Gábor Keresztury - Profile on Academia.edu (original) (raw)
Papers by Gábor Keresztury
Vibrational coupling in trans-azobenzene and its isotopomers
Journal of Molecular Structure, 1997
Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, i... more Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, including the parent one, were recorded. Using mono and double 15N-labelled isotopomers, the assignment of the NN stretching was confirmed at 1439 cm−1 in the parent isotopomer. This vibration is strongly coupled with the phenyl mode 19b. In isotopomers with one and two perdeuterium-labelled phenyl groups the NN
Journal of Biochemical and Biophysical Methods, 2004
The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone der... more The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone derivatives were analyzed with the aim of pointing out the differences in vibrational behavior of their coexisting stable conformers. Quantum mechanical (QM) density functional (DFT/ B3LYP/6-31*) and normal coordinate calculations were carried out to establish the equilibrium structures and to facilitate the interpretation of the vibrational spectra of the 2V-pyrrolyl and 2Vnitrophenyl derivatives. The frequencies and intensities calculated according to the scaled quantum mechanical (SQM) force field method were used to simulate the IR and Raman spectra and compare them to the measured ones. The results demonstrate that the adopted methodology is capable of treating these fairly large polycyclic molecules. The resulting spectral simulations and detailed vibrational description can be highly useful in clarifying spectral differences brought about by cistrans isomerism and indicating the extent of spectral changes due to further conformational changes of the aryl substituent attached to the olefinic CMC bond. D
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
The vibrational spectra of 3,4-diamino benzophenone (DABP) have been computed using B3LYP methodo... more The vibrational spectra of 3,4-diamino benzophenone (DABP) have been computed using B3LYP methodology and 6-31G* and 6-31G** basis sets. The solid phase FTIR and FT-Raman spectra were recorded in the region 4000-400 cm −1 and 3500-100 cm −1 , respectively. A close agreement was achieved between the observed and calculated frequencies by employing normal coordinate calculations. The observed and simulated spectra were found to be well comparable.
Hydrogen bonding and molecular vibrations of 3,5-diamino-1,2,4-triazole
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-dia... more This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-diamino-1,2,4-triazole by means of quantum chemical calculations. The mid and far FTIR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational frequencies were calculated under different possible symmetries by applying the density functional theory with the B3LYP functional and the 6-31G* basis set. The results of the calculations obtained under C(2) symmetry produces the global minimum on the potential energy surface. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The infrared and Raman spectra were also predicted from the calculated intensities.
Near-infrared Fourier transform Raman spectra of protonated and deuterated trans-azobenzene isotopomers
Journal of Molecular Structure, 1997
Near-infrared Fourier transform (NIR FT) Raman spectra of five trans-azobenzene isotopomers and t... more Near-infrared Fourier transform (NIR FT) Raman spectra of five trans-azobenzene isotopomers and their protonated and deuterated forms were recorded. Trifluoroacetic acid was found to be a good protonation agent for measuring Raman spectra of protonated azobenzene. An assignment of the most relevant vibrational modes (NN stretching and NHN2H in-plane bending) of the protonated and deuterated species is proposed. The NN
Because different authors construct composite torsional coordinates differently, torsional force ... more Because different authors construct composite torsional coordinates differently, torsional force constant values reported for the same or very similar internal rotors differ from each other by as much as one or occasionally two orders of magnitude. Since these coordinates are not always precisely defined, the source of the discrepancies cannot always be delineated. Examples are given which show how the recommended torsional coordinate (IUPAC Commission on Molecular Spectroscopy) ensures that the G and F matrix values for the same internal rotor in different surroundings stay comparable. The other types of torsional coordinates which are frequently used lead to inconsistent results even with the same molecule. A similar problem can also exist for the twisting coordinate.
