New Ir(III) 4,4′-dicyano-2,2′-bipyridine photosensitizers for solar fuel generation

Abstract

Two new photosensitizer complexes were synthesized featuring 4,4′-dicyano-2,2′-bipyridine binding moieties to better facilitate water and zinc reduction. DFT calculations, electrochemical characterization, and photophysical studies revealed the presence of a narrower HOMO–LUMO gap than 2,2′-bipyridine analogs, and shorter excited-state lifetimes. These properties were reflected in the water reduction studies; the newly-synthesized compounds surpassed current art when using colloidal catalysts, but were less efficient when using molecular catalysts. The complexes were also shown to facilitate Zn(II) photoreduction.