The feasibility of artificial photosynthesis depends on the development of catalysts that can efficiently use water as both an electron source and a proton source.1,2 Hydrocarbon oxidation/activation under mild conditions is an important goal for more efficient use of petroleum feedstocks. In either, major challenges arise from the multiple electron/multiple proton changes for typical half reactions- 2H2O → O2 + 4e- + 4H+; CH4 + H2O → CH3OH + 2e- + 2H+- and kinetic demands arising from single electron activation of these multi-electron transfer steps.3 One approach to both is to utilize PCET (proton-coupled electron transfer) oxidative activation of precursor aqua complexes to high oxidation state oxo complexes, e.g., RuII(tpy)(bpy)(OH2)2+ -e,-H+→ RuIII(tpy)(bpy)(OH)2+ -e,-H+→ RuIV(tpy)(bpy)(O)2+, where tpy is 2,2’:6’,2”-terpyridine and bpy is 2,2’-bipyridine.4 Loss of both electrons and protons avoids charge build up and high energy intermediates, enabling the accumulation of multiple redox equivalents at single sites or clusters. We report on the surface coordination of the reactive complex cis-[Ru(4,4’-(H2O3P)2-bpy)2(OH2)2]2+ by coordination to metal oxide electrode surfaces. When surface-bound by phosphonate-surface binding, the complex undergoes multiple electron transfer on the surface from Ru(II) to Ru(VI). It is also an electrocatalyst based in surface Ru(VI/IV)) and Ru(IV/II) couples for organic and inorganic oxidations. On the surface, the complex is a precursor to the preparation of more complex assemblies based on ligand substitution. Electrocatalytic experiments and preliminary investigations toward the preparation of more complex surface assemblies will be discussed.

Surface synthesis of molecular assemblies: Application in energy conversion

254th National Meeting (2017)

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