We recently synthesized and fully characterized a photoluminescent zirconium complex and reported the first example of using amolecular zirconium compound as the photosensitizer in photocatalytic reactions. The complex Zr(MePDPPh)2 (MePDPPh = 2,6-bis(5-methyl-3-phenyl-1H-pyrrol-2-yl)pyridine) shows intense ligand-to-metal charge-transfer (LMCT) bands in the visible region and undergoes multiple reversible redox events under highly reducing conditions. Based on the electrochemical properties of the ground state and the emission profile, the excited state potential for the redox-couple Zr(MePDPPh)2*/[Zr(MePDPPh)2]1− can be estimated as −0.07 V vs Fc+/0. RBIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-7-R-benzo-[d]imidazole) derivatives were identified as viable quenchers for the excited state. This Zr/BIH system can be employed in photocatalytic debromination reactions, olefin reduction and benzyl coupling reactions. In these reactions, earth abundant zirconium serves as a low-cost replacement for the precious metal photosensitizer Ru(bpy)32+. Further insight into the mechanism of zirconium catalyzed photoredox reactions is provided via a detailed study of the reductive benzyl coupling reaction.

Luminescent zirconium(IV) complexes as a molecular photosensitizers for visible light photoredox catalysis

254th National Meeting (2017)

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