Syntheses, Spectral, and Biological Studies of New Imines Derived From 5-Bromothiophene-2-Carboxaldehyde and Their Si(IV), Sn(IV) Complexes

Abstract

The Schiff bases (imines) HL¹ and HL² have been synthesized by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-1,2,4-triazole and 4-amino-3-ethyl-5-mercapto-1,2,4-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes having the general formulae R₂MCl(L¹), R₂MCl(L²), R₂M(L¹)₂, R₂M(L²)₂, (M = Si, Sn; R = CH₃) were synthesized by the reaction of R₂MCl₂ with these Schiff bases in 1:1 and 1:2 molar ratio. The Schiff bases and their metal complexes have been characterized with the aid of elemental analyses, molar conductance, and spectroscopic studies, including UV, IR, ¹H, ¹³C, MS, ²⁹Si, and ¹¹⁹Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. In vitro activities of the Schiff bases and their metal complexes against some Gram positive and Gram negative bacteria and fungi have been carried out and described.

GRAPHICAL ABSTRACT

Keywords:

• 4-Amino-5-mercapto-s-triazole
• Schiff-bases
• silicon-complexes
• tin-complexes
• antimicrobial activity

Acknowledgments

The financial assistance from UGC, New Delhi, vide Major Research Project F. No. 34-317/2008(SR), provided Project fellowship to one of the author (Parvesh Puri) is gratefully acknowledged. The authors would also like to thank the Head of SAIF, IIT-Bombay and the Head of SAIF, CDRI, Lucknow, for providing metal NMR and elemental analyses.

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