Aggregation-induced Emission Properties of 2-(N,N-diphenylamino)tryptanthrin

抄録

We previously reported that 2-aminotryptanthrin (T2NH₂) and 2-(N,N-dimethylamino)tryptanthrin (T2NMe₂) possess excellent photophysical properties such as wide-wavelength absorption and emission in the visible region and a high fluorescence quantum yield. These compounds also exhibit large positive fluorescent solvatochromism. In this study, the new derivative 2-(N,N-diphenylamino)tryptanthrin (T2NPh₂) is synthesized, and its photophysical properties are investigated. In contrast to T2NH₂ and T2NMe₂, T2NPhe₂ shows weak fluorescence only in nonpolar toluene and 1,4-dioxane among the 13 solvents of different polarity tested, which is considered to be due to thermal deactivation resulting from the promotion of internal conversion by the rotation of the phenyl groups. Although T2NPhe₂ is nonfluorescent in tetrahydrofuran (THF), fluorescence is observed in water/THF solutions with more than 80 vol% water content as a result of aggregation-induced emission.