Water oxidation to oxygen is one of the half reactions in natural photosynthesis as well as in many schemes for solar fuels production. For the latter, one of the main challenges is the development of efficient and robust water oxidation catalysts. In this presentation, we describe water oxidation by ruthenium complexes bearing phosphonate-derivatized polypyridyl ligands. This study involves the synthesis and characterization of ligands and complexes, including the X-ray structures of several complexes. It also includes pH-dependent electrochemistry in solution and with the catalysts anchored to metal-oxide electrodes in a true device configuration. The experimental results are complemented by a detailed analysis using DFT calculations. In these complexes, the phosphonate groups provide redox potential leveling through charge compensation and sigma donation allowing easy access to high oxidation states. They also act as proton shuttles moving protons in and out of the catalytic site thus reducing activation barriers.

Water oxidation by ruthenium complexes incorporating phosphonate-derivatized polypyridyl ligands

249th National Meeting (2015)

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