Structure, spectroscopic study and DFT calculations of 2,6 bis (tri fluro methyl) benzoic acid (original) (raw)
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
The solid phase FTIR and FT-Raman spectra of 4-butyl benzoic acid (4-BBA) have been recorded in the regions 400-4000 and 50-4000 cm −1 , respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for monomer and dimer by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. 13 C and 1 H NMR spectra were recorded and 13 C and 1 H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded in the region 200-400 nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities, chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule.
Journal of Raman Spectroscopy, 2010
Vibrational spectral analysis was carried out for 4-methoxy-2-methyl benzoic acid (4M2MBA) by using Fourier transform infrared (FT-IR) (solid, gas phase) and FT-Raman spectroscopy in the range of 400-4000 and 10-3500 cm −1 respectively. The effects of molecular association through O-H· · ·O hydrogen bonding have been described by the single dimer structure. The theoretical computational density functional theory (DFT) and Hatree-Fock (HF) method were performed at 6-311++G(d,p) levels to derive the equilibrium geometry, vibrational wavenumbers, infrared intensities and Raman scattering activities. The scaled theoretical wavenumbers were also shown to be in good agreement with experimental data. The first-order hyperpolarizability (β 0 ) of this novel molecular system and related properties (β, α 0 and α) of 4M2MBA are calculated using the B3LYP/cc-pvdz basis set, based on the finite-field approach. A detailed interpretation of the infrared and Raman spectra of 4M2MBA is reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule were also constructed and compared with the experimental one.
Oriental Journal Of Chemistry, 2020
The molecular vibrations of 3-methoxy-2,4,5-trifluorobenzoic acid (MFBA) were studied by recording the FTIR and FT-Raman spectra and the vibrational frequencies have been compared with the DFT-B3LYP calculations. The optimized structural characteristics of the molecule have been studied by both calculated and experimental data. NBO analyses and the LUMO-HOMO energy gap of the molecule shows the intramolecular charge transfer interaction. Further, the nonlinear optical properties of MFBA have been investigated from the calculated values of first hyperpolarizability and total dipolemoment. The electrostatic potential and Mulliken charges of MFBA have also been performed.
Optics and Photonics Journal, 2015
The Fourier Transform Infrared (FTIR) and FT-Raman spectra of 4-methyl-3-nitrobenzoic acid have been recorded in the range 4000-400 cm −1 and 3500-50 cm −1 , respectively. The optimized geometry of the molecule, its vibrational frequencies along with corresponding intensities have been computed using the Density Functional Theory (DFT) employing B3LYP/6-311++G basis set. The scaled values of harmonic vibrational frequencies obtained in the computations have been compared with their experimental counter parts. The scaling factors have been refined to reproduce the frequencies with an RMS error of 11.68 cm −1 between the experimental and computed frequencies. The theoretically constructed spectra agree satisfactorily with those of experimental spectra. First order hyperpolarizability constants have also been evaluated.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
The (E)-2-(2-hydroxybenzylideneamino)-3-methylbutanoic acid (E)-2HBAMBA was synthesized. The FT-IR, FT-Raman and UV-vis spectra have been recorded and characterized. Theoretical wavenumbers along with IR and Raman intensities were calculated using B3LYP/6-31G(d,p) level and total energy distribution (TED) of the various normal mode of vibrations were also studied. The conformational analysis was performed for a stable conformer by selecting the dihedral angles and the optimized bond parameters were calculated for the stable structure. Effect of intramolecular interactions is calculated by changing the orientation of hydroxyl hydrogen. To know the charge transfer while changing the hydroxyl group hydrogen orientation, the NBO analysis was performed. Using the same level of calculation, the electronic charge transfers were calculated and compared.
2011
The Fourier transform infrared (FT-IR) and FT Raman spectra of 5-amino-2-hydroxybenzoic acid (5A2HBA) have been recorded in the regions 400 0–4 0 and 4000–100 cm , respectively. 5-amino-2-hydroxybenzoic acid is used as an anti-in flammatory agent .The optimized geometry, frequency and intensity of the vibrational bands of (5A2HBA) were obtained by ab initio and DFT levels of theory with complete relaxation in th e potential energy surface using 6-31G(d,p) basis set. A complete vibrational assignment aided by the theoretical harmonic frequency analysis has been proposed. The harmonic vibrationa l frequencies, infrared intensities and Raman scattering activities, force constants are ca lcul ted by ab initio HF and DFT B3LYP methods with 6-31G(d,p) basis set. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyz ed using natural bond orbital (NBO) analysis. The results show that charge in electron de sity (ED) in the σ* and π* anti...
2016
Extensive quantum chemical calculations of energy, geometrical structure, harmonic vibrational frequencies and the construction of theoretical spectrograms of IR and Raman spectra of the molecule, methyl 2,4-dihydroxy-6-methyl benzoate(methyl orsellinate) have been carried out by Hartree-Fock (HF) and Density Functional Theory (DFT/B3LYP) method with 6311++G(d, p) basis set. The assignments of normal modes of the vibration of the title molecule along with the observed frequencies (FT-IR and FTR) and scaled frequencies have been obtained by HF/DFT computation. The simulated NMR spectra are obtained by (GIAO) gauge independent atomic orbital method and their chemical shifts are compared with the experimental 13 C NMR and 1 H NMR spectra. Molecular geometric parameters, dipole moment, mullikan charge, thermodynamic properties, FMO analysis and NLO properties have also been computed and discussed in a detailed manner.The electrostatic potential surface and the mullikan charge analysis i...
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010
Theoretical calculations on the molecular geometry and the vibrational spectrum of 4-hydroxybenzoic acid were carried out by the Density Functional Theory (DFT/B3LYP) method. In addition, IR and Raman spectra of the 4-hydroxybenzoic acid in solid phase were newly recorded using them in conjunction the experimental and theoretical data (including SQM calculations), a vibrational analysis of this molecular specie was accomplished and a reassignment of the normal modes corresponding to some spectral bands was proposed. The geometries of monomers and dimers in gas phase were optimized using the DFT B3LYP method with the 6-31G*, D95** and 6-311++G** basis sets. Also, both the vibrational spectra recorded and the results of the theoretical calculations show the presence of one stable conformer for the 4hydroxybenzoic acid cyclic dimer. The B3LYP/6-31G* method was used to study the structure for cyclic dimer of 4-hydroxybenzoic acid and for a complete assignment our results were compared with results of the cyclic dimer of benzoic acid. A scaled quantum mechanical analysis was carried out to yield the best set of harmonic force constants. The formation of the hydrogen bond was investigated in terms of the charge density by the AIM program and by the NBO calculations.