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Swaminathan J, Ramalingam M, Sundaraganesan N. Molecular structure and vibrational spectra of 3-amino-5-hydroxypyrazole by density functional method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2009; 71:1776-1782. [PMID: 18760957 DOI: 10.1016/j.saa.2008.06.044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/06/2008] [Accepted: 06/25/2008] [Indexed: 05/26/2023]
Abstract
In this work, we report a combined experimental and theoretical study on molecular and vibrational structure of 3-amino-5-hydroxypyrazole (3A5HP). The Fourier transform infrared and Fourier transform Raman spectra of 3A5HP were recorded in the solid phase. The molecular geometry and vibrational frequencies of 3A5HP in the ground state have been calculated by using the density functional method B3LYP with basis sets, 6-311++G(d,p), 6-311+G(3df,2p), 6-311+G(3df,2pd), CC-pVDZ, aug-CC-pVDZ and CC-pVTZ. The optimized geometrical parameters obtained by B3LYP show best agreement with the experimental values. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.
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77
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Ramalingam M, Jaccob M, Swaminathan J, Venuvanalingam P, Sundaraganesan N. Harmonic analysis of vibrations of morpholine-4-ylmethylthiourea: a DFT, midinfrared and Raman spectral study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 71:996-1002. [PMID: 18602861 DOI: 10.1016/j.saa.2008.02.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 02/06/2008] [Accepted: 02/13/2008] [Indexed: 05/26/2023]
Abstract
The FTIR and FT-Raman spectra of morpholine-4-ylmethylthiourea (MMTU) were recorded in the region of mid-IR (400-4,000 cm(-1)). Initial geometry generated from the standard geometrical parameters was relaxed without any constraint on the potential energy surface at MP2 and DFT levels adopting the standard 6-31++G and 6-311+G basis set. With the help of two specific scaling procedures the computed harmonic frequencies have been compared with the observed vibrational wave numbers of FTIR and FT-Raman spectra and assigned to different normal modes of the molecule. Most of the vibrational modes have wave numbers in the expected range. The appropriate theoretical spectrograms of the IR spectra of MMTU have been also constructed.
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Sundaraganesan N, Meganathan C, Joshua BD, Mani P, Jayaprakash A. Molecular structure and vibrational spectra of 3-chloro-4-fluoro benzonitrile by ab initio HF and density functional method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 71:1134-1139. [PMID: 18448383 DOI: 10.1016/j.saa.2008.03.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 02/23/2008] [Accepted: 03/11/2008] [Indexed: 05/26/2023]
Abstract
In this work, the experimental and theoretical spectra of 3-chloro-4-fluoro benzonitrile (3C4FBN) were studied. The Fourier transform infrared and Fourier transform Raman spectra of 3C4FBN were recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-311++G(d,p) basis set. The harmonic-vibrational frequencies, infrared intensities and Raman scattering activities of the title compound were performed at and HF/B3LYP/6-311++G(d,p) level of theories. The scaled theoretical wave number showed very good agreement with the experimental values. The thermodynamic functions of the title compound was also performed at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) level of theories. A detailed interpretation of the infrared and Raman spectra of 3C4FBN was reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.
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Sundaraganesan N, Kalaichelvan S, Meganathan C, Joshua BD, Cornard J. FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 4-N,N'-dimethylamino pyridine. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 71:898-906. [PMID: 18358770 DOI: 10.1016/j.saa.2008.02.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 01/31/2008] [Accepted: 02/05/2008] [Indexed: 05/26/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-N,N'-dimethylamino pyridine (4NN'DMAP). The Fourier transform infrared and Fourier transform Raman spectra of 4NN'DMAP was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-31G(d,p) and 6-311++G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the title compound were performed at same level of theories. The scaled theoretical wavenumber showed very good agreement with the experimental values. The thermodynamic functions of the title compound was also performed at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) level of theories. A detailed interpretation of the infrared and Raman spectra of 4NN'DMAP was reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.
