Influence of lithium perchlorate on electron transfer processes occurring in bianthryl in 2-methyltetrahydrofuran

Influence of lithium perchlorate on the charge transfer fluorescence of bia nthryl (BA) in 2-methyltetrahydrofuran (MTHF) has been investigated at thre e temperatures (263, 283 and 313 K). Analysis of the band shapes of the CT emission has been performed using Could and Farid procedure for the electro n transfer radiative process with three optimization parameters, namely the internal reorganization energy (lambda(v)), the external reorganization en ergy (lambda(s)), and the free enthalpy of back electron transfer process ( Delta G). It has been shown that the external reorganization energy and the free enthalpy (Delta G) increase with the increasing salt concentration an d saturate at higher salt concentrations whereas the internal reorganizatio n energy does not depend on temperature and salt concentration. This effect is due to increasing medium polarity caused by the addition of the salt mo lecules having a large dipole moment. The changes of the external reorganiz ation energy are quite satisfactorily described by the Marcus equation for lambda(s). The changes of free enthalpy follow the relation derived by Well er. (C) 1999 Elsevier Science B.V. All rights reserved.