title: Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin.
abstract: In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the σ* and π* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis.
authors.affiliation: Department of Physics (Science and Humanities), Sri Manakula Vinayagar Engg. College, Madagadipet, Puducherry 605 107, India. sebastian_astro@yahoo.com
authors.forename: S
authors.initials: S
authors.lastname: Sebastian
authors.forename: S
authors.initials: S
authors.lastname: Sylvestre
authors.forename: D
authors.initials: D
authors.lastname: Jayarajan
authors.forename: M
authors.initials: M
authors.lastname: Amalanathan
authors.forename: K
authors.initials: K
authors.lastname: Oudayakumar
authors.forename: T
authors.initials: T
authors.lastname: Gnanapoongothai
authors.forename: T
authors.initials: T
authors.lastname: Jayavarthanan
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D001424:Bacterial Infections / Q000188:drug therapy; D006801:Humans; D008958:Models, Molecular; D008968:Molecular Conformation; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014468:Umbelliferones / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D014468:Umbelliferones; C031477:7-hydroxycoumarin