Inorganica Chimica Acta, 2007
A comparative structural study on sodium and potassium N-chloroarenesulfonamidates has been carri... more A comparative structural study on sodium and potassium N-chloroarenesulfonamidates has been carried out using X-ray diffraction and IR spectroscopy as experimental techniques. As shown by crystallographic studies, the sodium ions tend to incorporate more water oxygen atoms in their coordination spheres than the potassium ions, while the potassium congeners prefer the interaction with sulfonamidate moieties. The marked dissimilarity between the
Journal of Molecular Structure, 1995
The vibrational analysis of cis-stilbene in the ground electronic state based on the infrared and... more The vibrational analysis of cis-stilbene in the ground electronic state based on the infrared and Raman spectra of a series of its isotopomers and scaled semiempirical AM1 calculations is reported. The CαCα stretching, all the four CαH deformations and the CαCα torsion are described. A comparison with trans-stilbene shows a much lesser degree of couplings between olefinic and phenyl vibrations
Intramolecular vibrational coupling in the ground electronic state (S0) of trans-stilbene
The Journal of Physical Chemistry, 1990
8th Intl Conf on Fourier Transform Spectroscopy, 1992
ABSTRACT CO chemisorbed on totally non-transparent and non-reflecting Pd powder has been successf... more ABSTRACT CO chemisorbed on totally non-transparent and non-reflecting Pd powder has been successfully measured by emission techniques.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2002
FT-IR, FT-Raman and FT-SERS spectra of 4-aminosalicylic acid sodium salt dihydrate (4ASAS) have b... more FT-IR, FT-Raman and FT-SERS spectra of 4-aminosalicylic acid sodium salt dihydrate (4ASAS) have been recorded and analysed. The vibrational bands due to NH 2 , OH, carboxyl group, and the benzene ring are identified. The CX ipb(17a, 17b), CC ipb(6,18a) and CH ipb (3,14a, 14b) bands are more enhanced in SERS. Broadening of the inplane carboxyl bend indicates interaction with the silver surface. Further the wC O, w(C O) c and w(C O) h are intense in the SERS spectrum. The rocking and wagging modes of NH 2 also show up in SERS. The molecule (O, N donor ligand) is thought to adsorb through the carboxyl oxygen atom with the benzene ring in a 'perpendicular side on orientation' with respect to the silver surface.
Journal of Molecular Structure - J MOL STRUCT, 2004
The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal... more The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal), and vapor phase GC/IR spectra of 2-(methylthio)benzonitrile have been recorded in the regions 4000–50, 3500–100, 4000–400, and 4000–650 cm−1, respectively. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimizations and force field calculations based on density functional theory (DFT) using standard B3LYP/6-31G* and B3LYP/6-311+G** method and basis set combinations. Normal coordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. IR dichroism data revealed an error in band assignment associated with a νCS vibration, which could be eliminated only by introducing independent scaling factors for sulfur, whereas the overall frequency fit was further improved. Simulation of infrared and Raman spectra utilizing...
 2 . A Low Temperature Synthesis Route of the CdMn 2 O 4+ x Type NO x and CH 3 SH Sensor Precursors](https://attachments.academia-assets.com/45307852/thumbnails/1.jpg)
](Zeitschrift für anorganische und allgemeine Chemie, 2012
Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidat... more Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidated with XRD-Rietveld refinement and vibrational spectroscopic methods. Compound 1 has a cubic lattice consisting of a 3D hydrogen-bonded network built as four by four distorted tetrahedral blocks of [Cd(NH 3 ) 4 ] 2+ cations and MnO 4 anions, respectively. The other four permanganate ions are located in a crystallographically different environment, placed in the cavities formed by the attachment of the building blocks. A low-temperature (≈100°C) solid phase quasi-intramolecular redox reaction producing ammonium nitrate and amorphous CdMn 2 O 4 could be established. Neither solid phase nor aqueous solution phase thermal deammoniation of compound
Role of Secondary Interactions in the Conformational Equilibrium of 2,6-Diisopropylphenol
The Journal of Physical Chemistry A, 2001
... Physical Chemistry A: Energetic and Structural Study of Diphenylpyridine Isomers.Marisa AA Ro... more ... Physical Chemistry A: Energetic and Structural Study of Diphenylpyridine Isomers.Marisa AA Rocha, Lígia R. Gomes, John N. Low and Luís MNBF Santos. The Journal of Physical Chemistry A 2009 113 (41), pp 11015–11027. ...
