Solvent-dependent dual emission processes in charge-transfer excited states of phenothiazine-triphenyltriazine conformers

Abstract

We have investigated the solvent effects on charge-transfer excited states in a donor-acceptor type luminescent material, phenothiazine-triphenyltriazine (PTZ-TRZ), which has characteristic two conformers: quasi-axial and quasi-equatorial conformers. Solvent permittivity dependence of steady-state photoluminescence spectra using mixture solvents of toluene and tetrahydrofuran (THF) indicated that the two conformers have almost the same excited-state dipole moments. Time-resolved photoluminescence and transient absorption spectra in toluene and THF showed a different solvent dependence between the two conformers. From the detailed analysis of these time-resolved spectra, we revealed the solvent-dependent emission processes in the two conformers.