Molecular structure, nonlinear optical studies and spectroscopic analysis of chalcone derivative (2E)-3-[4-(methylsulfanyl) phenyl]1-(3-bromophenyl) prop-2-en-1-one by DFT calculations

A collective experimental and theoretical study was conducted on the molecular structure and vibrational spectra of nonlinear optical chalcone derivative (2E)-3-[4-(methylsulfanyl) pheny1]-1-(3bromophenyl) prop-2-en-1-one (3Br4MSP). The FT-IR and FT-Raman spectra of the molecule in the solid phase have been recorded. Density functional theory (DFT) calculations at B3LYP level with 6 311++G (d,p) basis set have been carried out to derive useful information about the molecular structure and to assign the relevant electronic and vibrational features. These calculations reveal that the optimized geometry closely resembles the experimental XRD data. The vibrational spectra were analyzed on the basis of the potential energy distribution (PED) of each vibrational mode, which allowed us to obtain a quantitative as well as qualitative interpretation of FT-IR and FT-Raman spectra. The UV vis spectrum was recorded in methanol solution. The excited state properties have been determined by TDDFT method and the effect of solvent was analyzed by PCM model. The most prominent transition corresponds to pi ->pi*. The reactivity parameters as chemical potential, global hardness, and electrophilicity index have also been calculated. To provide an explicit assignment and analysis of C-13 and H-1 NMR spectra, theoretical calculations on chemical shift of the title compound were done through GIAO method at B3LYP/6-311++G (d,p) level. The Mulliken's population analysis shows one of the simplest pictures of charge distribution. The standard statistical thermodynamic functions like heat capacity at constant pressure (C-p,m(0)), entropy (S-m(0)) and enthalpy (H-m(0)) were obtained from the theoretical harmonic frequencies for the optimized molecule. The nonlinear optical properties of title molecule are also addressed theoretically. Two contributions, vibrational and electronic, to the electrical properties polarizability and first order hyperpolarizability of 3Br4MSP have been evaluated using the self consistent field wave functions within the double harmonic oscillator approximation. (C) 2017 Elsevier B.V.All rights reserved.