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Öğe Molecular structure and vibrational spectra of 7-Ethoxycoumarin by density functional method(ELSEVIER, 2013) Sarikaya, E. Karakas; Dereli, O.; Erdogdu, Y.; Gulluoglu, M. T.In the present study, as a result of detailed conformational search of the 7-Ethoxycoumarin, four different conformers of (7EC) have been obtained. The FT-IR and Raman spectra of 7EC were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Vibrational frequences of the title compound were calculated by B3LYP method using 6-311++G(d,p) basis sets. The calculated vibrational frequences were analyzed and compared with experimental results. Characteristic vibrational bands of the pyrone ring, methylene and CO groups have been identified. (c) 2013 Elsevier B.V. All rights reserved.Öğe Molecular structure and vibrational spectra of 7-Methoxy-4-mehylcoumarin by density functional method(ELSEVIER, 2013) Sarikaya, E. Karakas; Dereli, O.In the present study, as a result of detailed structural and conformational analysis of the 7-Methoxy-4-methylcoumarin, two different conformers have been obtained. The FT-IR and Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Vibrational frequences of the title compound were calculated by Becke3-Lee-Yang-Parr (B3LYP) functional using 6-311++G(d,p) basis sets. The ground state energies and dipole moments have also been computed. The calculated and scaled frequencies were compared with experimental values and on the basis of this comparison and total-energy distribution data assignments of fundamental vibrational modes were examined. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small. (C) 2013 Elsevier B.V. All rights reserved.Öğe Study on molecular structure and vibrational spectra of 5,7-dimethoxycoumarin using DFT: A combined experimental and quantum chemical approach(MAIK NAUKA/INTERPERIODICA/SPRINGER, 2014) Sarikaya, E. Karakas; Dereli, O.Conformational analysis of 5,7-Dimethoxycoumarin was performed and two stable conformers were obtained. The difference between the total energies of these conformers was 1.4698 kcal/mol and the difference between the zero point corrected energies was nearly zero. Vibrational frequencies of these conformers were calculated by B3LYP method using 6-311++G(d, p) basis sets and compared with experimentally recorded FT-IR and Raman spectra. Vibrational assignments were made by calculated total energy distributions. Time dependent density functional theory calculations were done by the same level of theory in order to investigate low-lying excited state and obtained results were compared with the maximum absorbtion peak value of experimental UV-visible spectrum.
