Effect of solvation and confinement on the trans-gauche isomerization reaction in n-butane

Travis, Karl P. and Searles, Debra J. (2006) Effect of solvation and confinement on the trans-gauche isomerization reaction in n-butane. Journal of Chemical Physics, 125 16 Article No.164501: . doi:10.1063/1.2363380

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Author Travis, Karl P.
Searles, Debra J.
Title Effect of solvation and confinement on the trans-gauche isomerization reaction in n-butane
Journal name Journal of Chemical Physics   Check publisher's open access policy
ISSN 0021-9606
Publication date 2006-10-01
Sub-type Article (original research)
DOI 10.1063/1.2363380
Open Access Status File (Publisher version)
Volume 125
Issue 16 Article No.164501
Total pages 15
Place of publication College Park, MD United States
Publisher American Institute of Physics
Language eng
Formatted abstract
The effect of solvation and confinement on the conformational equilibria and kinetics of n -butane is examined using molecular dynamics simulations of the bulk and confined fluids and compared to appropriately chosen reference states. Clear evidence for a solvent shift of the preferred conformation in bulk n -butane is found. At a temperature of 292 K and a density of 6.05 nm-3 a small solvent shift in favor of gauche is observed (similar to previously reported values), and the shift increases substantially with an increase in density to 8.28 nm-3. The rate of torsional interconversion from the trans to the gauche state, calculated using the relaxation function method, was found to increase with increasing temperature and density. The rate constants kTG and kGT have an Arrhenius temperature dependence yielding activation energies significantly lower than the trans-gauche and gauche-trans barrier heights in the torsional potential for a free molecule, depending on the density. In the confined phase, we considered the same densities as simulated in the bulk phase, and for four different values of the physical pore width (∼1.5-4.0 nm). At the high density, we find that the position of the trans-gauche equilibrium is displaced towards excess trans compared with the bulk phase, reflecting the confinement and interactions of the molecules with the pore wall. The isomerization rate is found to decrease with decreasing pore width. Again, we find that the kinetics obeys an Arrhenius rate law and the activation energy for the trans-gauche and gauche-trans interconversions is slightly smaller than that of the bulk fluid at the same density
Keyword Molecular-Dynamics Simulations
Chemical-Reaction Equilibria
Conformational Kinetics
State Approximation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Australian Institute for Bioengineering and Nanotechnology Publications
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
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