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)]BF4 (1), [Cu(dpq)(xantphos)]I (2), [Cu(dpq)(dppp)]BF4 (3), [Cu(dppz)(dppp)]BF4 (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, H-1 NMR, P-31 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 center dot center dot center dot pi it interactions lead to the formation of a ID infinite chain structure. Interestingly, complexes 1-5 show novel 2D or 3D network structures through C-H center dot center dot center dot pi 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 mu s. The terahertz (THz) time-domain spectra of these complexes were also studied. (C) 2019 Elsevier Ltd. All rights reserved.