Internal rotation dynamics of nitromethane at low temperatures

Mohaček-Grošev, Vlasta; Stelzer, Franz; Jocham, Daniel

doi:10.1016/s0022-2860(98)00527-4

Cited by 17 publications

(2 citation statements)

References 27 publications

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“…The resulting intensity function is usually denoted R(ω). Methyl libration bands are notoriously weak in Raman spectra [34], therefore the 80 cm −1 band is attributed to hydroxymethyl torsions. …”

Section: Hydroxyacetonementioning

confidence: 99%

Vibrational analysis of hydroxyacetone

Mohaček-Grošev

2005

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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In order to be able to fully understand the vibrational dynamics of monosaccharide sugars, we started with hydroxyacetone CH 2 OHCOCH 3, and glycolaldehyde CH 2 OHCOH, which are among the smallest molecules that contain hydroxyl and carbonyl group on neighboring carbon atoms. This sterical configuration is characteristic for saccharides and determines their biochemical activity. In this work vibrational analysis of hydroxyacetone was undertaken by performing the normal coordinate analysis for glycolaldehyde first, and transferring these force constants to hydroxyacetone. The observed Raman and infrared bands for 90 wt.% solution of hydroxyacetone in water (acetol) were used as a first approximation for the bands of free hydroxyacetone. The number of observed Raman and infrared bands for acetol exceeds the number of calculated values for the most stable hydroxyacetone conformer with C s symmetry, which suggests more than one conformer of hydroxyacetone in water solution. In particular, there are two bands both in infrared (1083 and 1057 cm −1 ) and in Raman spectrum (1086.5 and 1053 cm −1 ) that are assigned to the CO stretching mode and this is one of the indicators of several hydroxyacetone conformers in the solution. Additional information was obtained from low temperature Raman spectra: at 240 K a broad assymmetric band centered around 280 cm −1 appears, suggesting a disorder in the orientation of hydroxyl groups. Glassy state forms at ∼150 K. The broad band at 80 cm −1 is assigned to frozen torsions of hydroxymethyl groups.

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Section: Hydroxyacetonementioning

confidence: 99%

Vibrational analysis of hydroxyacetone

Mohaček-Grošev

2005

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…One may thus question the possibility of the existence of a glassy state in THF-such a type was predicted by the molecular dynamics simulation method employed by Rong-Ri et al [36], but ruled out after several attempts to achieve a vitrification in THF proved unsuccessful [35]. Cosidering that such a phase was found by Raman spectroscopy to exist in nitromethane in a very narrow temperature interval [37] and was not detected by the classical measurement of heat capacity [38], there is a possibility that tetrahydrofuran possesses such a phase as well.…”

Section: Resultsmentioning

confidence: 99%

Low Temperature Raman Spectroscopy of Tetrahydrofuran: Phonon Spectra Compared to Matrix Isolation Spectra in Air

Mohaček-Grošev

2024

Crystals

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The conformation of tetrahydrofuran (THF) molecules in vapor has been the subject of considerable computational and experimental studies, the most recent by Park and Kwon stated that the difference between the most stable, twisted C2 conformer and the bent Cs conformer is 17 ± 15 cm−1. Because of low symmetry, all modes from both conformers are allowed in the Raman and infrared spectra. In 1982, Aleksanyan and Antipov observed the emergence of two Raman bands at 249 and 303 cm−1 at 20 K, while only one band at 293 cm−1 was present in solid THF at 142. They assigned the 249 cm−1 band to the restricted pseudorotational motion of THF in the solid state, because on heating, the band diminishes and is too weak to be observed near melting point (at 142 K). Cadioli et al. reported a study of the vibrational spectrum of tetrahydrofuran, giving a complete assignment of all bands including those present in the low-temperature Raman spectrum at 85 K and infrared bands observed at 90 K. They assigned the band at 242 cm−1 in the Raman spectrum at 85 K as an overtone of the lowest normal mode (pseudorotational mode), while the 299 cm−1 band in the same spectrum was assigned as a radial mode. In the following, low-temperature Raman spectra of solid THF together with the Raman matrix isolated spectrum of THF in air will be presented and compared to published data. Our results indicate that the band observed at 245 cm−1 at 10 K is too strong to be assigned as an overtone, since its intensity is of the same magnitude as the 299 cm−1 band.

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Raman and infrared investigations at room temperature of the internal modes behaviour in solid nitromethane‐h₃ and ‐d₃ up to 45 GPa

Ouillon¹,

Pinan-Lucarré²,

Canny³

et al. 2007

J Raman Spectroscopy

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International audienceRaman and infrared spectra of internal phonons in solid nitromethane-h3 and -d3 were measured as a function of pressure in the range 0 – 40 GPa at room temperature. Experiments were performed in diamond anvil cells. The evolution of the splitting of the various modes in condition of nearly hydrostatic compression supports the maintenance of the P21 21 21 crystal structure until the material chemically transforms into an amorphous phase. The observed pressure-induced shifts of vibrational wavenumbers are consistent with computations recently reported in the literature. Infrared and Raman spectroscopies deliver complementary information on the internal modes behaviour. The continuous evolution of the infrared band shapes suggests a weak molecular distortion during the compression process. The strong modifications that are observed in the Raman bands of the nitro group are attributed to polarization effects arising from a rearrangement of the molecules inside the unit cell in the pressure range 10 – 12 GPa, a consequence of a close intermolecular O · · ·H approac

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Internal rotation dynamics of nitromethane at low temperatures

Cited by 17 publications

References 27 publications

Vibrational analysis of hydroxyacetone

Vibrational analysis of hydroxyacetone

Low Temperature Raman Spectroscopy of Tetrahydrofuran: Phonon Spectra Compared to Matrix Isolation Spectra in Air

Raman and infrared investigations at room temperature of the internal modes behaviour in solid nitromethane‐h₃ and ‐d₃ up to 45 GPa

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Internal rotation dynamics of nitromethane at low temperatures

Cited by 17 publications

References 27 publications

Vibrational analysis of hydroxyacetone

Vibrational analysis of hydroxyacetone

Low Temperature Raman Spectroscopy of Tetrahydrofuran: Phonon Spectra Compared to Matrix Isolation Spectra in Air

Raman and infrared investigations at room temperature of the internal modes behaviour in solid nitromethane‐h3 and ‐d3 up to 45 GPa

Contact Info

Product

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Raman and infrared investigations at room temperature of the internal modes behaviour in solid nitromethane‐h₃ and ‐d₃ up to 45 GPa