Why <i>tert</i>-Butyl Alcohol Associates in Aqueous Solution but Trimethylamine-<i>N</i>-oxide Does Not

Paul, Sandip; Patey, G. N.

doi:10.1021/jp0609378

Cited by 80 publications

(127 citation statements)

References 39 publications

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“…The strong hydration of TMAO has been previously demonstrated in both experiments and simulations. [30][31][32][33][34][35] Urea is a nearly ideal solute in aqueous solution (in the molar scale); is smaller and correspondingly shows more modest correlations with water.…”

Section: Resultsmentioning

confidence: 99%

Backbone additivity in the transfer model of protein solvation

et al. 2010

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The transfer model implying additivity of the peptide backbone free energy of transfer is computationally tested. Molecular dynamics simulations are used to determine the extent of change in transfer free energy (DG tr ) with increase in chain length of oligoglycine with capped end groups. Solvation free energies of oligoglycine models of varying lengths in pure water and in the osmolyte solutions, 2M urea and 2M trimethylamine N-oxide (TMAO), were calculated from simulations of all atom models, and DG tr values for peptide backbone transfer from water to the osmolyte solutions were determined. The results show that the transfer free energies change linearly with increasing chain length, demonstrating the principle of additivity, and provide values in reasonable agreement with experiment. The peptide backbone transfer free energy contributions arise from van der Waals interactions in the case of transfer to urea, but from electrostatics on transfer to TMAO solution. The simulations used here allow for the calculation of the solvation and transfer free energy of longer oligoglycine models to be evaluated than is currently possible through experiment. The peptide backbone unit computed transfer free energy of 254 cal/mol/M compares quite favorably with 243 cal/mol/M determined experimentally.

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Section: Resultsmentioning

confidence: 99%

Backbone additivity in the transfer model of protein solvation

et al. 2010

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“…The absence of clustering for TMAO agrees with the results of molecular dynamics simulations. 39 For TBA, the saturation effect is much stronger, indicating that these molecules cluster. For TBA, only the low concentration region can be fitted well to Eq.…”

Section: Discussionmentioning

confidence: 99%

“…16,4,20,39,40 MD simulations showed that for a mole fraction of 0.08, clusters of 3-4 TBA molecules were formed. 40 Neutron scattering studies for a TBA solution of 0.06 mol fraction also showed that clusters are formed with a size of 3 Ϯ 0.5 TBA molecules.…”

Section: Discussionmentioning

confidence: 99%

Femtosecond midinfrared study of aggregation behavior in aqueous solutions of amphiphilic molecules

Petersen

Bakulin

Pavelyev

et al. 2010

The Journal of Chemical Physics

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Femtosecond midinfrared study of aggregation behavior in aqueous solutions of amphiphilic molecules Petersen, C.; Bakulin, A.A.; Pavelyev, V.G.; Pshenichnikov, M.S.; Bakker, H.J. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We study the spectral and orientational dynamics of HDO molecules in aqueous solutions of different concentrations of tertiary butyl alcohol ͑TBA͒ and trimethylamine-N-oxide ͑TMAO͒. The spectral dynamics is investigated with femtosecond two-dimensional infrared spectroscopy of the O-H stretch vibration of HDO: D 2 O, and the orientational dynamics is studied with femtosecond polarization-resolved pump-probe spectroscopy of the O-D stretch vibration of HDO: H 2 O. Both the spectral and orientational dynamics are observed to show bimodal behavior: part of the water molecules shows spectral and orientational dynamics similar to bulk liquid water and part of the water molecules displays a much slower dynamics. For low solute concentrations, the latter fraction of slow water increases linearly as a function of solute molality, indicating that the slow water is contained in the solvation shells of TBA and TMAO. At higher concentrations, the fraction of slow water saturates. The saturation behavior is much stronger for TBA solutions than for TMAO solutions, indicating the aggregation of the TBA molecules.

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“…Indeed, several simulation studies [42][43][44][45][46][47][48][49][50] have been performed on this important binary mixture, at different concentrations and using different force fields. Early in the 1990's, Tanaka and Nakanishi [42] performed simulations on this system and noted self-aggregation of TBA molecules at mole fraction 0.17.…”

Section: Introductionmentioning

confidence: 99%

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Banerjee

Furtado

Bagchi

2014

The Journal of Chemical Physics

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Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ≈ 0.03 − 0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak non-linearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

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Why tert-Butyl Alcohol Associates in Aqueous Solution but Trimethylamine-N-oxide Does Not

Cited by 80 publications

References 39 publications

Backbone additivity in the transfer model of protein solvation

Backbone additivity in the transfer model of protein solvation

Femtosecond midinfrared study of aggregation behavior in aqueous solutions of amphiphilic molecules

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

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