Hydrogen bonding and molecular vibrations of 3,5-diamino-1,2,4-triazole
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-dia... more This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-diamino-1,2,4-triazole by means of quantum chemical calculations. The mid and far FTIR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational frequencies were calculated under different possible symmetries by applying the density functional theory with the B3LYP functional and the 6-31G* basis set. The results of the calculations obtained under C(2) symmetry produces the global minimum on the potential energy surface. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The infrared and Raman spectra were also predicted from the calculated intensities.
Journal of Solid State Chemistry, 1991
IR and Raman spectra of BaCd(HCOO)d. 2H20 have been recorded and analyzed. Observation of three s... more IR and Raman spectra of BaCd(HCOO)d. 2H20 have been recorded and analyzed. Observation of three separate frequencies for every internal mode of the formate ion is indicative of three crystallographically nonequivalent formate ions. The frequency of the in-plane C-H bending mode is found to be higher than the symmetric CO, stretching mode. The correlation field effect is observed to be small. D 1991 Academic Press. Inc.
Journal of Biochemical and Biophysical Methods, 2004
The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone der... more The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone derivatives were analyzed with the aim of pointing out the differences in vibrational behavior of their coexisting stable conformers. Quantum mechanical (QM) density functional (DFT/ B3LYP/6-31*) and normal coordinate calculations were carried out to establish the equilibrium structures and to facilitate the interpretation of the vibrational spectra of the 2V-pyrrolyl and 2Vnitrophenyl derivatives. The frequencies and intensities calculated according to the scaled quantum mechanical (SQM) force field method were used to simulate the IR and Raman spectra and compare them to the measured ones. The results demonstrate that the adopted methodology is capable of treating these fairly large polycyclic molecules. The resulting spectral simulations and detailed vibrational description can be highly useful in clarifying spectral differences brought about by cistrans isomerism and indicating the extent of spectral changes due to further conformational changes of the aryl substituent attached to the olefinic CMC bond. D
Journal of Molecular Structure, 2004
The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal... more The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal), and vapor phase GC/IR spectra of 2-(methylthio)benzonitrile have been recorded in the regions 4000-50, 3500-100, 4000-400, and 4000-650 cm 21 , respectively. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimizations and force field calculations based on density functional theory (DFT) using standard B3LYP/6-31G* and B3LYP/6-311 þ G** method and basis set combinations. Normal coordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. IR dichroism data revealed an error in band assignment associated with a nCS vibration, which could be eliminated only by introducing independent scaling factors for sulfur, whereas the overall frequency fit was further improved. Simulation of infrared and Raman spectra utilizing the results of these calculations led to excellent overall agreement with the observed spectral patterns, especially with the higher level basis set. The SQM approach applying selective scaling of the DFT force field was shown to be superior to the uniform scaling method in its ability to allow for making modifications in the band assignment, resulting in more accurate simulation of IR and Raman spectra including band polarizations and intensity patterns. q
Vibrational coupling in trans-azobenzene and its isotopomers
Journal of Molecular Structure, 1997
Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, i... more Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, including the parent one, were recorded. Using mono and double 15N-labelled isotopomers, the assignment of the NN stretching was confirmed at 1439 cm−1 in the parent isotopomer. This vibration is strongly coupled with the phenyl mode 19b. In isotopomers with one and two perdeuterium-labelled phenyl groups the NN
Emission FT-IR spectroscopic study of adsorbed carbon monoxide on metal powders and supported catalysts
Journal of Molecular Structure, 1997
Fourier transform infrared emission spectroscopy, FT-IRES, was used for the detection of adsorbed... more Fourier transform infrared emission spectroscopy, FT-IRES, was used for the detection of adsorbed CO species at p = 40 mbar and T = 333–393 K on metal powders (Pt, Pd, Rh) and supported catalysts (Rh/activated carbon, 5% Rh). Linearly bonded CO features were detected at 2020 and 2030 cm−1 for Pd and Pt respectively. Bridged carbonly species were also detected for Pd and Pt at 1930 and 1920 cm−1 respectively. The bands observed for Rh powder at 2040 and 1970 cm−1 have been assigned to symmetric and asymmetric stretchings of the geminal dicarbonyl, and the band at 1860 cm−1 is ascribed to the bridged carbonyl species. Similar bands, but about ten times weaker, have been observed for carbon supported Rh, and an extreme feature appeared at about 1800 cm−1 that might indicate the existence of three-fold bridged species.
