Synthesis and luminescent properties of copper(I) complexes with 3-pyridin-2-yl-5-(4-R-phenyl)-1H-1,2,4-triazoles

Abstract

A series of heteroligand copper(I) complexes with 3-pyridin-2-yl-5-(4-R-phenyl)-1H-1,2,4-triazoles (R = H, CH₃, CH₃O) and PPh₃ of general composition CuIL(PPh₃) have been synthesized and studied. The compounds have been characterized by elemental analysis, IR spectroscopy, and diffusion reflectance spectra. The structure of the complex with 3-pyridin-2-yl-5-phenyl-1H-1,2,4-triazole has been determined by single-crystal X-ray diffraction analysis. The complex is mononuclear and has a tetrahedral environment of the central atom. The compounds exhibit strong visible photoluminescence (λ_max = 599–609 nm). Quantum-chemical calculations at the B3LYP/DGDZVP level have demonstrated that the short phosphorescence life-time of the CuIL(PPh₃) compounds is caused by intensity transfer from the S₀–S₂ transition through spinorbit coupling induced by the rotation of the iodine 5p orbital upon the T₁–S₂ transition.