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

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.

Graphical abstractTwo new Ir(III) photosensitizers featuring 4,4′-dicyano-2,2′-bipyridine were synthesized, characterized, and evaluated for water and Zn(II) photoredution. The complexes were proficient water reduction photosensitizers with colloidal catalysts due to the bridging nature of the cyano groups; this was not observed with molecular catalysts. The complexes were shown to promote Zn(II) photoreduction.Figure optionsDownload full-size imageDownload as PowerPoint slide