IIJSRST184513 | Received : 01 March 2018 | Accepted : 07 March 2018 | March-April-2018 [ (4) 5 : 213-223] © 2018 IJSRST | Volume 4 | Issue 5 | Print ISSN: 2395-6011 | Online ISSN: 2395-602X Themed Section: Science and Technology 213 Synthesis, Crystal structure, Optical, Dielectric properties and Theoretical calculations of L-Phenylalanine Maleic Acid for Nonlinear Optical Applications K. Deepa 1 , S. Senthil 2 and J. Madhavan 1 * 1 Department of Physics, Loyola College, Chennai, Tamil Nadu, India 2 Department of Physics, Government Arts College for Men, Nandanam, Chennai, Tamil Nadu, India ABSTRACT Single crystals of L-phenylalanine maleic acid [LPM] with reasonable size have been grown by slow evaporation solution growth method. Quantum chemical calculation of L-phenylalanine maleic acid [LPM] was carried out by using DFT/B3LYP/6-31þG(d,p) method. The powder X-ray diffraction pattern was recorded and indexed. Both the experimental and theoretical vibrational spectrum validates the presence of functional groups. Polarizability, first order hyperpolarizability and the electric dipole moment values have been computed theoretically. TG/DTA analysis has been employed to understand the thermal and physio-chemical stability of the title compound. Frequency conversion property of the crystal was tested by Kurtz and Perry method. Dielectric constant and dielectric loss of picolinium maleate are measured in the frequency range from 50 Hz to 5 MHz at room temperature. Optical absorption behavior of the grown crystal was examined by recording the optical spectrum and band gap energy was also estimated. The calculated HOMO and LUMO energy shows the charge transfer nature of the molecule. Keywords. Powder XRD, optical absorption, Density Functional Theory, HOMO-LUMO analysis, FTIR, SHG efficiency. I. INTRODUCTION Photonics is playing an ever-increasing role in today’s technology by efficiently replacing electronics in electro optic devices. εulliken’s theory of charge transfer interactions between an electron donor and electron acceptor has been successfully applied to many interesting studies. These complexes have attracted great attention for nonlinear optical materials and electrical conductivities [1–5]. The bond between the donor and acceptor is formed by the interaction between the electron poor ring of the picric acid and electron rich ring of benzophenone. Picric acid also forms charge transfer complexes with pyridine, piperidine and amines [6-9]. The organic materials with benzophenone, which are of great applications for second and third order nonlinear optical properties due to their high nonlinearity with good electronic response. According to the concepts of the molecular and crystal technology, the organic molecules offer many possibilities to tailoring the substances with desired properties through optimization of the microscopic hyperpolarizabilities and the incorporation of the molecules in a crystalline lattice [10-12]. NLO properties of the crystals get affected due to the influence of hydrogen bonding on dipole alignment [13]. Among the available materials, nitro compounds receive much attraction because of its high NLO coefficients [14, 15]. 2-Methyl3, 5- dinitrobenzoicacid(MDNBA) is an aromatic compound has both electron donor group(carboxyl)and electro acceptor groups (methyl