Experimental evaluation of (LE) and (TICT) states dipole moments of 9,9 '-Bianthryl, 10-Bromo-9,9 '-Bianthryl and 10-Cyano-9,9 '-Bianthryl.

A comparative study on the solvation induced intramolecular charge transfer in the excited state has been made for 9,9'-Bianthryl (BA), 10-Bromo-9,9'- Bianthryl (BABr) and 10-Cyano-9,9'-Bianthryl (BACN) by fluorescence measure ment at room temperature. The study of this fluorescence in liquid solution s shows a strong dependence bf Stokes shift versus the dipole moment of the solvents. Experimental results show an important dipole moment variation b etween ground and TICT (Twisted Intramolecular Charge Transfer) states, whe reas this variation between ground and LE (locally excited) states is very weak, when the hydrogen atom in position 10 of (BA) is substituted by a bro mine or cyano group respectively. (C) 2000 Elsevier Science B.V. All rights reserved.