Aggregation-induced Emission and Solid-State Fluorescence of 2-(4-(N,N-diphenylamino)phenyl)tryptanthrin

Abstract

2-(4-(N,N-diphenylamino)phenyl)tryptanthrin (T2PhNPh₂) was synthesized and its photophysical properties were examined. Among the seven examined solvents of various polarities, T2PhNPh₂, which is non-planar only showed weak red fluorescence in non-polar toluene and 1,4-dioxane. This was assumed to be due to thermal deactivation as a result of the rotation of the phenyl groups’ stimulation of internal conversion in calculation using the density functional theory. Although T2PhNPh₂ was non-fluorescent in tetrahydrofuran (THF), aggregation-induced emission was shown to cause fluorescence in water/THF solutions with more than 65 vol% water content. Additionally, fluorescence was observed at ca. 650 nm in the solid state.