Syntheses, crystal structures, antioxidant, in silico DNA and SARS-CoV-2 interaction studies of triorganotin(IV) carboxylates

Triorganotin(IV) carboxylate complexes R3SnL, where R = C4H9 (1), CH3 (2) and L = 2-chlorophenyl ethanoate, were synthesized and characterized by elemental analysis, FT-IR, NMR (H-1, C-13, Sn-119) and X-ray single crystal analysis. The solid state analyses confirmed a bridging bidentate coordination mode for the carboxylate ligand rendering the tin ion a penta-coordinated center in the synthesized complexes. NMR spectra revealed a change in the coordination number (5 -> 4) for tin when in the solution. The structural geometry and the electronic properties of complexes were calculated by using the density functional theory (DFT) method at B3LYP level 6-31G(d, p) and Lanl2DZ basis sets. A fairly good agreement was found between the observed and theoretical bond length and bond angle values for the complex (1) and (2). The in vitro antioxidant potential of the complexes was investigated by DPPH, ferrous ion chelation, ferric ion reducing, total antioxidant and hydroxyl free radical scavenging assays. The nature of the tin bonded R groups has apparently a significant impact on the antioxidant activity of the complexes. Molecular docking studies suggest intercalation as possible mode of complex-DNA interactions. Docking studies also confirm that interactions of the two complexes with some active site residues of SARS-CoV-2 nucleocapsid protein and angiotensin-converting enzyme 2 (ACE2) are probable. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Triorganotin(IV) carboxylate complexes were synthesized and characterized by various techniques, revealing different coordination numbers of the tin ion in solid state and solution, as well as the significant impact of the coordination mode on antioxidant activity. Molecular docking studies suggested possible interactions of the complexes with DNA and active sites of certain proteins.