Ethynyl pi-coordinated and non-coordinated mononuclear Cu(I) halide diphosphine complexes: synthesis and photophysical studies

Highly emissive copper(i) diphosphine halide complexes and their alkynyl dusters have attracted great attention, but mononuclear copper(i) halide alkynyl diphosphine complexes and their photophysical properties are rarely reported. Here, seven mononuclear copper(i) halide ethynyl diphosphine complexes, CuX(L1), CuX(L2) and CuX(L3) [L1 = (2-PPh2-C6H4)(2)(C C), X = 1(1), B (2), Cl (3); L2 = (4,5-OMe-2-PPh2-C6H2)C C(2-PPh2-C6H4), X = I (4), Br (5), Cl (6); and L3 = (4,5-OMe-2-PPh2-C6H2)(2)(C C), X = I 1(7)], were successfully prepared and their structures and photophysical properties were systematically characterized. In 1-3, ethynyl is non-coordinated with Cu(I), while in 4-7, ethynyl Tc coordinates with the Cu(i) center. Complexes 4 and 5 emit yellow green delayed fluorescence (lambda(max)= 536-539 nm, tau = 0.43-21.02 mu s, and Phi(PL) = 0.08-0.30%) and complexes 1-3 and 6 and 7 show yellow green to greenish yellow prompt fluorescence (lambda(max )= 549-583 nm, tau = 1.7-11.0 ns, and Phi(PL) = 0.16-3.43%). The emissions of 1-7 are from the (metal + halide) to the Eigand and intra-Eigand charge transitions. Complex 4 shows photocataIytic H-2 evolution activity under visible-light irradiation.