Vibrational coupling in trans-azobenzene and its isotopomers
Journal of Molecular Structure, 1997
Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, i... more Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, including the parent one, were recorded. Using mono and double 15N-labelled isotopomers, the assignment of the NN stretching was confirmed at 1439 cm−1 in the parent isotopomer. This vibration is strongly coupled with the phenyl mode 19b. In isotopomers with one and two perdeuterium-labelled phenyl groups the NN
Journal of Biochemical and Biophysical Methods, 2004
The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone der... more The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone derivatives were analyzed with the aim of pointing out the differences in vibrational behavior of their coexisting stable conformers. Quantum mechanical (QM) density functional (DFT/ B3LYP/6-31*) and normal coordinate calculations were carried out to establish the equilibrium structures and to facilitate the interpretation of the vibrational spectra of the 2V-pyrrolyl and 2Vnitrophenyl derivatives. The frequencies and intensities calculated according to the scaled quantum mechanical (SQM) force field method were used to simulate the IR and Raman spectra and compare them to the measured ones. The results demonstrate that the adopted methodology is capable of treating these fairly large polycyclic molecules. The resulting spectral simulations and detailed vibrational description can be highly useful in clarifying spectral differences brought about by cistrans isomerism and indicating the extent of spectral changes due to further conformational changes of the aryl substituent attached to the olefinic CMC bond. D
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
The vibrational spectra of 3,4-diamino benzophenone (DABP) have been computed using B3LYP methodo... more The vibrational spectra of 3,4-diamino benzophenone (DABP) have been computed using B3LYP methodology and 6-31G* and 6-31G** basis sets. The solid phase FTIR and FT-Raman spectra were recorded in the region 4000-400 cm −1 and 3500-100 cm −1 , respectively. A close agreement was achieved between the observed and calculated frequencies by employing normal coordinate calculations. The observed and simulated spectra were found to be well comparable.
Hydrogen bonding and molecular vibrations of 3,5-diamino-1,2,4-triazole
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-dia... more This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-diamino-1,2,4-triazole by means of quantum chemical calculations. The mid and far FTIR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational frequencies were calculated under different possible symmetries by applying the density functional theory with the B3LYP functional and the 6-31G* basis set. The results of the calculations obtained under C(2) symmetry produces the global minimum on the potential energy surface. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The infrared and Raman spectra were also predicted from the calculated intensities.
Near-infrared Fourier transform Raman spectra of protonated and deuterated trans-azobenzene isotopomers
Journal of Molecular Structure, 1997
Near-infrared Fourier transform (NIR FT) Raman spectra of five trans-azobenzene isotopomers and t... more Near-infrared Fourier transform (NIR FT) Raman spectra of five trans-azobenzene isotopomers and their protonated and deuterated forms were recorded. Trifluoroacetic acid was found to be a good protonation agent for measuring Raman spectra of protonated azobenzene. An assignment of the most relevant vibrational modes (NN stretching and NHN2H in-plane bending) of the protonated and deuterated species is proposed. The NN
Because different authors construct composite torsional coordinates differently, torsional force ... more Because different authors construct composite torsional coordinates differently, torsional force constant values reported for the same or very similar internal rotors differ from each other by as much as one or occasionally two orders of magnitude. Since these coordinates are not always precisely defined, the source of the discrepancies cannot always be delineated. Examples are given which show how the recommended torsional coordinate (IUPAC Commission on Molecular Spectroscopy) ensures that the G and F matrix values for the same internal rotor in different surroundings stay comparable. The other types of torsional coordinates which are frequently used lead to inconsistent results even with the same molecule. A similar problem can also exist for the twisting coordinate.
