Synthesis, antimicrobial screening, and DNA-binding/cleavage of new pyrazole-based binuclear Co^II, Ni^II, Cu^II, and Zn^II complexes

Abstract

Pyrazolato endogenous bridged binuclear Co^II, Ni^II, Cu^II, and Zn^II complexes were prepared and characterized by spectro-analytical methods. The hexadentate N₄S₂ donor was synthesized by condensation of 3,5-dichloroformyl-1H-pyrazole with thiosemicarbazide in dry ethanol. All the complexes were binuclear and octahedral in nature. The ligand and complexes are screened for antimicrobial and DNA-binding/cleavage activities. The binding/cleavage activities with Escherichia coli DNA are monitored with absorption, hydrodynamic, thermal denaturation, and electrophoresis studies. The ligand possesses significant activity against microbes which is further enhanced upon complexation. The DNA-binding study reveals classical intercalation. The Ni^II and Cu^II complexes exhibit higher binding ability.

Keywords:

• Pyrazole
• Thiosemicarbazide
• Antimicrobial activity
• DNA-binding study
• Intercalation

Acknowledgments

The authors thank the Department of Chemistry and USIC, Karnatak University, Dharwad, for providing spectral and analytical facility. Recording of FAB mass spectra (CDRI Lucknow) and EPR spectrum (IIT Bombay) are gratefully acknowledged. The author NVK thanks Karnatak University, Dharwad for providing Nilekani Fellowship.