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Ramalingam M, Sundaraganesan N, Saleem H, Swaminathan J. Experimental (FTIR and FT-Raman) and ab initio and DFT study of vibrational frequencies of 5-amino-2-nitrobenzoic acid. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 71:23-30. [PMID: 18178128 DOI: 10.1016/j.saa.2007.11.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 11/06/2007] [Accepted: 11/15/2007] [Indexed: 05/25/2023]
Abstract
The FTIR and FT-Raman spectra of 5-amino-2-nitrobenzoic acid (ANB) have been recorded in the region 400-4000 cm(-1). The observed frequencies were assigned to different modes of vibrations on the basis of fundamental, combination and overtones. The geometry has been optimized with complete relaxation on the potential energy surface at HF, MP2 and B3LYP level of theories using 6-311++G(d,p) basis set and compared with the crystal data. The possible hydrogen bond interaction has been estimated taking a model compound. Further harmonic vibrational frequency calculations have been carried out at HF and B3LYP levels and the scaled values were in good agreement with majority of the experimental observations. The theoretically constructed spectra coincide satisfactorily with those of experimental spectra.
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81
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Mani P, Umamaheswari H, Dominic Joshua B, Sundaraganesan N. Molecular structure, vibrational spectra and NBO analysis of phenylisothiocyanate by density functional method. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2008.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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82
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Sundaraganesan N, Meganathan C, Karthikeyan B. FT-IR, FT-Raman spectra and quantum chemical calculations of some chloro substituted phenoxy acetic acids. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:430-438. [PMID: 18282793 DOI: 10.1016/j.saa.2007.12.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 12/12/2007] [Accepted: 12/15/2007] [Indexed: 05/25/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of o-chlorophenoxy acetic acid (OCPAA) and p-chlorophenoxy acetic acids (PCPAA). The FT-IR and Fourier transform-Raman spectra of both the compounds was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-311++G(d,p) basis set and harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-311++G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compounds were also performed at B3LYP/6-311++G(d,p) level of theory. A detailed interpretation of the infrared and Raman spectra of o-chloro and p-chlorophenoxy acetic acid is reported. The theoretical FT-IR spectrograms for the title molecules have been constructed.
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83
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Sundaraganesan N, Dominic Joshua B, Meganathan C, Meenashi R, Cornard JP. Vibrational spectra and quantum chemical calculations of 3,4-diaminobenzoic acid. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:376-383. [PMID: 18160339 DOI: 10.1016/j.saa.2007.10.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 10/29/2007] [Indexed: 05/25/2023]
Abstract
The Fourier Transform Raman and Fourier Transform infrared spectra of 3,4-diaminobenzoic acid (3,4-DABA) were recorded in the solid phase. Geometry optimizations were done without any constraint and harmonic-vibrational wave numbers and several thermodynamic parameters were calculated for the minimum energy conformer at ab initio and DFT levels invoking 6-311++G(d,p) basis set. The results were compared with the experimental values with the help of specific scaling procedures, the observed vibrational wavenumbers in FT-IR and FT-Raman spectra were analyzed and assigned to different normal modes of the molecule. Most of the modes have wavenumbers in the expected range, the error obtained was in general very low. The appropriate theoretical spectrograms for the IR and Raman spectra of the title molecule were also constructed.
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84
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Sundaraganesan N, Priya M, Meganathan C, Joshua BD, Cornard JP. FT-IR, FT-Raman spectra and quantum chemical calculations of 3,4-dimethoxyaniline. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:50-9. [PMID: 17765601 DOI: 10.1016/j.saa.2007.07.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 07/07/2007] [Accepted: 07/11/2007] [Indexed: 05/17/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 3,4-dimethoxyaniline (3,4-DMA). The Fourier transform infrared and Fourier transform Raman spectra of 3,4-DMA was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods using 6-31G(d,p) and 6-311++G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities, Raman scattering activities and the thermodynamic functions of the title compound were performed at and HF/B3LYP/6-311++G(d,p) level of theories. The scaled theoretical wavenumber showed very good agreement with the experimental values. A detailed interpretation of the infrared and Raman spectra of 3,4-DMA was reported. The theoretical spectrograms for IR and Raman spectra of the title molecule have been constructed.
