Structural, spectroscopic and DFT theoretical studies of phosphorescent CuIP2S-containing cuprous complexes

Luminescent cuprous complexes are important coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The structures of two CuIP 2 S-type cuprous complexes, namely, iodido(thiourea-κ S )bis(triphenylphosphane-κ P )copper(I), [CuI(CH 4 N 2 S)(C 18 H 15 P) 2 ] or [CuI(TU)(TPP) 2 ] ( I ), and (2,3-dihydrobenzimidazole-2-thione-κ S )iodidobis(triphenylphosphane-κ P )copper(I), [CuI(C 7 H 6 N 2 S)(C 18 H 15 P) 2 ] or [CuI(DHBIT)(TPP) 2 ] ( II ), are described. In these two structures, the complex molecules of both are constructed by one copper(I) centre, one iodide ion, two TPP ligands and one thione ligand (TU for I and DHBIT for II ). The copper(I) centres of I and II are both located in a distorted CuIP 2 S tetrahedron and are coordinated by two P atoms from two TPP ligands, one S atom from the thione ligand and the I atom. The UV–Vis absorption and photoluminescence properties of these CuIP 2 S-type cuprous complexes have been studied using crystalline powder samples. Detailed time-dependent density functional theory (TD-DFT) calculations and wavefunction analysis reveal that the pale-blue–green phosphorescence emission should originate from intra-ligand (TPP for I and DHBIT for II ) charge transfer, with a small component of the metal-to-ligand charge transfer 3 (IL+ML)CT excited state.