Electronic structure and UV–Vis spectra simulation of square planar Bis(1-(4-methylphenylazo)-2-naphtol)-Transition metal complexes [M(L)2]x (M = Ni, Pd, Pt, Cu, Ag, and x = − 1, 0, + 1): DFT and TD-DFT study

DFT/B3LYP calculations with full geometry optimizations have been carried out on 1-phenylazo-2-naphthol and their metal complexes of formula M(MePhNap)2 (M = Ni, Pd, Pt, Cu, Ag, and MePhNap = 1-(− 4-methylphenylazo)-2-naphtol) in their neutral, oxidized, and reduced forms. The predicted structures provide to the M(II) metal ions the square planar geometry and distorted azo ligand. The TD-DFT theoretical study performed on the optimized geometry allowed us to predict the UV–Vis spectra and to identify quite clearly the spectral position and the nature of the different electronic transitions according to their molecular orbital localization. Large HOMO-LUMO gaps are calculated for all optimized structures suggesting good chemical stabilities, hence, reproducing the available UV–Vis spectra and compared to that of free ligand. The electronic spectra obtained in DMSO and ethanol polar solvents predict more important red shifts than those obtained in hexane as nonpolar one.