Heteroleptic Cu(I) complexes with aromatic diimines and phosphines: Synthesis, structure, photophysical properties and THz time domain spectroscopy

Abstract Nine novel copper(I) complexes with diphosphine and diimine ligands, namely [Cu(dpq)(xantphos)]BF 4 ( 1 ), [Cu(dpq)(xantphos)]I ( 2 ), [Cu(dpq)(dppp)]BF 4 ( 3 ), [Cu(dppz)(dppp)]BF 4 ( 4 ), [Cu(dppz)(dppp)]I ( 5 ), [Cu(dppz)(pop)]I ( 6 ), [Cu(dpq)(pop)]I ( 7 ), [Cu(dpq)(pop)]Br ( 8 ), [Cu(dpq)(pop)]SCN ( 9 ) (dpq = pyrazino[2,3-f][1,10]phenanthroline, dppz = dipyrido[3,2-a:2′,3′-c]phenazine, xantphos = 9,9-dimethyl-4,5-bis(diphenylphosphanyl)xanthene, dppp = 1,3-bis(diphenylphosphino)propane, pop = 1,1′-[(Oxydi-2,1-phenylene)]bis[1,1-diphenylphosphine]), were characterized by single crystal X-ray diffraction, IR, elemental analysis, 1 H NMR, 31 P NMR, fluorescence spectra and terahertz time domain spectroscopy (THz-TDS). These nine complexes were synthesized by the reactions of copper salts, diimine ligands and various of P-donor ligands through one-pot method. Single crystal X-ray diffraction reveals that complex 9 is of a simple mono-nuclear structure while complexes 6 and 7 are of dimer structures. For complex 8 , hydrogen bonds and C H⋯π interactions lead to the formation of a 1D infinite chain structure. Interestingly, complexes 1 – 5 show novel 2D or 3D network structures through C H⋯π interactions. In addition, complexes 1 – 3 and 6 – 9 exhibit interesting fluorescence in the solid state at room temperature. Among the nine complexes, complex 1 shows the highest quantum yield up to 37% and the lifetime of 1 is 6.0 μs. The terahertz (THz) time-domain spectra of these complexes were also studied.