Structure and vibrational frequencies of 1-naphthaldehyde based on density functional theory calculations
ABSTRACT The mid and far FTIR and Raman spectra were measured in the liquid state. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) and standard B3LYP/6-311+G** basis set combination. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical (SQM) force field. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Unambiguous vibrational assignment of all the fundamentals was made using the total energy distribution (TED).
SourceAvailable from: Chidan Kumar C. S.[Show abstract] [Hide abstract]
ABSTRACT: A novel (2E)-1-(5-chlorothiophen-2-yl)-3-(naphthalen-2-yl)prop-2-en-1-one [C17H11ClOS] compound has been synthesized and its structure has been characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the compound have been examined by means of the density functional theory, the Becke-3-Lee-Yang-Parr functional and the 6-311+G(3df,p) basis set. Reliable vibrational assignments and molecular orbitals have been investigated by the potential energy distribution and natural bonding orbital analyses, respectively. The compound crystallizes in the monoclinic space group P21/c with the unit cell parameters a = 5.7827(8) Å, b = 14.590(2) Å, c = 16.138(2) Å and Z = 4. The C=C bond of the central enone group adopts an E configuration. There is a good agreement between the theoretically predicted structural parameters and vibrational frequencies and those obtained experimentally.Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 11/2014; 132:174-182. DOI:10.1016/j.saa.2014.04.155 · 2.13 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: In this work, molecular geometries and fundamental vibrational frequencies of 2-furanacetic acid (2FAA) and its hydrogen bonded dimer were investigated using DFT/B3LYP method with 6-311++G(d,p) as basis set. The FT-infrared and FT-Raman spectra of the 2FAA compound were recorded in the region 4000-400cm(-1). The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. Complete vibrational assignments and analysis of the fundamental modes of monomer and dimer structures were performed on the basis of the potential energy distribution (PED) calculations. A study on the electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, are performed by time-dependent DFT (TD-DFT) approach. Molecular stability arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Topological parameters such an electron density and its Laplacian at bond critical points (BCP) of OH and O⋯H contact bonds were analyzed in details with the help of the atoms in molecules (AIM) approach in order to study the intermolecular hydrogen bonding. The nonlinear optical properties of the title molecule have been investigated. Moreover, molecular electrostatic potential (MEP) surface was plotted for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The nonlinear optical properties were reported and compared with that of the urea. The thermodynamic properties like heat capacity, entropy, and enthalpy have been calculated for the molecule at different temperatures. Copyright © 2014 Elsevier B.V. All rights reserved.Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2015; 136 Pt B:579-93. DOI:10.1016/j.saa.2014.09.071 · 2.13 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The Fourier-transform infrared and FT-Raman spectra of 1,5-Dimethyl Napthalene (15DMN) was recorded in the region 4000-400cm(-1) and 3500-50cm(-1) respectively. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 6M2C were carried out by density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The values of the total dipole moment (μ) and the first order hyperpolarizability (β) of the investigated compound were computed using B3LYP/6-311++G(d,p) calculations. The calculated results also show that 15DMN might have microscopic non-linear optical, MESP, NBO analysis with non-zero values. A detailed interpretation of infrared and Raman spectra of 15DMN is also reported. The calculated HOMO7-LUMO energy gap shows that charge transfer occur within the molecule. The molecular electrostatic potential map shows that the negative potential sites are on the electronegative atoms as well as the positive potential sites are around the hydrogen atoms.Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2014; 131. DOI:10.1016/j.saa.2014.04.019 · 2.13 Impact Factor