Potentially Antibacterial Mixed-Ligand Oxidovanadium(IV) Salicylhydroxamate Complex [VO(acac)SHA]: Synthesis, Characterization and Quantum Mechanical Study

Abstract

The oxidovanadium(IV) complex of composition [VO(acac)(SHA)] (where acac = [CH3COCHCOCH3−]); (SHA = [2-OHC6H4C(O)NHO−]) has been synthesized by the reaction of [VO(acac)2] with salicylhydroxamic acid (SH2A) in methanol + tetrahydrofuran and characterized by physicochemical and various spectral studies. The FTIR spectra indicated that salicylhydroxamate ion is bonded through carbonyl and hydroxamic oxygen (CONHO) atoms [O, O mode]. An optimized distorted square-pyramidal geometry around vanadium has been obtained by DFT/SIESTA using standard conjugate-gradient (CG) technique. From the HOMO–LUMO energy values, the molecular properties, viz. ionization potential (IP), electron affinity (EA), chemical potential (µ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω), have been calculated. The energy-resolved visualization of chemical bonding and molecular orbital contributions have been studied from the density of states, partial density of states and overall population density of states/crystal orbital overlap population and crystal orbital Hamiltonian population. The antibacterial activity of complex assayed against four bacterial strains, viz. E. coli, S. aureus, S. epidermidis and K. pneumoniae by MIC method, has shown it as promising growth-inhibiting agent.