Light-driven Hydrogen Evolution from Water by a Tripodal Silane Based Co6IIL81 Octahedral Cage

The octahedral cage assembly [(Co6L8CI6)-L-II-C-1(H2O)(6)]C1=l(6) has been synthesized in a single-step reaction by using a polypyridyl-functionalized tripodal silane ligand. The electrochemical behavior of the cage in water exhibits the pH dependence of potential as well as catalytic current indicating the possible involvement of proton -coupled electron transfer in H-2 evolution. Electrocatalytic hydrogen evolution from an aqueous buffered solution gave a turnover frequency of 16 h(-1). Further, this cage assembly has been explored as a photocatalyst (blue light irradiation lambda 469 nm) for the evolution of H-2 from water in the presence of Ru(bpy)(3)(2+) as a photosensitizer and ascorbic acid as a sacrificial electron donor. This catalytic reaction is found to be pseudo first order with a turnover frequency of 20.50 h(-1).