociation sites. Single crystal X-ray diffraction analyses revealed that the H(2)bim and M-OH(2) moieties act as proton donors in intermolecular hydrogen bonds. Two pK(a) values of 2 (pK(a1) = 9.