Synthesis and Characterization of Organotin(IV) Complexes Derived of 3-(Dimethylamino)benzoic Acid: Cytotoxic Assay on Human Liver Carcinoma Cells (HepG2)

Problem statement: Many studies have been carried out on organotin(IV) complexes derivative of carboxylate anions. However, the synthesis and characterization as well as the cytotoxic assay of organotin(IV) carboxylate derived of 3-(dimethylamino)benzoic acid have not been studied. Approach: Organotin(IV) carboxylate complexes derivative of 3-(dimethylamino)benzoic acid, 3-[N(CH₃)₂]C₆H₄COOH have been successfully synthesized. Two types of diorganotin(IV) complexes, [{3-[N(CH₃)₂]C₆H₄COO(R)₂Sn}₂O]₂ dimer (R = methyl 1, butyl 3) and {3-[N(CH₃)₂]C₆H₄COO}₂(C₄H₉)₂Sn, 2 (monomer) as well as 3-[N(CH₃)₂]C₆H₄COO(C₆H₅)₃Sn, 4 were successfully synthesized and obtained in solid state. The acid and complexes 1-4 obtained were characterized quantitatively using C, H, N and Sn elemental analysis as well as spectroscopic methods such as infrared (FTIR) and nuclear magnetic resonance (¹H, ¹³C, ¹H-¹³C HMQC and ¹¹⁹Sn NMR). In addition, complexes 1-4 obtained were screened for their cytotoxicity activity against HepG2 cells line. Results: Infrared spectroscopy showed that the coordination took place via oxygen atoms from the carboxylate anions. This indicated that the carboxylate anion acts as monodentate ligand in complexes 2 and 4. However, for distannoxane dimer (complexes 1 and 3), the carboxylate anions are found to exhibit monodentate and bidentate manner. In 119Sn NMR solution study, the tin atoms of complexes 1-3 were five-coordinated and four-coordinated in complex 4. From the ¹¹⁹Sn NMR, the tin atom of complex 2 was five-coordinated, this might be upon dilution, the crystal lattice were broken up resulting the carboxylate anions assembly self-arrangement. Hence, one of the carboxylate anions was located close to the tin atoms and exhibited bidentate chelation while the other carboxylate anion exhibited monodentate chelation in complex 2. Conclusion: Pure complexes 1-4 have been successfully obtained and complex 4 possessed promising biological screening activity compared to the parent acid and complexes 1-3.