Title of Thesis

Organotin (IV) Complexes With o, o donor atoms from carboxylic acid derivatives

Author(s)

Niaz Muhammad

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 (HL1), 4- bNitrophenylethanoic acid (HL2), 4-Chlorophenylethanoic acid (HL3), 3-Methylphenyl ethanoic acid (HL4), 3-(4-Bromophenyl)-2-ethylacrylic acid (HL5), 3-(4-Bromophenyl)-2-methylacrylic acid (HL6), 3-(4-Chlorophenyl)-2-methylacrylic acid (HL7), 3-(4- Chlorophenyl)-2-ethylacrylic acid (HL8), 3-(4-Nitrophenyl)-2-methylacrylic acid (HL9) and 3-(4-Nitrophenyl)-2-ethylacrylic acid (HL10). 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 (1H, 13C and 119Sn) 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 skewtrapezoidal geometry in solid state, however, the coordination around Sn change from six to five in solution, in most cases.
The interaction of (n-C4H9)3Sn(IV)L, (CH3)3Sn(IV)L, (n-C4H9)2(IV)SnL2 and (C2H5)2Sn(IV)L2 (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: (C2H5)2Sn(IV)L2 (8.5 x103) < (n-C4H9)2Sn(IV)L2 (1.11 x 104) < (CH3)3Sn(IV)L (1.39 x 104) < (n- C4H9)3Sn(IV)L (1.46 x 104) M-1.The negative values of ΔG 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 Brine shrimp) than standard drug while only compound 10 was found stronger anticancer agent against human prostate cell lines(PC-3).

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1.1 Organotin compounds
1.2 Organotin compounds overview
1.3 Principal coordination geometries at the tin centre in organotin compounds
1.4 Organotin(IV) carboxylates
1.5 Structural features of organotin(IV) carboxylates
1.6 Structural characterization of organotin(IV) compounds
1.7 Applications of organotin(IV) compounds

2.1 Chemicals
2.2 Instrumentation
2.3 General procedure for the synthesis of ligands
2.4 General procedure for the synthesis of ligand salt
2.5 General procedure for the synthesis of diorganotin(IV) dicarboxylates
2.6 General procedure for the synthesis of di-n-octyltin(IV) dicarboxylates
2.7 General procedure for the synthesis of triorganotin(IV) carboxylates
2.8 Biological applications
2.9 X-ray single crystal analysis

3.1 Use of Picrolonic acid (HPA) in Copmlexation / Extraction
3.2 Use of Crown Ethers in Extraction of REEs
3.1 Synthesis of organotin(IV) carboxylates
3.2 Spectroscopic investigations
3.3 Mass spectrometry
3.4 Evaluation of DNA binding parameters
3.5 Antibacterial and antifungal activities
3.6 Cytotoxicity
3.7 Anticancer activity

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4.1 X-ray structure of (HL5), (HL6), (HL7), (HL9) and (HL10)
4.2 X-ray structure of triorganotin(IV) carboxylates
4.3 X-ray structure of diorganotin(IV) dicarboxylates