Synthesis, crystal structure, spectroscopic, and biological studies on Cu(II) complexes of N,O donor dimethyl isoxazole Schiff bases

Abstract

Cu(II) complexes with Schiff bases DMIIMP, DMIIMBD, DMIIMBP, DMIIMCP, DMIIMMP, and DMIIMNP (see Introduction for definitions) are derived from condensation of 3,4-dimethyl 5-amino-isoxazole with salicylaldehyde and substituted salicylaldehydes. The newly synthesized ligands were characterized by IR, UV-Vis, ¹H NMR, ¹³C NMR, mass spectra, and elemental analysis. The Cu(II) complexes were characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, thermogram, DTA, and single crystal analysis. The complexes have general formula [M(L)₂]. The Schiff bases are bidentate coordinating through the azomethine nitrogen and phenolic oxygen of salicylaldehydes. Based on the analytical and spectral data, four-coordinate geometry is assigned for all the complexes. ESR and single crystal analysis suggests square planar geometry for all complexes. [Cu(DMIIMP)₂] crystallizes in the orthorhombic system. Antimicrobial studies of Schiff bases and their metal complexes show significant activity with the metal complexes showing more activity than corresponding Schiff bases. Cytotoxicity of the copper complexes on human cervical carcinoma cells (HeLa) was measured using the Methyl Thiazole Tetrazolium assay.

Keywords:

• Isoxazole Schiff base
• Cu(II) complexes
• Single crystal
• Square planar
• Antimicrobial activity

Acknowledgments

The authors are grateful to the Head, Department of the Chemistry for providing the necessary facilities. The authors are thankful to the Director, CFRD, Osmania University, Hyderabad and the Director, IICT, Hyderabad for providing spectral and analytical data. The authors are also thankful to UGC, New Delhi for providing financial assistance.