Supramolecular chemistry of Cyclodextrins in supercritical carbon dioxide: Spectroscopic Investigations

Abstract

Considering the high solubility of peracetylated-β-cyclodextrin (perAc-β-CD) in supercritical carbon dioxide (scCO2), it presents a means to increase the solubility of organometallic catalysts via the formation of inclusion complexes. The supramolecular chemistry of perAc-β-CD as a host for triphenyphosphine derivatives has been studied in scCO2 using UV absorption spectroscopy. It was found that the inclusion constant at 40 °C and 30 MPa is 10 to 1000 times smaller compared to analogous systems in aqueous solvent. Methanol is added to the scCO2 as a cosolvent to exploit the tunability of the supercritical phase and access a range of solvent polarities by varying the temperature, pressure, and fraction of methanol. This study is pursued with the goal of reaching a better comphension of the main factors affecting the phosphine–perAc-β-CD complexation to define rationale criteria for the design of phosphine ligands with high complexation constants suitable as supramolecular ligands for homogeneous catalysis in scCO2.

5th International Symposium on High Pressure Processes Technology and Chemical Engineering, June 2007, Segovia, Spain