Cobalt(III) Schiff base complexes (Co(III)-sb), developed by our group, inhibit metal-dependent pathways by irreversibly binding to histidine residues of target proteins and displacing endogenous metal ions. Currently, this process is limited by a dissociative mechanism of the Co(III)-sb axial ligands. Based on the success of this approach we are developing a light-activation mechanism that will redox-initiate the inhibition process of Co(III)-sb derivatives. Specifically, this system incorporates a bimetallic complex that utilizes the excited-state quenching ability of Ru(II) polypyridine complexes. This photo-redox active Co(III)-sb is designed to undergo single electron transfer from Ru(II) to Co(III), upon excitation of a Ru(bpy)3 moiety (450 nm) (i.). Reduction of Co(III)-sb to Co(II)-sb causes dissociation of the axial ligands (ii.). The redox potentials of Co(II)-sb and Ru(III)(bpy)3 favor the back electron transfer (iii.); we propose that this action generates the reactive Co(III)-sb species, that subsequently coordinates to the imidazole ring of histidine residues in target proteins.?

Ruthenium(II) bipyridyl complexes for activation of cobalt(III) Schiff base protein inhibitors through photoinduced electron transfer

247th National Meeting (2014)

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