title: Molecular structure, vibrational spectra, NBO, UV and first order hyperpolarizability, analysis of 4-Chloro-dl-phenylalanine by density functional theory.
abstract: The Fourier transform infrared (4000-400cm(-1)) and Fourier transform Raman (3500-50cm(-1)) spectra of 4-Chloro-dl-phenylalanine (4CLPA) were recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational wavenumbers were investigated with the help of density functional theory (DFT) method using B3LYP/6-31G(d,p) as basis set. The observed vibrational wavenumbers were compared with the calculated results. Natural bond orbital analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction. Predicted electronic absorption spectra from TD-DFT calculation have been analyzed comparing with the UV-Vis (200-800nm) spectrum. The effects of chlorine and ethylene group substituent in benzene ring in the vibrational wavenumbers have been analyzed. The HOMO-LUMO energy gap explains the charge interaction taking place within the molecule. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of 4CLPA were calculated. The Chemical reactivity and chemical potential of 4CLPA is calculated. In addition, molecular electrostatic potential (MEP), frontier molecular orbital (FMO) analysis were investigated using theoretical calculations.
authors.affiliation: Department of Physics (Engg.), Annamalai University, Annamalainagar 608 002, India.
authors.forename: K
authors.initials: K
authors.lastname: Govindarasu
authors.affiliation: Department of Physics (Engg.), Annamalai University, Annamalainagar 608 002, India. Electronic address: eswarankavitha@gmail.com.
authors.forename: E
authors.initials: E
authors.lastname: Kavitha
mesh_terms: D054879:Halogenation; D008958:Models, Molecular; D010649:Phenylalanine / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D010649:Phenylalanine
keywords: 4-Chloro-dl-phenylalanine; Hyperpolarizability; MEP; NBO; TD-DFT; UV–Vis