Enhancement of Solar Fuel Production Schemes by Using a Ru,Rh,Ru Supramolecular Photocatalyst Containing Hydroxide Labile Ligands

Polyazine-bridged (RuRhRuII)-Rh-II-Ru-III complexes with two halide ligands, Cl- or Br-, bound to the catalytically active Rh center are efficient single-component photocatalysts for H2O reduction to H-2 fuel, with the coordination environment on Rh impacting photocatalysis. Herein reported is a new, halide-free (RuRhRuII)-Rh-II-Ru-III photocatalyst with OH- ligands bound to Rh, further enhancing the photocatalytic reactivity of the structural motif. H-2 production experiments using the photocatalyst bearing OH- ligands at Rh relative to the analogues bearing halides at Rh in solvents of varying polarity (DMF, CH3CN, and H2O) suggest that ion pairing with halides deactivates photocatalyst function, representing an exciting phenomenon to exploit in the development of catalysts for solar H-2 production schemes.