Syntheses, structures, Hirshfeld surface analyses, BSA interactions and molecular docking studies of two leucine Schiff base complexes of oxovanadium(IV)

Two mixed-ligand oxovanadium(IV) complexes with a Schiff base derived from o-vanillin and leucine and 1,10-phenanthroline or 2,2 '-bipyridine as a co-ligand, [VO(o-van-Leu)phen] (1) and [VO(o-van-Leu)bipy]center dot H2O (2), were prepared and structurally characterized by IR spectra, elemental analyses and single-crystal X-ray diffraction. The crystal structures reveal that each oxovanadium(IV) atom in complexes 1 and 2 is surrounded by a N3O3 coordination sphere to form a distorted octahedron with a Schiff base and neutral bidentate ligand phen or bipy. Hirshfeld surface analyses and 2D fingerprint plots indicated that the molecular packings in crystals were dominated by H center dot center dot center dot H, O center dot center dot center dot H/H center dot center dot center dot O, C center dot center dot center dot H/H center dot center dot center dot C and p- p interactions. The interactions of both complexes with bovine serum albumin (BSA) were studied by using various spectroscopic and molecular docking methods. BSA binding constants (K), estimated by UV-Vis spectroscopy, were 2.53 x 10(4) M 1 for 1 and 3.18 x 104 M 1 for 2, respectively. Together with results of fluorescence and CD spectral studies, it showed that complex 2 has a better affinity for BSA than complex 1. Molecular docking investigation indicated that the two complexes had the similar mode of binding and located within subdomain IIA of BSA. Complex 2 had greater binding activity with the binding free energy (Delta G(binding)) of -6.5 kcal/mol than Complex 1 with Delta G(binding) of-5.42 kcal/mol, consisting with the analyses of spectroscopic experimental results.