title: Vibrational and electronic spectroscopic studies of melatonin.
abstract: We report the infrared absorption and Raman spectra of melatonin recorded with 488 and 632.8 nm excitations in 3600-2700 and 1700-70 cm(-1) regions. Further, we optimized molecular structure of the three conformers of melatonin within density functional theory calculations. Vibrational frequencies of all three conformers have also been calculated. Observed vibrational bands have been assigned to different vibrational motions of the molecules on the basis of potential energy distribution calculations and calculated vibrational frequencies. Observed band positions match well with the calculated values after scaling except NH stretching mode frequencies. It is found that the observed and calculated frequencies mismatch of NH stretching is due to intermolecular interactions between melatonin molecules.
authors.affiliation: Department of Physics, Panjab University, Chandigarh 160 014, India.
authors.forename: Gurpreet
authors.initials: G
authors.lastname: Singh
authors.forename: J M
authors.initials: JM
authors.lastname: Abbas
authors.forename: Sukh Dev
authors.initials: SD
authors.lastname: Dogra
authors.forename: Ritika
authors.initials: R
authors.lastname: Sachdeva
authors.forename: Bimal
authors.initials: B
authors.lastname: Rai
authors.forename: S K
authors.initials: SK
authors.lastname: Tripathi
authors.forename: Satya
authors.initials: S
authors.lastname: Prakash
authors.forename: Vasant
authors.initials: V
authors.lastname: Sathe
authors.forename: G S S
authors.initials: GS
authors.lastname: Saini
mesh_terms: D004583:Electrons; D008550:Melatonin / Q000737:chemistry*; D008968:Molecular Conformation; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D008550:Melatonin
keywords: Density functional theory calculations; Infrared spectra; Melatonin; Raman spectra