Structure-Property Relationships in a New Family of Photoactive Diimine-Diphosphine Copper(I) Complexes.

A new family of heteroleptic diimine-diphosphine copper(I) complexes is reported, with six new complexes compared to benchmark [Cu(bcp)(DPEPhos)]PF . These new complexes are based on 1,4,5,8-tetraazaphenanthrene (TAP) ligands with representative electronic properties as well as substitution patterns and DPEPhos and XantPhos as diphosphine ligands. Their photophysical and electrochemical properties were investigated and correlated with the number and position of substituents on the TAP ligands. Stern-Volmer studies using Hünig's base as reductive quencher demonstrated the influence of the complex photoreduction potential and of the excited state lifetime on the photoreactivity. This study refines the structure-property relationship profile for heteroleptic copper(I) complexes and confirms that such profiles are of high interest to design new copper complexes as optimized photoredox catalysts.