Excited-state Relaxation Processes of Three Newly Synthesized Multi-Branched Alkyl-Triphenylamine End-Capped Triazines

The excited-state relaxation processes of three newly synthesized multi-branched alkyl-triphenylamine end-capped triazines ATT-(1–3) are characterized in different solvents by steady-state and time-resolved spectroscopy. In toluene, a weakly polar solvent, the emission originates from the intramolecular charge transfer (ICT) state; in tetrahydrofuran (THF), a strongly polar solvent, the existence of a nonradiative channel from ICT to twisted intramolecular charge transfer (TICT) accelerates the relaxation rate of the ICT state. The rate of the evolution process of ATT-(1–3) increases with increasing number of donor branches, which could ascribed to enhancements in the electron donor and acceptor abilities of the triazines.