Synthesis, crystal structure and photoluminescence of phosphorescent copper (I) complexes containing hole-transporting carbazoly moiety

Two new mononuclear Cu(I) complexes based on 2-(2′-pyridyl)benzimidazolyl derivative ligand containing hole-transporting carbazole ( L ), [Cu(L)(DPEphos)](BF 4 ) and [Cu(L)(PPh 3 ) 2 ](BF 4 ), where L   =   (4-(9 H -carbazol-9-yl)phenyl)methyl-2-(2′-pyridyl)benzimidazole; DPEphos   =   bis[2-(diphenylphosphino)phenyl]ether and PPh 3   =   triphenylphosphine, have been synthesized and characterized on the basis of elemental analysis, 1 H NMR and FT-IR spectra. The structures of the ligand L and the Cu(I) complexes were characterized by single crystal X-ray diffraction. The results reveal that in the Cu(I) complexes the central Cu(I) ions assume the irregular distorted tetrahedral geometry and are tetra-coordinated by the two nitrogen atoms from L ligand and two phosphorus atoms from ancillary ligands. The photophysical properties of the complexes were examined by using UV–vis, photoluminescence spectroscopic analysis. The complexes exhibit weak MLCT absorption bands ranging from 360 to 480   nm, and display strong orange phosphorescence in the solid states at room temperature, which is completely quenched in solutions.