Vibrational spectra and non linear optical proprieties of l-histidine oxalate: DFT studies

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 79; no. 3; pp. 554 - 561
• Main Authors: Ahmed, A. Ben, Elleuch, N., Feki, H., Abid, Y., Minot, C.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.08.2011
• Subjects: Crystal structure; Crystallography, X-Ray; DFT; Histidine - analogs & derivatives; Histidine - chemistry; Hydrogen Bonding; Hyperpolarizability; Models, Molecular; Molecular Structure; Oxalates - chemistry; Quantum Theory; Raman; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; TD-DFT; IR; Raman; DFT; Hyperpolarizability; Crystal structure; TD-DFT
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2011.03.033

. In acid-base hybrid crystals, hydrogen bonds play an important role not only in the creation of crystal structure and its stability, but also in the enhancement of the polarizability α and the hyperpolarizability β of the crystal due to the perturbation of the electronic structure of l-histidine and also due to the strong electron–phonon coupling. [Display omitted] ► In this study, l-histidine oxalate crystallizes in the space group P2 12 12 1 of orthorhombic system. ► All the experimental vibrational bands have been discussed and assigned to normal mode. ► The non linear optical properties of l-histidine oxalate have been investigated by DFT method. ► The results indicate hydrogen bonding increased the hyperpolarizability of the crystal. This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a nonlinear optical material l-histidine oxalate. Due to the lack of sufficiently precise information on geometric structure in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of l-histidine oxalate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2 12 12 1 of orthorhombic system. The FT-IR and Raman spectra of l-histidine oxalate were recorded and analyzed. The vibrational wave numbers were examined theoretical with the aid of Gaussian98 package of programs using the DFT//B3LYP/6-31G(d) level of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied compound. The geometrical parameters of the title compound are in agreement with the values of similar structures. To investigate microscopic second order non-linear optical NLO behaviour of the examined complex, the electric dipole μ tot, the polarizability α tot and the hyperpolarizability β tot were computed using DFT//B3LYP/6-31G(d) method. According to our calculation, the title compound exhibits non-zero β tot value revealing microscopic second order NLO behaviour.