Synthesis, Thermal Characterization and in vitro Antibacterial Assessment of Co(II) and Cd(II) Complexes of Schiff Base Derived from Amoxicillin and Thiophene-2-carbaldehyde

Abstract

A novel AMXTC2 ligand was prepared by simultaneous stirring and refluxing of an equimolar mixture of amoxicillin and thiophene-2-carbaldehyde in methanol and was further used to synthesize metal complexes by metalation with cobalt and cadmium salts, taking ligand metal ratio 2:1. They were characterized by elemental microanalysis, FT-IR, mass, UV-visible, 1H NMR, thermal analysis, magnetic moment and molar conductance measurements. The coordination sites in the ligand were verified by their comparative and extensive spectral studies. The detailed exploration of the data suggested octahedral geometry for Co-AMXTC2 and tetrahedral geometry for Cd-AMXTC2 complexes. The thermodynamic and kinetic parameters such as E*, ΔH*, ΔS* and ΔG* of various decomposition steps were calculated from TGA curves using the Coats-Redfern method. The molar conductivity data suggested non-electrolytic nature of the complexes. SEM analysis was done to observe their surface morphology. The geometry optimization of the proposed molecular structure of the complexes was achieved by running MM2 calculation in Gaussian supported Cs-ChemOffice Ultra-11 program software. The biological activities had been evaluated in vitro against E. coli, K. pneumonia, P. vulgaris and S. aureus pathogens in order to assess their antibacterial potency. The biological data revealed better growth inhibitory action of the ligand and metal complexes with bacterial pathogens.

Thiophene‐containing compounds with antimicrobial activity

“…Antibiotic amoxicillin was condensed with thiophene‐2‐carboxaldehyde to give azomethine 234 (Figure 27), which was then employed as ligand in the generation of complexes derived from either cobalt chloride or cadmium chloride. [ 211 ] The strains of E. coli , K. pneumoniae and P. vulgaris used in this study proved resistant to amoxicillin, but not to the action of ligand 234 and its complexes. These bacterial strains appear to be most sensitive to the cadmium complex of 234 .…”

“…Antibiotic amoxicillin was condensed with thiophene-2carboxaldehyde to give azomethine 234 (Figure 27), which was then employed as ligand in the generation of complexes derived from either cobalt chloride or cadmium chloride. [211] The strains of E. coli, K.…”

Bis{2,6-bis[(E)-(4-fluorobenzylimino)methyl]pyridine}nickel(II) dinitrate dihydrate

“…Schiff bases containing molecular clefts with multiple donor atoms are attractive chelating ligands in the area of coordination chemistry. The incorporation of transitionmetal ions within the Schiff base-derived molecular frameworks can make them potentially useful in a number of biomedical allocations (Chaudhary & Guragain, 2019). Because of the excellent chelating properties of Schiff bases derived from multidentate ligands, they are widely used to coordinate transition-metal ions (Guerriero et al, 1992;Vigato & Tamburini, 2004;Gupta & Sutar, 2008; da Silva et al, 2011).…”

Synthesis, spectroscopic determination and in vitro antimicrobial studies of cobalt(ii) and nickel(ii) complexes of a Schiff base derived from 1h-indole-2,3- dione with hydrazinecarbothioamide

“…Schiff base is a condensation product of an amine and carbonyl compounds, and are important class of ligand that coordinate to metal ions through N, O and S donor atoms. (Chaudhary, 2013). Formation of Schiff base therefore involves chemistry of C=N functional group.…”