Investigation on the Effect of Complex Formation on Prominent High Static/Dynamic First and Second Hyperpolarizability of Co(II) Complex Including 4-Chloro Acid

Abstract

Nonlinear optical (NLO) materials with promising first- and second-order hyperpolarizabilities play a crucial role in the fields of electronics and optoelectronics. For the metal-organic coordination complexes, the logical selection of an appropriate ligand and metal ion is vital in designing such materials to enhance their NLO response. In this study, a novel Co(II) complex, including 4-Chloro-pyridine-2-carboxylic acid ligand, was synthesized. The crystal structure and spectroscopic properties were determined by XRD, FT-IR, and UV-Vis spectroscopies. B3LYP and CAM-B3LYP level calculations demonstrated that there is a strong electronic absorption band at 356 nm, originating from the metal-ligand charge transfer (MLCT) transfer in the UV-Vis spectrum. Both XRD and FTIR data demonstrated that the Co(II) complex has a distorted octahedral coordination geometry. The calculations of static and frequency-dependent alpha, beta, and gamma at frequencies of w = 0.0856252 a.u (7 = 532 nm) and w = 0.0428126 au. (7 = 1064 nm) for 4Clpca and Co(II) complex have been also carried out using B3LYP and CAMB3LYP levels. The dc-Kerr effect gamma(-w; w,0,0) and SHG gamma(-2w; w,w,0) parameters for Co(II) complex calculated as 329.59 x 10-36 and 433.93 x 10-36 esu are found as dramatically higher those for single pca ligand (6.0267 x 10-36 and 163.70 x 10-36 esu). So, a significant increase was detected in the parameters of frequency-dependent alpha (-w; 0), beta(-w; w,0), and gamma (-w; w,0,0) with complex formation.