Inorganica Chimica Acta, 2007
A comparative structural study on sodium and potassium N-chloroarenesulfonamidates has been carri... more A comparative structural study on sodium and potassium N-chloroarenesulfonamidates has been carried out using X-ray diffraction and IR spectroscopy as experimental techniques. As shown by crystallographic studies, the sodium ions tend to incorporate more water oxygen atoms in their coordination spheres than the potassium ions, while the potassium congeners prefer the interaction with sulfonamidate moieties. The marked dissimilarity between the
Journal of Molecular Structure, 1995
The vibrational analysis of cis-stilbene in the ground electronic state based on the infrared and... more The vibrational analysis of cis-stilbene in the ground electronic state based on the infrared and Raman spectra of a series of its isotopomers and scaled semiempirical AM1 calculations is reported. The CαCα stretching, all the four CαH deformations and the CαCα torsion are described. A comparison with trans-stilbene shows a much lesser degree of couplings between olefinic and phenyl vibrations
Intramolecular vibrational coupling in the ground electronic state (S0) of trans-stilbene
The Journal of Physical Chemistry, 1990
8th Intl Conf on Fourier Transform Spectroscopy, 1992
ABSTRACT CO chemisorbed on totally non-transparent and non-reflecting Pd powder has been successf... more ABSTRACT CO chemisorbed on totally non-transparent and non-reflecting Pd powder has been successfully measured by emission techniques.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2002
FT-IR, FT-Raman and FT-SERS spectra of 4-aminosalicylic acid sodium salt dihydrate (4ASAS) have b... more FT-IR, FT-Raman and FT-SERS spectra of 4-aminosalicylic acid sodium salt dihydrate (4ASAS) have been recorded and analysed. The vibrational bands due to NH 2 , OH, carboxyl group, and the benzene ring are identified. The CX ipb(17a, 17b), CC ipb(6,18a) and CH ipb (3,14a, 14b) bands are more enhanced in SERS. Broadening of the inplane carboxyl bend indicates interaction with the silver surface. Further the wC O, w(C O) c and w(C O) h are intense in the SERS spectrum. The rocking and wagging modes of NH 2 also show up in SERS. The molecule (O, N donor ligand) is thought to adsorb through the carboxyl oxygen atom with the benzene ring in a 'perpendicular side on orientation' with respect to the silver surface.
Journal of Molecular Structure - J MOL STRUCT, 2004
The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal... more The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal), and vapor phase GC/IR spectra of 2-(methylthio)benzonitrile have been recorded in the regions 4000–50, 3500–100, 4000–400, and 4000–650 cm−1, respectively. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimizations and force field calculations based on density functional theory (DFT) using standard B3LYP/6-31G* and B3LYP/6-311+G** method and basis set combinations. Normal coordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. IR dichroism data revealed an error in band assignment associated with a νCS vibration, which could be eliminated only by introducing independent scaling factors for sulfur, whereas the overall frequency fit was further improved. Simulation of infrared and Raman spectra utilizing...
Zeitschrift für anorganische und allgemeine Chemie, 2012
Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidat... more Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidated with XRD-Rietveld refinement and vibrational spectroscopic methods. Compound 1 has a cubic lattice consisting of a 3D hydrogen-bonded network built as four by four distorted tetrahedral blocks of [Cd(NH 3 ) 4 ] 2+ cations and MnO 4 anions, respectively. The other four permanganate ions are located in a crystallographically different environment, placed in the cavities formed by the attachment of the building blocks. A low-temperature (≈100°C) solid phase quasi-intramolecular redox reaction producing ammonium nitrate and amorphous CdMn 2 O 4 could be established. Neither solid phase nor aqueous solution phase thermal deammoniation of compound
Role of Secondary Interactions in the Conformational Equilibrium of 2,6-Diisopropylphenol
The Journal of Physical Chemistry A, 2001
... Physical Chemistry A: Energetic and Structural Study of Diphenylpyridine Isomers.Marisa AA Ro... more ... Physical Chemistry A: Energetic and Structural Study of Diphenylpyridine Isomers.Marisa AA Rocha, Lígia R. Gomes, John N. Low and Luís MNBF Santos. The Journal of Physical Chemistry A 2009 113 (41), pp 11015–11027. ...
Hydrogen bonding and molecular vibrations of 3,5-diamino-1,2,4-triazole
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005
This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-dia... more This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-diamino-1,2,4-triazole by means of quantum chemical calculations. The mid and far FTIR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational frequencies were calculated under different possible symmetries by applying the density functional theory with the B3LYP functional and the 6-31G* basis set. The results of the calculations obtained under C(2) symmetry produces the global minimum on the potential energy surface. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The infrared and Raman spectra were also predicted from the calculated intensities.