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85
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Sundaraganesan N, Umamaheswari H, Meganathan C, Sebastian S. Molecular structure and vibrational spectra of 4-nitrobenzylchloride by ab initioHartree–Fock and density functional methods. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802036013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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86
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Subramanian M, Anbarasan P, Ilangovan V, Sundaraganesan N. FT-IR, FT-Raman spectra and DFT vibrational analysis of 2-aminobiphenyl. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020701829856] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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87
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Sundaraganesan N, Anand B, Meganathan C, Joshua BD. FT-IR, FT-Raman spectra and ab initio HF, DFT vibrational analysis of p-chlorobenzoic acid. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 69:871-9. [PMID: 17658292 DOI: 10.1016/j.saa.2007.05.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2006] [Accepted: 05/18/2007] [Indexed: 05/16/2023]
Abstract
The infrared, the Fourier transform infrared and Fourier transform Raman spectra of p-chlorobenzoic acid (p-CBA) has been recorded in the region 4000-600 cm(-1), 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of p-CBA were obtained by the ab initio HF and DFT (B3LYP) methods with complete relaxation in the potential energy surface using 6-311+G(d,p) basis set. The harmonic-vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.
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88
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Sundaraganesan N, Anand B, Meganathan C, Joshua BD, Saleem H. Vibrational spectra and assignments of 3-aminobenzyl alcohol by ab initio Hartree-Fock and density functional method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 69:198-204. [PMID: 17512242 DOI: 10.1016/j.saa.2007.03.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 03/18/2007] [Accepted: 03/19/2007] [Indexed: 05/15/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 3-aminobenzyl alcohol. The FT-Raman and FT-IR spectra of 3-aminobenzyl alcohol were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities, Raman scattering activities, depolarization ratios and reduced masses were calculated by ab initio HF and density functional B3LYP method with 6-311+G(d,p) basis sets. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory. A detailed interpretation of the infrared and Raman spectra of 3-aminobenzyl alcohol is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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89
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Sundaraganesan N, Meganathan C, Saleem H, Joshua BD. Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 5-amino-o-cresol. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 68:619-25. [PMID: 17324615 DOI: 10.1016/j.saa.2006.12.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2006] [Revised: 12/03/2006] [Accepted: 12/16/2006] [Indexed: 05/14/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of 5-amino-o-cresol (5AOC) were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by HF and density functional B3LYP method with the 6-311G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-311G(d,p) and B3LYP/6-311G(d,p) levels of theory. A detailed interpretation of the infrared and Raman spectra of 5-amino-o-cresol is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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90
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Sundaraganesan N, Ilakiamani S, Dominic Joshua B. Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 3,4-dimethylbenzaldehyde. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 68:680-7. [PMID: 17418627 DOI: 10.1016/j.saa.2006.12.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 12/19/2006] [Accepted: 12/25/2006] [Indexed: 05/14/2023]
Abstract
The FT-IR and FT-Raman spectra of 3,4-dimethylbenzaldehyde (3,4-DMB) has been recorded in the region 4000-400 and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of 3,4-DMB were obtained by the ab initio and DFT levels of theory with complete relaxation in the potential energy surface using 6-311G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.
