Solvent-induced changes in electronic structure of the exciplex between trans-9-styrylphenanthrene and diethylaniline

Abstract

The rate parameters for the formation, dissociation and deactivation of the exciplex between trans-9-styrylphenanthrene (t-9-StPh) and diethylaniline have been studied in various solvents. From Arrhenius plots for the rate constants, the enthalpy of formation (ΔH°) and entropy of formation (ΔS°) and the repulsion energy (ΔH_r) in the Franck-Condon ground state have been obtained. The decrease of the exciplex radiative rate parameter k_FE and of the formation enthalpy coupled with an increase of the exciplex. Moreover, in a solvent of medium polarity, the stability of the complex is javoured by a positive entropy change. ΔH° and ΔS° for the t-9-StPh exciplexes fit satisfactorily a linear compensation relationship described in the literature.