Journal of Solid State Chemistry, 1991
IR and Raman spectra of BaCd(HCOO)d. 2H20 have been recorded and analyzed. Observation of three s... more IR and Raman spectra of BaCd(HCOO)d. 2H20 have been recorded and analyzed. Observation of three separate frequencies for every internal mode of the formate ion is indicative of three crystallographically nonequivalent formate ions. The frequency of the in-plane C-H bending mode is found to be higher than the symmetric CO, stretching mode. The correlation field effect is observed to be small. D 1991 Academic Press. Inc.
Journal of Biochemical and Biophysical Methods, 2004
The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone der... more The infrared and Raman spectra of resolved E and Z isomers of some 4-arylidene-3isochromanone derivatives were analyzed with the aim of pointing out the differences in vibrational behavior of their coexisting stable conformers. Quantum mechanical (QM) density functional (DFT/ B3LYP/6-31*) and normal coordinate calculations were carried out to establish the equilibrium structures and to facilitate the interpretation of the vibrational spectra of the 2V-pyrrolyl and 2Vnitrophenyl derivatives. The frequencies and intensities calculated according to the scaled quantum mechanical (SQM) force field method were used to simulate the IR and Raman spectra and compare them to the measured ones. The results demonstrate that the adopted methodology is capable of treating these fairly large polycyclic molecules. The resulting spectral simulations and detailed vibrational description can be highly useful in clarifying spectral differences brought about by cistrans isomerism and indicating the extent of spectral changes due to further conformational changes of the aryl substituent attached to the olefinic CMC bond. D
Journal of Molecular Structure, 2004
The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal... more The solid phase FT-IR and FT-Raman, solution phase linear dichroism IR (in nematic liquid crystal), and vapor phase GC/IR spectra of 2-(methylthio)benzonitrile have been recorded in the regions 4000-50, 3500-100, 4000-400, and 4000-650 cm 21 , respectively. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimizations and force field calculations based on density functional theory (DFT) using standard B3LYP/6-31G* and B3LYP/6-311 þ G** method and basis set combinations. Normal coordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. IR dichroism data revealed an error in band assignment associated with a nCS vibration, which could be eliminated only by introducing independent scaling factors for sulfur, whereas the overall frequency fit was further improved. Simulation of infrared and Raman spectra utilizing the results of these calculations led to excellent overall agreement with the observed spectral patterns, especially with the higher level basis set. The SQM approach applying selective scaling of the DFT force field was shown to be superior to the uniform scaling method in its ability to allow for making modifications in the band assignment, resulting in more accurate simulation of IR and Raman spectra including band polarizations and intensity patterns. q
Vibrational coupling in trans-azobenzene and its isotopomers
Journal of Molecular Structure, 1997
Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, i... more Infrared (4000−400 cm−1) and Raman spectra (4000−100 cm−1) of six trans-azobenzene isotopomers, including the parent one, were recorded. Using mono and double 15N-labelled isotopomers, the assignment of the NN stretching was confirmed at 1439 cm−1 in the parent isotopomer. This vibration is strongly coupled with the phenyl mode 19b. In isotopomers with one and two perdeuterium-labelled phenyl groups the NN
Emission FT-IR spectroscopic study of adsorbed carbon monoxide on metal powders and supported catalysts
Journal of Molecular Structure, 1997
Fourier transform infrared emission spectroscopy, FT-IRES, was used for the detection of adsorbed... more Fourier transform infrared emission spectroscopy, FT-IRES, was used for the detection of adsorbed CO species at p = 40 mbar and T = 333–393 K on metal powders (Pt, Pd, Rh) and supported catalysts (Rh/activated carbon, 5% Rh). Linearly bonded CO features were detected at 2020 and 2030 cm−1 for Pd and Pt respectively. Bridged carbonly species were also detected for Pd and Pt at 1930 and 1920 cm−1 respectively. The bands observed for Rh powder at 2040 and 1970 cm−1 have been assigned to symmetric and asymmetric stretchings of the geminal dicarbonyl, and the band at 1860 cm−1 is ascribed to the bridged carbonyl species. Similar bands, but about ten times weaker, have been observed for carbon supported Rh, and an extreme feature appeared at about 1800 cm−1 that might indicate the existence of three-fold bridged species.