Synthesis, Crystal Structure and Photophysical Properties of Cu(I) Complexes Containing 2,5-Bis(pyridyl)-1,3,4-oxadiazole

Four novel Cu(I) complexes, [Cu(o-PYO)(PPh3)(2)]BF4 (1), [Cu(o-PYO)(DPEphos)]BF4 (2), [Cu-2(o-PYO)(PPh3)(3)(CH3CN)](BF4)(2) (3) and [Cu-2(o-PYO)(DPEphos)2](BF4)(2) (4) (o-PYO = 2,5-bis(pyridy1)-1,3,4-oxadiazole, PPh3 = triphenylphosphine, DPEphos = bis(2-(diphenylphosphanyl)phenyl)ether), have been synthesized and characterized by H-1 NMR, elemental analysis and single-crystal X-ray diffraction. The central cuprous ions in all complexes are surrounded by N and P atoms to form a distorted tetrahedral geometry, although one of the cuprous ions in complex 3 is coordinated by a PPh3 and an acetonitrile molecule due to the steric hindrance and weak coordination ability from monodentate PPh3 ligand. The UV-vis absorption spectra in CH2Cl2 show the characteristic metal-to-ligand charge transfer (MLCT) absorption bands in the region of 360-480 nm. Four Cu(I) complexes exhibit yellow to orange-red phosphorescence with the emission maximum at 572, 577, 562 and 597 nm, respectively in the solid state.