Aggregation-induced Emission Properties of 2-(<i>N,N</i>-diphenylamino)tryptanthrin

Abstract

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.

Solid-State Fluorescence of Tryptanthrin Analogs

“…We previously explored the photophysical properties of tryptanthrin derivatives used as novel fluorescent dyes [1][2][3][4][5][6][7][8]. Tryptanthrin (T, Fig.…”

Photophysical Properties of 2-Hydroxytryptanthrin Analog as a Near-Infrared Dye for Fluorescent Imaging

“…Fluorescent analysis reagents such as fluorescent chemosensors and fluorescent probes that are based on organic fluorescent dyes are simple and highly versatile and in particular, they have become indispensable as molecular tools for understanding biological phenomena in life sciences [1,2]. We have been exploring the photophysical properties of tryptanthrin derivatives as novel fluorescent dyes [3][4][5][6][7][8][9][10]. Tryptanthrin (T, Fig.…”

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

“…Nevertheless, in high concentration solutions, the rotational movement of the phenyl group is suppressed, favoring a light-emitting radiative process that leads to the emission of fluorescence. The introduction of an electron-donating group at the 2-position of tryptanthrin 6,7) , an antimicrobial substance extracted from plants like indigo, is known to result in outstanding fluorescent properties [8][9][10][11][12][13][14][15][16][17][18][19][20] . However, in highly concentrated solutions, π-π stacking interactions in fluorescent tryptanthrin compounds with planar structures cause fluorescence quenching.…”