Structural properties, antimicrobial and anticancer potency of new organotin(IV) dithiocarboxylates
Zia-ur-Rehman
Faculty member
Department of Chemistry,
Quiad-i-Azam University,
Islamabad-45320,
Pakistan
Abstract:
Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates with the general formulae, R3Sn(S2C-subsituted piperazine), R2Sn(S2C-subsituted piperazine)Cl and R2Sn(S2C-substituted piperazine)2, have been synthesized by the reactions of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratios. Elemental analysis, Raman, IR, multinuclear NMR (1H, 13C and 119Sn) and X-ray crystallographic studies have been undertaken to elucidate the structures of the complexes, both in solution and in the solid state. There is a wealth of structural data available for these compounds, with the exception of the diorganotin bis(dithiocarboxylate) compounds, R2Sn(S2CNR´2)2. In the compounds for which different structural motifs are evident, there is a certain degree of homogeneity in the molecular structures for each class of compound unless there are additional coordination sites available on the R and/or R´ groups. Owing to the strong coordination potential of the dithiocarboxylate ligand for tin, supramolecular aggregates involving secondary Sn---S interactions are the exception rather than the norm (Fig. 1). The DNA-binding study of selective complexes by cyclic voltammetry (CV) (Fig. 2) and UV-Vis spectroscopy (Fig. 3) attested them to be good DNA-binders with intercalative modes of interaction. The DNA-binding ability of these complexes can be attributed to their potential to form secondary intermolecular interactions with DNA. A subsequent antimicrobial study indicates that the compounds are active biologically and may well be the basis for a new class of antimicrobial metal-based drugs.
Fig. 1. Supramolecular zig-zag chain in the structure of compound mediated by secondary Sn---S and benzyl-C---H interactions
Fig. 2. CV behavior of 3 mM compound at clean GC electrode in the absence and presence of 60 µM DNA (b) in 10% aqueous DMSO using 0.1 M TBAFB as supporting electrolyte at 0.1 V/s scan rate.
Fig. 3. Absorption spectra of 30 mM compound in the absence (a) and presence of 20 µM, (b) 30 µM, (c) 40 µM, (d) 50 mM, (e), 60 µM (f), 70 µM (g) and 80 µM DNA (h) in 10% aqueous DMSO at 25 oC.
