The interaction between peracetylated beta-cyclodextrin and several triphenyl phosphine derivatives was studied in supercritical carbon dioxide (scCO2) by UV-visible spectroscopy. The equilibrium constant for a 1:1 complexation reaction was obtained from titration spectra and calculated using two established mathematical models. The values of the equilibrium constants are 1-3 orders of magnitude smaller than those obtained inaqueous solution with analogous phosphines. This is likely due to the absence in scCO2 of the hydrophobic effect, which is replaced by a corresponding, but weaker, CO2-phobic effect. The largest value of Kf wasfound for complexes of diphenyl(4-adamantylphenyl)phosphine, which is rationalized on the basis of theexcellent fit of the phosphine in the cyclodextrin cavity, leading to enhanced host-guest van der Waals interactions. This study can be considered the first step toward the comprehension of the complexationthermodynamics of modified cyclodextrins soluble in scCO2.
|Rivista||JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL|
|Stato di pubblicazione||Published - 2007|
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry