Role of metal Cu(II) and Ag(I) on molecular structure of 4-amino-N-(2, 6-dimethoxypyrimidin-4-yl) benzenesulfonamide in presence of 3-methyl pyridine: Synthesis, spectral, crystallographic and DNA interaction studies

Abstract

Mononuclear and dinuclear copper and silver complexes of bidentate sulfadimethoxine (sdmz), 4-Amino-N-(2,6-dimethoxypyrimidin-4-yl)benzenesulfonamide, ligand in presence of secondary ligand 3-methyl pyridine have been synthesized and characterized by X-ray diffraction and spectroscopic techniques. In crystal structure of mononuclear copper complex [{Cu(C12H12N4O4S).(C6H7N)}.(C6H7N)]; (complex 1), copper occupies special crystallographic position exhibiting a distorted octahedral geometry. A free solvent 3-methyl pyridine per asymmetric unit, completes the crystal structure of copper complex. Silver complex of bidentate sdmz ligand formulated as [Ag2(C12H12N4O4S)2(C6H7N)2]; (complex 2), crystallizes in centrosymmetric space group P21/c with two molecules per asymmetric unit. In the silver complex, silver located in a distorted tetrahedral coordination displaying argentophilic interactions with Ag-Ag separation distance of 2.8177(5) Å in molecule A and 2.8227(5) Å in molecule B. Secondary ligand plays a decisive role towards formulating coordination geometry as well as the molecular stability of both the complexes. Hirshfeld surface (HS) analysis reveals the quantitative contributions of different interactions on HS. Lipophilicity index (log P value) represents significant biological activity of the molecules, correlates well with the contribution of CH…π interaction. Both the complexes of sdmz ligand are screened for diverse biological activities to investigate the role of Cu(II) and Ag(I) metals on the molecular conformation of sdmz complexes. The interaction ability of both the metal complexes to DNA studied by absorption spectroscopy and viscosity measurement along with molecular docking study, conformed the intercalation mode of DNA binding with comparatively higher binding strength (Kb) for silver complex followed by copper complex and free sdmz ligand. The data of MIC against panel of gram positive and gram negative organisms confirm that both the metal complexes of sdmz possesses better inhibitory activities than that of sdmz ligand. Being less toxic, copper complex exhibits comparatively better response towards the panel of the gram positive and gram negative bacteria except B. subtilis. The observed differences in molecular structures and so on the biological activities of copper and silver complexes of sdmz-picoline ligand, point towards the impact of the respective metals.