Synthesis, spectral properties and terahertz time domain spectroscopy of two copper(I) complexes based on bisphosphine and bisazo ligands

Two copper(I) complexes, [Cu(bdppmapy)(BTZ)]BF4 (1) and [Cu(bdppmapy)(BTZ)]ClO4 (2) (bdppmapy = N,N-bis[(diphenylphosphino)methyl]-2-pyridinamine, BTZ = 2,2-bithiazole), have been synthesized in mixed CH3OH and CH2Cl2 (1:1, V/V) and characterized by single-crystal X-ray diffraction, elemental analysis, IR, 1H NMR and 31P NMR spectroscopy, fluorescence spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 1, a mononuclear complex, was generated by the reaction of [Cu(CH3CN)4]BF4 and bdppmapy with BTZ in a 1:1:1 molar ratio. In 1, the center Cu(I) forms a distorted tetrahedral geometry by coordinating with the diphosphine ligand (bdppmapy) and N-ligands BTZ. Complex 2 was obtained by reacting [Cu(CH3CN)4]ClO4 and bdppmapy with BTZ in a 1:1:1 molar ratio. In 2, the bdppmapy and BTZ ligands chelate Cu(I). Luminescent spectra show that the emission mechanism is ascribed to metal-to-ligand charge transfer (MLCT). Terahertz time-domain spectroscopy was also used to characterize these two complexes.