Role of secondary ligand on Cd complex of sulfamethizole: synthesis, spectroscopic characterization, Hirshfeld surface analysis and DNA interaction

Abstract

Two isostructural Cd complexes, Cd-smtz-py (1) and Cd-smtz-pico (2) (smtz = sulfamethizole, py=pyridine and pico=picoline) are synthesized and characterized by single crystal X- ray diffraction technique. Both the isostructures (1) and (2) exhibit a distorted octahedral geometry coordinating to two thiadiazole and two aniline N atoms of four symmetry related sulfamethizole ligand in equatorial plane besides two secondary ligands pyridine in (1) / β-picoline in (2) situating at apical positions. In asymmetric unit of each structure, there are one molecule of free solvent: pyridine in (1) / β-picoline in (2). The IR and 1H NMR spectral data confirm the site of binding of the sulfamethizole ligand to the metal (Cd) which are in agreement with those established by X-ray data. Similarities and differences in these two isostructural complexes due to presence of different secondary ligand (pyridine in (1) and β-picoline in (2)) are explored by investigating quantitative contributions of intermolecular interactions both strong and weak to the molecular packing through Hirshfeld surface analysis, and 2D fingerprint plot. DNA binding interaction of Cd-smtz complex investigated using UV–Vis absorption and viscosity measurements. In vitro cytotoxicity screening of the complex and that of free ligand tested against brine shrimp. The antibacterial activity of Cd sulfamethizole and of free smtz ligand evaluated by micro broth dilution method.