CONTRIBUTIONS OF ELECTROSTATIC AND HYDROPHOBIC INTERACTIONS TO THE HOST GUEST COMPLEXATION OF PYROCATECHOLATE ANIONS WITH CATIONIC CYCLODEXTRINS

Binding constants of a series of 4-substituted pyrocatechols (1,2-dihydroxybenzenes) to four 6-deoxy, 6-amino derivatives of beta-cyclodextrin have been determined from the kinetics of their autooxidation at pH 10.0. In several cases, the binding constants at pH 6.0 have been determined by spectrophotometry. Cationic forms of amino derivatives of beta-cyclodextrin bind pyrocatecholate anions with equilibrium constants up to 10(5) dm3 mol-1. The electrostatic and hydrophobic interactions were shown to contribute additively to the free energy of the host-guest complexation.