New coordination compounds of some rare-earth metal complexes with sulfur and nitrogen Schiff bases and their in vitro antibacterial and antifungal properties

Abstract

A series of rare-earth metal complexes with Schiff bases have been prepared by the interactions of hydrated lanthanide(III) chloride with the sodium salts of 1-(2-thienyl)ethanone hydrazinecarbothioamide (L¹H) and 1-(2-thienyl)ethanonehydrazinecarboxamide (L²H) in 1:3 molar ratios and characterized by their elemental analyses, molar conductance and IR, NMR (¹H and ¹³C) electronic and EPR spectral studies. The spectral data suggested that the complexes have a hexa-coordinated environment around the central metal atoms. Elemental analyses and NMR spectral data of the ligands and their metal(III) complexes agree with their proposed structures. The synthesized Schiff bases and their new metal complexes have been screened for in vitro antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Pseudomonas cepacicola) bacterial strains and for in vitro antifungal activity against Fusarium oxysporum and Macrophomina phaseolina. All compounds showed significant antibacterial and antifungal activities against microbial species.

Keywords:

• rare-earth elements
• Schiff bases
• EPR spectra
• antibacterial activity
• antifungal activity

Acknowledgements

The authors are thankful to CSIR, New Delhi, India, for financial assistance through Grant No. 01(2307)/09/EMR-II.