Recyclable iridium-containing copolymers for homogeneous photoredox catalysis

Abstract

Iridium-based polypyridyl complexes have gained recent attention in photoredox catalysis, with the potential for enhanced efficiency across a variety of applications. However, challenges such as poor recyclability, catalyst loss, and high costs can hinder their practical utility. Herein, we report the synthesis and characterization of three poly(methyl methacrylate)s featuring pendant cyclometalated iridium complexes based upon [Ir(df(CF₃)ppy)₂(dmbpy)](PF₆), [Ir(ppy)₂(dmbpy)](PF₆), and fac-Ir(ppy)₃. Our homogeneous polymer catalysts exhibited exceptional performance across a diverse array of photoredox-mediated transformations, including Birch-type photo-reduction, cycloaddition reactions, dual catalytic cross-coupling systems, and regioselective alkene functionalizations, while closely mimicking the catalytic and photophysical properties of their small-molecule counterparts. The new polymer photocatalyst maintained fidelity during reactions, enabling it to be recycled and reused up to at least five cycles. This approach combines high performance with sustainability, offering a promising pathway toward greener photoredox catalysts while broadening the practical applications of iridium-based systems.