Experimental and theoretical approaches on structural, spectroscopic (FT-IR and UV-Vis), nonlinear optical, and molecular docking analyses for Zn (II) and Cu (II) complexes of 6-chloropyridine-2-carboxylic acid

Novel transition metal-based complexes that may be of value as biological agents and/or nonlinear optical materials, Zn (II) and Cu (II) transition metal complexes of 6-chloropyridine-2-carboxylic acid (LH), were successfully synthesized. The chemical structure of each complex was characterized using X-ray diffraction (XRD) method and FT-IR spectroscopy. XRD and FT-IR demonstrated that L ligand coordinate to central metal ions through the donor N and O atoms. By coordinating two H2O ligand to Zn (II) ion, a distorted octahedral complex geometry was constructed for 1. As for 2, a distorted trigonal bipyramidal coordination geometry was obtained by a H2O ligand coordination to Cu (II) ion. Theoretical studies using B3LYP/6-311++G(d,p)-LanL2DZ were performed to further validate the proposed structures. The molecular docking of 1 to SARS-CoV-2 main protease (PDB: 6LU7) gives a binding energy of -5.24 kcal/mol and inhibition constant of 144.6 mu M, demonstrating that 1 is a more promising candidate to biologically active complexes than 2. The first-order hyperpolarizability (beta) parameter for 1 and 2 was calculated as 0.88 x 10(-30) and 10.40 x 10(-30) esu, respectively. These beta values also demonstrated that 2 exhibits more effective NLO character than 1 due to the electronic configuration and coordination geometry.

Automated summary

Novel transition metal-based complexes of 6-chloropyridine-2-carboxylic acid (LH) were successfully synthesized and characterized. The complexes showed potential as biological agents and exhibited nonlinear optical properties, with one complex demonstrating higher biological activity and the other having stronger nonlinear optical character.