PHOTOPHYSICS OF A NOVEL BICHROMOPHORIC MOLECULE - LOROMETHYLENO)-(9'H)-10,10'-DIHYDRO-9,9'-BIANTHRYL

The absorption and fluorescence of loromethyleno)-(9'H)-10,10'-dihydro -9,9'-bianthryl (CDDB) and its photophysics in a number of solvents ha ve been studied. In polar solvents CDDB gives enormous Stokes' shift a nd dual fluorescence from two different excited states namely R state and P state. The formation of a TICT (twisted intramolecular charge tr ansfer) state is confirmed from the measurements of excited state dipo le moments, lifetimes and deactivation pathways. The equilibrium betwe en R and P states has also been determined. To explain the enormous St okes' shift, photoisomerization of CDDB is considered as an alternate model other than TICT model. Benzene forms charge transfer complex wit h CDDB in the ground state, whereas in the excited state, this interac tion is enhanced.