Biological screening, DNA interaction studies, and catalytic activity of organotin(IV) 2-(4-ethylbenzylidene) butanoic acid derivatives: synthesis, spectroscopic characterization, and X-ray structure

<div><p>A series of organotin(IV) carboxylates, [Me₂SnL₂] (<b>1</b>), [Bu₂SnL₂] (<b>2</b>), [Oct₂SnL₂] (<b>3</b>), [Me₃SnL] (<b>4</b>), and [Ph₃SnL] (<b>5</b>), where L = 2-(4-ethylbenzylidene) butanoic acid, have been synthesized and characterized by elemental analysis, FT-IR, and NMR (¹H, ¹³C, and ¹¹⁹Sn). [Me₃SnL] (<b>4</b>) was analyzed by single crystal X-ray analysis which showed polymeric structure with distorted trigonal bipyramidal geometry. The complexes were screened for biological activities including antibacterial, antifungal, and cytotoxic activities. UV–vis absorption studies of <b>HL</b>, <b>1</b> and <b>4</b> with SS-DNA revealed groove binding as well as intercalation, which may be due to the presence of planar phenyl groups that facilitate interaction with DNA. The determined intrinsic binding constants, 6.04 × 10³ M⁻¹ (<b>HL</b>), 9.6 × 10³ M⁻¹ (<b>1</b>), and 1.7 × 10⁴ M⁻¹ (<b>4</b>), showed that <b>HL</b> and <b>1</b> have less binding strength than <b>4</b>. The catalytic activities of di- and tri-organotin(IV) complexes were assessed in transesterification of triglycerides (linseed oil) into fatty acid methyl esters (biodiesel). The tri-organotin(IV) complexes have better catalytic activity than their di-analogs.</p></div