Copper(I) complexes with remotely functionalized phosphine ligands: Synthesis, structural variety, photophysics and effect onto the optical properties

The synthesis, chemical and photophysical investigation of a series of eight novel copper-halide derivatives with different nuclearity is herein presented. One mononuclear copper(I) complex with formula [CuI(pyridine)(P)2], where P is a functionalized phosphine, six dinuclear derivatives bearing the rhombic {Cu2I2} subunits and with general formula [Cu(μ-I)(P)(N)]2 (N = pyridine, quinoline and 4-cyanopyridine) as well as one tetranuclear copper-iodide clusters of general formula [Cu(μ-I)P]4 consisting of a cubane-like {Cu4X4} motif were straightforwardly prepared, also by means of mechano-chemical synthetic procedure. The phosphine ligands were prepared in excellent yield by using simple hydrophosphination reactions. For five of the investigated cuprous iodide derivatives their atom connectivity and solid-state crystalline packing was unambiguously confirmed by solving their single-crystal X-ray structure. All the investigated complexes resulted into photo- and thermally-stable luminescent species. In the solid state as microcrystalline powder samples, the complexes display intense photoluminescence ranging from the sky-blue to orange-red portion of the spectrum with PLQY values of 0.28–0.50 and 0.34–0.97 at room and low (77 K) temperature, respectively, depending on the nature of both the coordinated N-heteroaromatic ring and phosphine ligands. In spite of the remote location of the functionalization of the phosphine, profound effects are observed onto the solid-state emission properties highlighting the importance of microenvironment for the emitters in the aggregated phase.