title: Spectroscopic and quantum chemical electronic structure investigations of 3,4-dihydrocoumarin and 3-methylcoumarin.
abstract: A complete vibrational analysis of 3,4-dihydrocoumarin and 3-methylcoumarin have been performed according to SQM force field method based on ab initio and DFT calculation 6-311++G(d,p) basis set and their frequencies are compared. The influences of carbon-oxygen bond and methyl group to the vibrational frequencies of the title compounds have been discussed. The pronounced decrease of the lone pair orbital occupancy and the molecular stabilization energy show the hyperconjugation interaction from the NBO analysis. Calculations of molecular orbital geometry show that the visible absorption maxima of DHC and 3MC correspond to the electron transition between frontier orbitals such as translation from HOMO to LUMO. Gauge-including atomic orbital (GIAO) 1H and 13C chemical shift calculations have been calculated. Area of high, neutral and low electrostatic potential is determined for DHC and 3MC.
authors.affiliation: Department of Physics, A.A. Government Arts College, Pulivalam Road, Musiri 621 201, India. Electronic address: jjmarivu@yahoo.co.in.
authors.forename: M
authors.initials: M
authors.lastname: Arivazhagan
authors.affiliation: Department of Physics, Saranathan College of Engineering, Trichy 620 012, India.
authors.forename: R
authors.initials: R
authors.lastname: Kavitha
authors.affiliation: Department of Physics, Jeppiaar Engineering College, Chennai 600 119, India.
authors.forename: V P
authors.initials: VP
authors.lastname: Subhasini
mesh_terms: D000465:Algorithms; D002244:Carbon / Q000737:chemistry; D003374:Coumarins / Q000737:chemistry*; D004583:Electrons; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry; D012984:Software; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D014732:Vibration
chemical_list: D003374:Coumarins; D002244:Carbon; C030123:coumarin; C026308:3,4-dihydrocoumarin; D010100:Oxygen
keywords: 3MC; DHC; HOMO LUMO; NMR; Vibrational spectra