Experimental and theoretical studies on new organotin(IV) complexes with oxygen donor ligand: DNA binding, molecular docking and antimicrobial activity

In the present paper, oxygen donor ligand having carboxylate moiety and two new tri-organotin(IV) carboxylates, (Ph₃Sn)₂L (1) and (n-Bu₃Sn)₂L (2) were prepared successfully and characterized by FT-IR, NMR and UV-visible spectroscopic analysis. FT-IR results for complexes (1) and (2) with ∆ν values 216 and 188 cm^-1 indicated bidentate binding mode of ligand leading to trigonal bipyramidal geometry. NMR spectral results of ligand and complexes were compared and complex formation was confirmed by disappearance of carboxylic acidic proton in the range 13.14-13.10 ppm. DFT studies were performed for comparative spectroscopic studies i.e., FT-IR, UV-Vis and to reveal the structural geometrical parameters of ligand and complexes which showed an outstanding collaboration between the DFT-based results and attained experimental results. The antimicrobial potential of newly synthesized ligand and complexes were evaluated and results exhibited significant potential by these compounds. The antibacterial molecular docking results revealed that complex (Ph₃Sn)₂L (1) has excellent binding capability with the target protein (2EX9) and the complex (n-Bu₃Sn)₂L (2) has the least binding with protein. The antifungal docking results revealed that metal presence enhances the anti-fungal activity of the compounds and the results are in good agreement with experimental results. The DNA binding results revealed that organotin(IV) complexes interact with DNA better than ligand via an intercalative mode of interaction as indicated by hypochromism.

Graphical abstract

We report DFT and Molecular Docking-based computational studies of HL¹, Complex (1), and Complex (2). Consequently, an outstanding collaboration between the DFT-based results and experimental results was attained. These compounds have shown anti-tumor potential as indicated by binding constant values of 1.087 x 10⁵ M^-1, 2.73 x 10⁴ M^-1, and 1.26 x 10² M^-1 for ligand HL¹, complex (1) and (2) respectively, and hypochromic effect indicate intercalative mode of binding interaction.