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-cy clodextrin (beta-CD) and three electronic states of 4-(N,N-dimethylami no)benzonitrile (DMABN), namely the ground state S0, the Franck-Condon excited state B and the charge transfer state A*, is found. The comp lexation reaction involving the B state is exothermic, while the comp lexation of the A state is entropy driven, indicating different mecha nisms. Evidence is presented to suggest that B and A* occupy differen t microenvironments within the CD. A 1:1 stoichiometry is confirmed fo r the three reactions. Values of DELTAH-0 and DELTAS0 are derived from the temperature dependence of the equilibrium constants.