Rotational Isomerism of Ethanol and Matrix Isolation Infrared Spectroscopy

Coussan, S.; Bouteiller, Y.; Perchard, J. P.; Zheng, Wanquan

doi:10.1021/jp9805961

Cited by 119 publications

(160 citation statements)

References 33 publications

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“…CPMD, ADF, B3LYP of Ref. [72], and MP4 [73] predict the trans conformer to be stable by 0.07-0.10 kcal/mol, in good agreement with the experimental value of 0.12 kcal/mol. In contrast, the B3LYP calculation of [70] yields the opposite, with the gauche conformer stable by 0.23 kcal/mol.…”

Section: Gas-phase Complexessupporting

confidence: 75%

“…Vibrational frequencies obtained by a Fourier transform of the velocity auto correlation function (VACF) of a single ethanol at 300 K yields an OH stretch frequency of 3200 cm −1 and a CH stretch frequencies in the range of 2600-2800 cm −1 . This should be compared to the experimental values of 3653 cm −1 [72], and 2800-3000 cm −1 [19,72], respectively. The tendency of BLYP to underestimate frequencies by ≈ 10% is a known feature, and also observed in BLYP calculations of water [50] and methanol [53].…”

Section: Gas-phase Complexesmentioning

confidence: 99%

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Ab initio molecular dynamics study of aqueous solvation of ethanol and ethylene

Erp

Meijer

2003

The Journal of Chemical Physics

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The structure and dynamics of aqueous solvation of ethanol and ethylene are studied by DFTbased Car-Parrinello molecular dynamics. We did not find an enhancement of the structure of the hydrogen bonded network of hydrating water molecules. Both ethanol and ethylene can easily be accommodated in the hydrogen-bonded network of water molecules without altering its structure. This is supports the conclusion from recent neutron diffraction experiments that there is no hydrophobic hydration around small hydrophobic groups. Analysis of the electronic charge distribution using Wannier functions shows that the dipole moment of ethanol increases from 1.8 D to 3.1 D upon solvation, while the apolar ethylene molecule attains an average dipole moment of 0.5 D. For ethylene, we identified configurations with π-H bonded water molecules, that have rare four-fold hydrogen-bonded water coordination, yielding instantaneous dipole moments of ethylene of up to 1 D. The results provide valuable information for the improvement of empirical force fields, and point out that for an accurate description of the aqueous solvation of ethanol, and even of the apolar ethylene, polarizable force fields are required.

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Section: Gas-phase Complexessupporting

confidence: 75%

Section: Gas-phase Complexesmentioning

confidence: 99%

Ab initio molecular dynamics study of aqueous solvation of ethanol and ethylene

Erp

Meijer

2003

The Journal of Chemical Physics

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“…11,[14][15][16][17][18][19][20] A detailed study by Perchard and Josien 14,15 examined gas, diluted solution, liquid, and solid state phases of ethanol, reporting 19 different vibrational bands. Assignment was made difficult based on coupling between the vibrational modes observed in each phase.…”

Section: Introductionmentioning

confidence: 99%

The adsorption and desorption of ethanol ices from a model grain surface

Burke

Wolff

Edridge

et al. 2008

The Journal of Chemical Physics

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Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Reflection absorption infrared spectroscopy ͑RAIRS͒ and temperature programed desorption ͑TPD͒ have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite ͑HOPG͒ at 98 K. RAIR spectra for ethanol show that it forms physisorbed multilayers on the surface at 98 K. Annealing multilayer ethanol ices ͑exposures Ͼ50 L͒ beyond 120 K gives rise to a change in morphology before crystallization within the ice occurs. TPD shows that ethanol adsorbs and desorbs molecularly on the HOPG surface and shows four different species in desorption. At low coverage, desorption of monolayer ethanol is observed and is described by first-order kinetics. With increasing coverage, a second TPD peak is observed at a lower temperature, which is assigned to an ethanol bilayer. When the coverage is further increased, a second multilayer, less strongly bound to the underlying ethanol ice film, is observed. This peak dominates the TPD spectra with increasing coverage and is characterized by fractional-order kinetics and a desorption energy of 56.3Ϯ 1.7 kJ mol −1 . At exposures exceeding 50 L, formation of crystalline ethanol is also observed as a high temperature shoulder on the TPD spectrum at 160 K.

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“…However, these calculations apply to the vacuum. In a matrix, due to environment effects, a change in the relative energies of the conformers can occur, 16 and it is difficult to predict a priori which of the forms will become more stable. The definite answer for the question of the most stable conformers in the families G 0 G 0 (5 or 6) and GT (7 or 8) can only be obtained from the experiment.…”

mentioning

confidence: 99%

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

Reva

Jesus

Rosado

et al. 2006

Phys. Chem. Chem. Phys.

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The present work explores the possibilities of the matrix isolation technique in the structural characterisation of highly flexible molecules. To date, most studies of this type were carried out on molecules with three or less internal degrees of freedom and a few (less than 10) possible conformations. The molecule of 1,2-butanediol has four conformationally relevant three-fold rotational axes, which can result in 81 possible conformations. A detailed theoretical study, at the MP2 and DFT(B3LYP) levels of theory with the 6-311++G(d,p) basis set, revealed that more than 20 conformers of 1,2-butanediol have relative energies in a 0-10 kJ mol À1 range and contribute appreciably to the gas phase equilibrium at room temperature. This fact renders conformational studies of the system extremely difficult under normal conditions. However, the method of matrix isolation permits the reduction of the number of populated conformational states in the experiment at low temperature due to the effect known as conformational cooling: low energy barriers promote the relaxation of the higher energy local minima into more stable structures. As a result of massive conformational cooling occurring upon matrix deposition, only five conformers of 1,2-butanediol were retained in the samples at 10 K. These conformers were identified using a combination of FTIR spectroscopy and extensive theoretical calculations of vibrational spectra. Annealing of the matrices up to 50 K resulted in the extreme case of conformational cooling related with the depopulation of all conformers into the most stable unique structure. The observed transformations were rationalized in terms of barriers to intramolecular rotation.

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Rotational Isomerism of Ethanol and Matrix Isolation Infrared Spectroscopy

Cited by 119 publications

References 33 publications

Ab initio molecular dynamics study of aqueous solvation of ethanol and ethylene

Ab initio molecular dynamics study of aqueous solvation of ethanol and ethylene

The adsorption and desorption of ethanol ices from a model grain surface

Stepwise conformational cooling towards a single isomeric state in the four internal rotors system 1,2-butanediol

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