Ed Navarre - Complexation of phosphine ligands with peracetylated-β-cyclodextrin in supercritical carbon dioxide: Effect of temperature and cosolvent on the equilibrium constant.

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      Publication Details (including relevant citation   information):

      Galia, A.; Navarre, E. C.; Scialdone, O.; Filardo, G. &   Monflier, E. The Journal of Supercritical Fluids.   49, 154-160, 2009

      Abstract:

      The interaction between peracetylated-[beta]-cyclodextrin and   tert-butyl and adamantyl functionalized triphenylphosphine   derivatives was studied in supercritical carbon dioxide (scCO2)   based solvent media by UV-vis spectroscopy. The equilibrium   constant for a 1:1 complexation reaction was obtained from   titration spectra both in pure carbon dioxide and in the presence   of methanol as a cosolvent in the temperature range 308-323 K to   estimate the internal energy and entropy of the inclusion   equilibrium. The values of the equilibrium constants were found   significantly smaller than those obtained in aqueous solution   with analogous phosphines and substantially independent of the   nature of the phosphine and of the solvent medium. On the basis   of the results that we have obtained in this study we do believe   that a possible explanation of the unfavorable complexation   equilibria in CO2 based solvent systems could be a distorsion of   the conformation of the cyclic oligosaccharides arising from the   vanishing of the hydrogen bond interactions between contiguous   glucose units of the peracetylated cyclodextrin.

      Address (URL): http://www.science-direct.com/science/article/B6VMF-4VNK69J-1/2/876a65c9ec887531 f047107b267d45e6