Calculation of the optical spectra of the copper(I) complex with triphenylphosphine, iodine, and 3-pyridine-2-yl-5-phenyl-1H-1,2,4-triazole by the DFT method

Abstract

The IR and UV spectra of the [CuIL(PPh₃)] complex (PPh₃ = triphenylphosphine, L = 3-pyridine- 2-yl-5-phenyl-1Н-1,2,4-triazole) have been analyzed in detail within the density functional theory (DFT) and its time-dependent version TD DFT. The standard functional B3LYP and sets of basis orbitals 6-311G(d,p) and Lanl2DZ are used for the atoms of the elements of periods I and II and for the iodine atom, respectively. The calculated IR spectra of the complex and free ligands coincide with the observed IR bands, due to which one can completely interpret all normal modes and confirm X-ray diffraction (XRD) data. Particular attention is paid to the structure of excited triplet (Т₁) state in order to explain the role of copper and iodine ions in the formation of photo- and electroluminescence spectra. It is shown that the equilibrium Т₁ state undergoes structural relaxation after the vertical excitation and significantly changes its electronic nature and the charge transfer structure.