A multiprotic ditopic thiocarbohydrazone ligand in the formation of mono- and di-nuclear organotin(IV) complexes: Crystal structure, antibacterial activity and DNA cleavage

Abstract

Three organotin(IV) complexes, Ph4Sn2L (1), Me2Sn(H2L) (2) and Bu2Sn(H2L) (3) have been formed from reaction of R2SnCl2 (R = Ph, Me and Bu) with a multiprotic dihydrazone, 1,5-bis((2-hydroxynaphthaldehyde) thiocarbohydrazone (H4L). The synthesized compounds have been investigated by elemental analysis, IR, 1H NMR, and 119Sn NMR spectroscopy. The structure of 1 has been also confirmed by X-ray crystallography. The results show 1 is binuclear and fully deprotonated thiocarbohydrazone supplies two different tridentate dianionic domains, NNO and ONS, for coordination to two diphenyltin(IV) moieties. Coordination number of both tin(IV) center is five and it is maintain in solution. In 1 and 2 only one part of ligand as doubly deprotonated ONS donor was coordinated with tin and a mononuclear organotin complex with coordination number of five was formed. The in vitro antibacterial activity of ligand and complexes has been evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (E. coli and P. aeruginosa) bacteria and compared with standard drugs. The synthesized compounds also have been investigated for the chromosomal and plasmid DNA cleavage activity. All complexes significantly inhibited bacterial growth and completely degrade the treated DNA.