title: Vibrational spectral studies and non-linear optical properties of L-leucine L-leucinium picrate: a Density Functional Theory approach.
abstract: Single crystals of l-leucine l-leucinium picrate were grown by slow evaporation at room temperature and were characterized by X-ray powder diffraction study to confirm the crystalline nature of the synthesized compound. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the Density Functional Theory (DFT) method using the B3LYP function with the 6-31G(d) basis set. Good consistency is found between the calculated results and the experimental structure, IR, and Raman spectra. The detailed interpretation of the vibrational modes was carried out. The natural bond orbital (NBO) analysis, confirms the occurrence of intermolecular hydrogen bonds that are responsible for the stabilization of the title compound, leading to high nonlinear optical (NLO) activity. The lowering in the HOMO and LUMO energy gap explains the eventual charge transfer interactions that take place within the molecules.
authors.affiliation: Laboratoire de Physique Appliquée (LPA), Université de Sfax, Faculté des Sciences, BP 1171, 3000 Sfax, Tunisia. sameh_guidara@yahoo.fr
authors.forename: Sameh
authors.initials: S
authors.lastname: Guidara
authors.forename: Habib
authors.initials: H
authors.lastname: Feki
authors.forename: Younes
authors.initials: Y
authors.lastname: Abid
mesh_terms: D000838:Anions; D003460:Crystallization; D004560:Electricity; D006860:Hydrogen Bonding; D007930:Leucine / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D017711:Nonlinear Dynamics; D055620:Optical Phenomena; D010851:Picrates / Q000737:chemistry*; D011208:Powders; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration; D014961:X-Ray Diffraction
chemical_list: D000838:Anions; C586935:L-leucine-L-leucinium picrate; D010851:Picrates; D011208:Powders; C005858:picric acid; D007930:Leucine
keywords: DFT; First hyperpolarizability; NBO; Vibrational spectroscopy; l-leucine l-leucinium picrate