Synthesis, characterization, theoretical study and biological activities of oxovanadium (IV) complexes with 2-thiophene carboxylic acid hydrazide

Oxovanadium (IV) complexes (1)–(3) have been synthesized by treating 2-thiophene carboxylic acid hydrazide with VOSO4⋅xH2O and VCl3(THF)3 in different M/L ratios. These complexes have been characterized by elemental analysis, UV–vis, FT-IR and mass spectrometry. The FT-IR data predicts the bidentate nature of the ligand which is also confirmed by semi-empirical study. Mass spectrometric data shows that molecular ion peak is only observed for 2-thiophene carboxylic acid hydrazide. The ESP map and thermodynamic parameters shows the presence of partial charge on atoms and stability of synthesized oxovanadium complexes, respectively. DNA binding study of complexes (1)–(3) was carried out by UV–vis and cyclic voltammetric methods which suggests the intercalative binding mode of the complexes with DNA. Cytotoxicity was checked by brine shrimp lethality assay and complex (1) showed greater cytotoxicity towards Artemia salina as compared to free ligand. Immuno-modulatory activity data shows that hydrazide ligand was more active as compared to oxovanadium complexes and standard drug. Complex (2) shows significant urease inhibition activity. The ligand and synthesized complexes were found inactive against all tested bacterial and fungal strains.