Synthesis, Spectroscopic Characterization, and Antifungal Activity of Some Mixed Ligand Complexes of Zn(II), Cd(II), and Hg(II)

Abstract

A series of new mixed ligand complexes of Zn(II), Cd(II), and Hg(II) with citronellal thiosemicarbazone [3,7-dimethyl-6-octene-1-a1 thiosemicarbazone (LH)] and N-phthaloyl amino acids (AH) have been synthesized by the reaction of metal(II) chloride with ligands citronellal thiosemicarbazone (DOTSC) and N-phthaloyl glycine [1,3-dihydro-1,3-dioxo-2H-isoindole-2-acetic acid (A₁H)] or N-phthaloyl alanine [1,3-dihydro-1,3-dioxo-α(methyl)-2H-isoindole-2-acetic acid (A₂H)] in 1:1:1 molar ratio in dry refluxing ethanol. All the complexes have been characterized by elemental analyses, molar conductance measurement, molecular weight measurement, IR, and multinuclear NMR (¹H and ¹³C{¹H}) spectral studies. IR, ¹H, and ¹³C{¹H} NMR spectral studies suggest the involvement of azomethine-N, thiol-S atoms of the thiosemicarbazone moiety and both carboxylate-O of N-phthaloyl amino acid moiety in coordination with central metal(II) ion, and four coordinated geometries have been assigned to these complexes. The free ligands and metal complexes have been screened for their antifungal activity against two fungal strains, Fusarium moniliformae and Macrophomina phaseolina, using the the radial growth method. The results of antifungal activity show that metal complexes show enhanced higher activity than the free ligands.

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Keywords:

• Antifungal activity
• radial growth method
• thiosemicarbazone

Acknowledgments

The authors are greatly indebted to Prof. A. K. Bhargava and Prof. A. K. Mathur, Department of Plant Pathology, Agriculture Research Station, Durgapura, Jaipur, for the help in antifungal screening. One of the authors (RS) is grateful to CSIR, New Delhi, for providing a Senior Research Fellowship to her. The authors are also thankful to the CDRI, Lucknow, for recording elemental analysis.

Notes

d = Dec.

^a Molar conductance determined at 298 K in 10⁻³ M DMF solution.