Synthesis, characterization, thermal investigation, and antimicrobial activity of some new bis-imine cadmium (II) complexes

In this article, the Schiff bases ligand of N۱,N۴-bis((E)-۳-(۲-methoxyphenyl)allylidene)butane-۱,۴-diamine(L) and its cadmium complexes with the general formula CdLX۲, (X = Cl-, Br-, I-, SCN-) were synthesized. The compounds were characterized using physical and spectroscopic techniques such as IR, ۱H NMR, ۱۳C NMR, UV-visible, molar conductivity and melting point measurements. The ligand is coordinated as bidentate ligand via imine nitrogens and its complexes have pseudo tetrahedral geometry. Additionally, the thermal behaviors of the ligand and its complexes were investigated based on TG/DTG/DTA plots. The thermal stability of all compounds and the thermo-kinetic activation parameters of the decomposition processes, including activation energy (∆E*), Gibbs -free energy (∆G*), enthalpy (∆H*) and entropy (∆S*) in each stage of decomposition processes were calculated based on TG/DTA plots using Coats–Redfern relation. Typically, the CdLBr۲ complex was synthesized in nanostructured form confirmed by SEM and XRD analysis. Then the nanostructured CdLBr۲ complex was used as a precursor for the preparation of cadmium oxide nanoparticles. Furthermore, the antibacterial and antifungal properties of the ligand and all synthesized complexes against two fungi (Aspergillus aurinosa and Candida albicans), two strains of Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two strains of Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) were evaluated in the laboratory environment using the well diffusion method. Among the compounds, cadmium chloride and bromide were found as the best antimicrobial agents. Additionally, interaction of the compounds with DNA showed that the cadmium chloride complex have the greatest effect in degrading and cleaving DNA.

Keywords:

Synthesis , Schiff base , Cadmium (II) complexes , antibacterial , Antifungal