Synthesis, Spectroscopic Characterization and Antibacterial Assessment of Zirconium(II) and Palladium(II) Complexes of Tetracycline-Salicylaldehyde Mixed Ligand

Abstract

Zirconium(II) and palladium(II) mixed ligand metal complexes were synthesized by using an equimolar mixture of tetracycline (Tc) as primary ligand and salicylaldehyde as secondary ligand. The metal complexes were characterized by physico-chemical and spectroscopic techniques like CHN analysis, surface tension, pH, conductivity and melting point measurements. The spectroscopic characterization technique includes IR, (¹H & ¹³C) NMR, UV/visible and Mass spectrometry methods. The SEM technique determines the surface morphology of the complexes. The thermal and kinetic stability of the complexes was obtained from TGA/DTA curves from which the parameters like E^*, ΔH^*, ΔS^* and ΔG^* have been calculated by using the Coats-Redfern equation. Molecular modeling gives a geometry of the complex which was obtained from Chem 3D Pro. 12.0 software program. The metal complexes of Zr-TcSal and Pd-TcSal have coordinated with tetrahedral and square planar geometry, respectively. The antibacterial susceptibility study of the synthesized metal complexes was done by Kirby-Bauer paper disc diffusion techniques on S. aureus, E. coli and P. aeruginosa clinical pathogens.