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

The oxidovanadium(IV) complex of composition [VO(acac)(SHA)] (where acac = [CH 3 COCHCOCH 3 − ]); (SHA = [2-OHC 6 H 4 C(O)NHO − ]) has been synthesized by the reaction of [VO(acac) 2 ] with salicylhydroxamic acid (SH 2 A) 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.