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91
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Sundaraganesan N, Anand B, Meganathan C, Joshua BD. FT-IR, FT-Raman spectra and ab initio HF, DFT vibrational analysis of 2,3-difluoro phenol. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 68:561-6. [PMID: 17324616 DOI: 10.1016/j.saa.2006.12.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Revised: 12/12/2006] [Accepted: 12/16/2006] [Indexed: 05/14/2023]
Abstract
The FT-IR and FT-Raman spectra of 2,3-difluoro phenol (2,3-DFP) has been recorded in the region 4000-400 and 4000-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of 2,3-DFP were obtained by the ab initio HF and density functional theory (DFT) levels of theory with complete relaxation in the potential energy surface using 6-311+G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.
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92
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Sundaraganesan N, Joshua BD. Vibrational spectra and fundamental structural assignments from HF and DFT calculations of methyl benzoate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 68:771-7. [PMID: 17433769 DOI: 10.1016/j.saa.2006.12.059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 12/20/2006] [Accepted: 12/25/2006] [Indexed: 05/14/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of methyl benzoate (MB) were recorded in the liquid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, depolarization ratios, reduced masses were calculated by Hartree-Fock (HF) and density functional B3LYP method with the 6-311+G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory. A detailed interpretations of the infrared and Raman spectra of methyl benzoate is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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93
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Sundaraganesan N, Meganathan C, Anand B, Joshua BD, Lapouge C. Vibrational spectra and assignments of 2-amino-5-iodopyridine by ab initio Hartree-Fock and density functional methods. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:830-6. [PMID: 17018261 DOI: 10.1016/j.saa.2006.08.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2006] [Accepted: 08/31/2006] [Indexed: 05/12/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of 2-amino-5-iodopyridine were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by HF and DFT (B3LYP) methods with the 6-31G(d,p) basis set for C, N, H and LANL2DZ pseudopotential for I. The scaled theoretical wavenumbers showed very good agreement with the experimental ones. A detailed interpretation of the infrared and Raman spectra of 2-amino-5-iodopyridine is reported on the basis of the calculated potential energy distribution. The theoretical spectrograms for the IR spectrum of the title molecule have been constructed.
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94
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Sundaraganesan N, Ilakiamani S, Subramani P, Joshua BD. Comparison of experimental and ab initio HF and DFT vibrational spectra of benzimidazole. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:628-35. [PMID: 16979935 DOI: 10.1016/j.saa.2006.08.020] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2006] [Revised: 08/15/2006] [Accepted: 08/15/2006] [Indexed: 05/11/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of benzimidazole. The laser Raman and Fourier transform infrared spectra of benzimidazole were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities, Raman scattering activities, depolarization ratios and reduced masses were calculated by HF and density functional B3LYP method with the 6-311G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-31G(d,p)/6-311G(d,p) and B3LYP/6-31G(d,p)/6-311G(d,p) levels of theory. A detailed interpretations of the infrared and Raman spectra of benzimidazole is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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95
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Sundaraganesan N, Ilakiamani S, Dominic Joshua B. FT-Raman and FT-IR spectra, ab initio and density functional studies of 2-amino-4,5-difluorobenzoic acid. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:287-97. [PMID: 16919499 DOI: 10.1016/j.saa.2006.07.016] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2006] [Revised: 07/06/2006] [Accepted: 07/08/2006] [Indexed: 05/11/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of 2-amino-4,5-difluorobenzoic acid (2A45DFBA) were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, depolarization ratios were calculated by HF and density functional B3LYP method with the 6-31+G(d, p) and 6-311+G(d, p) basis sets. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-31+G(d, p)/6-311+G(d, p) and B3LYP/6-31+G(d, p)/6-311+G(d, p) levels of theory. A detailed interpretations of the infrared and Raman spectra of 2-amino-4,5-difluorobenzoic acid is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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96
