Ethynyl π-coordinated and non-coordinated mononuclear Cu(i) halide diphosphine complexes: synthesis and photophysical studies†
Abstract
Highly emissive copper(I) diphosphine halide complexes and their alkynyl clusters 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(CC), X = I (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 (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 π coordinates with the Cu(I) center. Complexes 4 and 5 emit yellow green delayed fluorescence (λmax = 536–539 nm, τ = 0.43–21.02 μs, and ΦPL = 0.08–0.30%) and complexes 1–3 and 6 and 7 show yellow green to greenish yellow prompt fluorescence (λmax = 549–583 nm, τ = 1.7–11.0 ns, and ΦPL = 0.16–3.43%). The emissions of 1–7 are from the (metal + halide) to the ligand and intra-ligand charge transitions. Complex 4 shows photocatalytic H2 evolution activity under visible-light irradiation.