Synthesis, structures and photophysical properties of polynuclear copper(I) iodide complexes containing phosphine and 4,4′-bipyridine ligands

Abstract

The highly luminescent polynuclear Cu I iodide complexes, [(Cu 2I 2)(4,4′-bipy)(PCy 3) 2] 2 · 4H 2O ( 1), [(Cu 2I 2)(4,4′-bipy)(PCy 3) 2] ∞ ( 2), [(Cu 2I 2)(4,4′-bipy)(dcpm)] ∞ ( 3) and [(Cu 2I 2)(4,4′-bipy)(dppm)] ∞ ( 4), were prepared by reacting CuI with tricyclohexylphosphine (PCy 3), bis(dicyclohexylphosphino)methane (dcpm) or bis(diphenylphosphino)methane (dppm) and 4,4′-bipyridine (4,4′-bipy), and their structures were determined by X-ray crystal analysis. The reported complexes [CuClPCy 3] 2 ( 5) and [CuIPCy 3] 2 ( 6) were also prepared for comparison. In solid state, complexes 1– 6 display intense long-lived phosphorescence with λ max at 605, 565, 640, 570, 430 and 450 nm at room temperature, and the solid-state emission quantum yields are 0.11, 0.20, 0.29, 0.35, 0.67 and 0.83, respectively. The relatively high-energy emissions of 5 and 6 are attributed to arising from metal-centered MC (3d → 4s, 4p) excited state, while the low-energy emissions of 1– 4 are assigned to a metal-to-ligand charge transfer (d → π ∗ MLCT) excited state.