A STUDY OF THE INCLUSION COMPLEXES OF BETA-CYCLODEXTRIN WITH 3 ELECTRONIC STATES OF 4-(N,N-DIMETHYLAMINO)BENZONITRILE

A marked difference among the inclusion formation constants of beta-cyclodextrin (beta-CD) and three electronic states of 4-(N,N-dimethylamino)benzonitrile (DMABN), namely the ground state S0, the Franck-Condon excited state B* and the charge transfer state A*, is found. The complexation reaction involving the B* state is exothermic, while the complexation of the A* state is entropy driven, indicating different mechanisms. Evidence is presented to suggest that B* and A* occupy different microenvironments within the CD. A 1:1 stoichiometry is confirmed for the three reactions. Values of DELTAH-0 and DELTAS0 are derived from the temperature dependence of the equilibrium constants.