Synthesis, structure and spectroscopic studies of a series of neutral cu(II) complexes of N2O2 coordinating optically active amino alcohol receptor

Abstract

This work focuses on the synthesis and characterization of a series of three optically active amino alcohol reduced Schiff base Cu(II) complexes using a combined experimental and theoretical approach. The synthesized ligands and complexes were characterized through various spectroscopic techniques, including elemental analysis, ¹H NMR, IR, ESI-MS, and UV–vis spectroscopy. Additionally, the X-ray structure of one complex has been reported. The optimization results indicate that the Cu(II) center in the studied complexes has a distorted square pyramidal geometry (with a τ value of approximately 0.3). Furthermore, the electronic excitation energies of the Cu(II) complexes were calculated using time-dependent density functional theory in the solution phase. The TDDFT method was employed to analyze the nature of the highly intense and well-resolved bands observed in the complexes. The electrochemical behaviors of the complexes were investigated through cyclic voltammetry, revealing similar behavior among all the complexes. They exhibited a pair of current peaks in the voltage range of −0.5 to +1.5 V. The paramagnetic complexes were subjected to EPR spectroscopy at 77 K in MeCN, which showed an axial symmetric system (²B_1g) of square pyramidal coordination around the metal center in the EPR spectra of the pentacoordinated Cu(II) complexes.