Base-enhanced catalytic water oxidation by a carboxylate-bipyridine Ru(II) complex

Na Song; Javier J Concepcion; Robert A Binstead; Jennifer A Rudd; Aaron K Vannucci; Christopher J Dares; Michael K Coggins; Thomas J Meyer

doi:10.1073/pnas.1500245112

Base-enhanced catalytic water oxidation by a carboxylate-bipyridine Ru(II) complex

Proc Natl Acad Sci U S A. 2015 Apr 21;112(16):4935-40. doi: 10.1073/pnas.1500245112. Epub 2015 Apr 6.

Authors

Na Song¹, Javier J Concepcion¹, Robert A Binstead¹, Jennifer A Rudd¹, Aaron K Vannucci¹, Christopher J Dares¹, Michael K Coggins¹, Thomas J Meyer²

Affiliations

¹ Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290.
² Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290 tjmeyer@unc.edu.

Abstract

In aqueous solution above pH 2.4 with 4% (vol/vol) CH3CN, the complex [Ru(II)(bda)(isoq)2] (bda is 2,2'-bipyridine-6,6'-dicarboxylate; isoq is isoquinoline) exists as the open-arm chelate, [Ru(II)(CO2-bpy-CO2(-))(isoq)2(NCCH3)], as shown by (1)H and (13)C-NMR, X-ray crystallography, and pH titrations. Rates of water oxidation with the open-arm chelate are remarkably enhanced by added proton acceptor bases, as measured by cyclic voltammetry (CV). In 1.0 M PO4(3-), the calculated half-time for water oxidation is ∼7 μs. The key to the rate accelerations with added bases is direct involvement of the buffer base in either atom-proton transfer (APT) or concerted electron-proton transfer (EPT) pathways.

Keywords: Ru polypyridyl complexes; electrocatalysis; solar energy; water oxidation catalysis; water splitting.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.