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Do the solvent properties affect the propensity for self-association of α-cyclodextrin? Insights from NMR self-diffusion

Valente, Artur J.M. and Söderman, Olle LU (2019) In Journal of Molecular Liquids 295.
Abstract

Whether cyclodextrins (CDs) self-aggregate or not in solution is an interesting and timely scientific question. Yet, we are far from a scientific consensus as regards the nature of the phenomenon. Those who are in favor of the formation of CD aggregates justify the phenomenon by the presence of H-bonds, occurring between the hydroxyl groups located at both rims of cyclodextrins. To gain further insight with regard to the importance of these intermolecular CD-CD interactions, a systematic study of 1H NMR self-diffusion of α-cyclodextrin in binary mixtures of deuterated DMSO and water, at different mole fractions, has been carried out. The choice of these solvents was made based on their different degree of polarity and the... (More)

Whether cyclodextrins (CDs) self-aggregate or not in solution is an interesting and timely scientific question. Yet, we are far from a scientific consensus as regards the nature of the phenomenon. Those who are in favor of the formation of CD aggregates justify the phenomenon by the presence of H-bonds, occurring between the hydroxyl groups located at both rims of cyclodextrins. To gain further insight with regard to the importance of these intermolecular CD-CD interactions, a systematic study of 1H NMR self-diffusion of α-cyclodextrin in binary mixtures of deuterated DMSO and water, at different mole fractions, has been carried out. The choice of these solvents was made based on their different degree of polarity and the fact that they are miscible at any molar ratio. The experimental α-CD diffusion coefficients scale with the solution viscosity. Moreover, hydrodynamic radii of α-CD are independent of the solvent composition. No evidence of α-cyclodextrin aggregation at any DMSO mole fraction is found. Finally, experimental diffusion data are compared with those obtained from atomic level hydrodynamic calculations. In addition, diffusion coefficients of heavy water and DMSO in binary mixed solvents are also measured and analyzed. The obtained diffusion coefficients for DMSOd6 and D2O show a minimum at the eutectic composition and depend on the solution viscosity. The experimental results are compared with published molecular dynamic simulations.

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Contribution to journal
publication status
published
subject
keywords
DMSO, PFG NMR, Self-diffusion coefficients, Water, α-Cyclodextrin
in
Journal of Molecular Liquids
volume
295
article number
111869
publisher
Elsevier
external identifiers
  • scopus:85072898477
ISSN
0167-7322
DOI
10.1016/j.molliq.2019.111869
language
English
LU publication?
yes
id
dccb32a3-2017-471d-b405-bd3ca9c33faa
date added to LUP
2019-10-15 09:24:45
date last changed
2020-01-13 02:27:49
@article{dccb32a3-2017-471d-b405-bd3ca9c33faa,
  abstract     = {<p>Whether cyclodextrins (CDs) self-aggregate or not in solution is an interesting and timely scientific question. Yet, we are far from a scientific consensus as regards the nature of the phenomenon. Those who are in favor of the formation of CD aggregates justify the phenomenon by the presence of H-bonds, occurring between the hydroxyl groups located at both rims of cyclodextrins. To gain further insight with regard to the importance of these intermolecular CD-CD interactions, a systematic study of <sup>1</sup>H NMR self-diffusion of α-cyclodextrin in binary mixtures of deuterated DMSO and water, at different mole fractions, has been carried out. The choice of these solvents was made based on their different degree of polarity and the fact that they are miscible at any molar ratio. The experimental α-CD diffusion coefficients scale with the solution viscosity. Moreover, hydrodynamic radii of α-CD are independent of the solvent composition. No evidence of α-cyclodextrin aggregation at any DMSO mole fraction is found. Finally, experimental diffusion data are compared with those obtained from atomic level hydrodynamic calculations. In addition, diffusion coefficients of heavy water and DMSO in binary mixed solvents are also measured and analyzed. The obtained diffusion coefficients for DMSOd<sub>6</sub> and D<sub>2</sub>O show a minimum at the eutectic composition and depend on the solution viscosity. The experimental results are compared with published molecular dynamic simulations.</p>},
  author       = {Valente, Artur J.M. and Söderman, Olle},
  issn         = {0167-7322},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Journal of Molecular Liquids},
  title        = {Do the solvent properties affect the propensity for self-association of α-cyclodextrin? Insights from NMR self-diffusion},
  url          = {http://dx.doi.org/10.1016/j.molliq.2019.111869},
  doi          = {10.1016/j.molliq.2019.111869},
  volume       = {295},
  year         = {2019},
}