Organotin(IV) Complexes With O’O Donor Atoms From Carboxylic Acid Derivatives

Abstract

In the present study, a series of tri- and diorganotin(IV) carboxylates have been synthe sized by the reaction of tri- and diorganotin(IV) chlorides/oxides with substituted phenylethanoic acids/salts and α-alkyl cinnamic acids/salts in dry toluene under reflux condition for 8-10 h. The ligands used were 4-Methoxyphenylethanoic acid (HL 1 ), 4- Nitrophenylethanoic acid (HL 2 ), 4-Chlorophenylethanoic acid (HL 3 ), 3-Methylphenyl ethanoic acid (HL 4 ), 3-(4-Bromophenyl)-2-ethylacrylic acid (HL 5 ), 3-(4-Bromophenyl) -2-methylacrylic acid (HL 6 ), 3-(4-Chlorophenyl)-2-methylacrylic acid (HL 7 ), 3-(4- Chlorophenyl)-2-ethylacrylic acid (HL 8 ), 3-(4-Nitrophenyl)-2-methylacrylic acid (HL 9 ) and 3-(4-Nitrophenyl)-2-ethylacrylic acid (HL 10 ). The composition, coordination mode of ligands, structural confirmation and geometry assignment of the complexes in solid and in solution states were made by different analytical techniques such as elemental analysis, FT-IR, multinuclear ( 1 H, 13 C and 119 Sn) NMR, mass spectrometry and X-ray single crystal analysis. Based on these results, the ligand appeared to coordinate the Sn atom via COO moiety. The triorganotin(IV) derivatives demonstrate polymeric trigonal bipyramidal geometry in solid state and a monomeric tetrahedral structure in solution. The diorganotin(IV) dicarboxylates have shown a distorted octahedral or skew- trapezoidal geometry in solid state, however, the coordination around Sn change from six to five in solution, in most cases. The interaction of (n-C 4 H 9 ) 3 Sn(IV)L, (CH 3 ) 3 Sn(IV)L, (n-C 4 H 9 ) 2 (IV)SnL 2 and (C 2 H 5 ) 2 Sn(IV)L 2 (where L = 4-nitrophenylethanoate) with DNA was investigated by cyclic voltammetry (CV). The positive peak potential shift in CV evidenced intercalative mode of interaction of these complexes with DNA. The CV results revealed the following increasing order of binding strength: (C 2 H 5 ) 2 Sn(IV)L 2 (8.5 x 10 3 ) < (n-C 4 H 9 ) 2 Sn(IV)L 2 (1.11 x 10 4 ) < (CH 3 ) 3 Sn(IV)L (1.39 x 10 4 ) < (n- C 4 H 9 ) 3 Sn(IV)L (1.46 x 10 4 ) M -1 . The negative values of ∆G designate the spontaneity of complex-DNA binding. Most of the synthesized complexes were screened for their antibacterial and antifungal activities against various medically important bacteria and fungi. The triorganotin(IV) derivatives have strong bactericidal and fungicidal action than diorganotin(IV) complexes with few exceptions. Some of the compounds were found to have antimicrobial activity comparable or even more than reference drugs and may be used as drugs in future. Some complexes have shown higher cytotoxicity(against iiBrine shrimp) than standard drug while only compound 10 was found stronger anticancer agent against human prostate cell lines(PC-3).