Di- and tri-organotin(IV) carboxylates (1-47) of the type R2SnL2 [R = CH3, n-C4H9, n-C8H17] and R3SnL [R = CH3, n-C4H9, C6H5, where L= 3-(4-fluorophenyl)-2-methylacrylic acid (HL1), 2-(4-ethylbenzylidene) butanoic acid (HL2), 2-(4-ethoxybenzylidene) butanoic acid (HL3), 3-(4- cyanophenyl)-2-methylacrylic acid (HL4), 3-(4-ethoxyphenyl)-2-methylacrylic acid (HL5), 3-(2- fluorophenyl) 2-methylacrylic acid (HL6), 3-(4-fluorophenyl) acrylic acid (HL7), 3-(4- cyanophenyl) acrylic acid (HL8) have been synthesized and characterized by various analytical techniques such as elemental analysis, FT-IR, NMR (1H, 13C) and single crystal X-ray analysis. The results showed that the ligands coordinate with Sn atom via carboxylate moiety (COO−) with bidentate mode of binding. The diorganotin(IV) dicarboxylates exhibited distorted octahedral or skew trapezoidal geometry in solid state while the coordination number around tin changed from six to five in solution state. The triorganotin(IV) carboxylates exhibited polymeric trigonal bipyramidal geometry in solid state while monomeric tetrahedral geometry in solution state. The catalytic activity of the synthesized complexes was assessed in the production of biodiesel. Biodiesel is the monoalkyl ester of long chain fatty acids derived from the renewable feed stock, such as vegetable oil and is produced by a transesterification of vegetable oil with methanol. The results revealed that triorganotin(IV) complexes exhibited comparatively higher catalytic activity than their diorganotin(IV) analogues. The synthesized complexes were also screened for their biological activities such as antibacterial, antifungal and cytotoxicity. The results showed that triorganotin(IV) complexes exhibited more bactericidal, fungicidal and cytotoxic effects than diorganotin(IV) complexes. DNA interactions studies of the ligands and synthesized complexes were investigated by UV-Vis absorption spectroscopy. The results showed that both ligands and complexes interact with DNA via intercalation as well as minor groove binding.