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Sundaraganesan N, Anand B, Joshua BD. Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 2-amino-5-methylphenol. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:550-8. [PMID: 16996297 DOI: 10.1016/j.saa.2006.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 08/09/2006] [Accepted: 08/14/2006] [Indexed: 05/11/2023]
Abstract
The laser Raman and Fourier transform infrared spectra of 2-amino-5-methylphenol were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities, Raman scattering activities, depolarization ratios and reduced masses were calculated by HF and density functional B3LYP methods by using 6-311+G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-31G(d,p)/6-311+G(d,p) and B3LYP/6-31G(d,p)/6-311+G(d,p) levels of theory. A detailed interpretations of the infrared and Raman spectra of 2-amino-5-methylphenol is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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97
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Sundaraganesan N, Illakiamani S, Meganathan C, Joshua BD. Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 3-aminobenzotrifluoride. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:214-24. [PMID: 16945578 DOI: 10.1016/j.saa.2006.07.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2006] [Accepted: 07/03/2006] [Indexed: 05/11/2023]
Abstract
In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 3-aminobenzotrifluoride. The FT-Raman and Fourier transform infrared spectra of 3-aminobenzotrifluoride (3ABTF) were recorded in the liquid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, depolarization ratios, reduced masses were calculated by HF and density functional B3LYP method with the 6-31G(d,p) and 6-311G(d,p) basis sets. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-31G(d,p)/6-311G(d,p) and B3LYP/6-31G(d,p)/6-311G(d,p) levels of theory. A detailed interpretations of the infrared and Raman spectra of 3ABTF is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.
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Sundaraganesan N, Meganathan C, Anand B, Lapouge C. FT-IR, FT-Raman spectra and ab initio DFT vibrational analysis of p-bromophenoxyacetic acid. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 66:773-80. [PMID: 16870498 DOI: 10.1016/j.saa.2006.04.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/23/2006] [Accepted: 04/25/2006] [Indexed: 05/11/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of p-bromophenoxyacetic acid were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by HF and DFT (B3LYP) method with the 6-31G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental ones. A detailed interpretation of the infrared and Raman spectra of p-bromophenoxyacetic acid is reported on the basis of the calculated potential energy distribution. The theoretical spectrograms for the IR spectrum of the title molecule have been constructed.
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99
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Sundaraganesan N, Joshua BD, Settu K. Vibrational spectra and assignments of 5-amino-2-chlorobenzoic acid by ab initio Hartree-Fock and density functional methods. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 66:381-8. [PMID: 16843714 DOI: 10.1016/j.saa.2006.03.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Accepted: 03/03/2006] [Indexed: 05/10/2023]
Abstract
The Fourier transform Raman and Fourier transform infrared spectra of 5-amino-2-chlorobenzoic acid (5A2CBA) were recorded in the solid phase. Geometry opitimizations were done without any constraint and harmonic-vibrational wavenumber and several thermodynamic parameters were calculated for the minimum energy conformer at ab initio and DFT levels invoking 6-311G(d,p) basis set and the results are compared with the experimental values with the help of three specific scaling procedures, the observed vibrational wavenumbers in FTIR and FT-Raman spectra were analyzed and assigned to different normal modes of the molecule. Most of the modes have wavenumbers in the expected range, the error obtained was in general very low. The appropriate theoretical spectrograms for the FTIR spectra of the title molecule were also constructed.
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100
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Sundaraganesan N, Ayyappan S, Umamaheswari H, Joshua BD. FTIR, FT-Raman spectra and ab initio, DFT vibrational analysis of 2,4-dinitrophenylhydrazine. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 66:17-27. [PMID: 16815087 DOI: 10.1016/j.saa.2006.02.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2005] [Revised: 01/26/2006] [Accepted: 02/13/2006] [Indexed: 05/10/2023]
Abstract
The FTIR and FT-Raman spectra of 2,4-dinitrophenylhydrazine (2,4-DNPH) has been recorded in the region 4000-400 and 3500-50cm-1, respectively. The optimized geometry, frequency and intensity of the vibrational bands of 2,4-DNPH were obtained by the ab initio and density functional theory (DFT) levels of theory with complete relaxation in the potential energy surface using 6-31G(d,p) and 6-311G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.
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