Journal of Physical Chemistry A, Vol.111, No.45, 11524-11530, 2007
Electrolyte-concentration and ion-size dependence of excited-state intramolecular charge-transfer reaction in (alkylamino)benzonitriles: Time-resolved fluorescence emission studies
Time-resolved studies with three intramolecular charge-transfer molecules 4-(1-azetidinyl)benzonitrile (P4C), 4-(1-pyrrolidinyl)benzonitrile (P5C), and 4-(1-piperidinyl)benzonitrile (P6C) in ethyl acetate in presence of LiClO4 indicate that the average reaction time for LE -> CT conversion increases at low electrolyte concentration and then decreases to become comparable and even lower than that in the pure solvent. Except for Mg2+, the average reaction time decreases linearly with the ion size in perchlorate solutions of ethyl acetate. The observed electrolyte-concentration dependence of the average reaction time for these molecules agrees well with the predictions from the theory of Zwan and Hynes [Chem. Phys. 1991, 152, 169] in the broad barrier overdamped limit with barrier frequency, omega(b) approximate to 2 x 10(12) s(-1).