Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of Co(II)- picolinate complex

Abstract

A cobalt(II) complex of picolinate was synthesized, and its structure was fully characterized by the applying of X-ray diffraction method as well as FT-IR, FT-Raman and UV–vis spectroscopies. In order to both support the experimental results and convert study to more advanced level, density functional theory calculations were performed by using B3LYP level. Single crystal X-ray structural analysis shows that cobalt(II) ion was located to the center of distorted octahedral geometry. The CO, CC and CN stretching vibrations were found as highly active and strong peaks, inducing the molecular charge transfer within Co(II) complex. The small energy gap between frontier molecular orbital energies was another indicator of molecular charge transfer interactions within Co(II) complex. The nonlinear optical properties of Co(II) complex were investigated at DFT/B3LYP level, and the hypepolarizability parameter was found to be decreased due to the presence of inversion symmetry. The natural bond orbital (NBO) analysis was performed to investigate molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength for Co(II) complex. Finally, molecular electrostatic potential (MEP) and spin density distributions for Co(II) complex were evaluated.