Expanding the fluorescent window of nitro-substituted Triphenylamines through combined steric and electronic engineering
Journal
Journal of the Chinese Chemical Society
ISSN
0009-4536
2192-6549
Date Issued
2025-08-26
Author(s)
Abstract
The fluorescence of nitroaromatic fluorophores is highly sensitive to their environment and often exhibits a narrow “fluorescent window” in both solution and solid states. This limitation arises from the various fluorescence-quenching pathways, including S1 → Tn intersystem crossing (ISC), formation of a twisted intramolecular charge transfer (TICT) state, and antiparallel molecular stacking. Here, we report a series of nitro-substituted triphenylamines (nitro-TPAs), in particular the pentiptycene-derived nitro-TPAs PX series, to investigate whether combined steric and electronic engineering can broaden the fluorescent window across a wide polarity range and in the solid state. While substituent electronic effects tune the push-pull character, the bulky pentiptycene scaffold shields the nitrogen center from solvation and suppresses intermolecular stacking in the solid phase. Notably, the isocyanide derivative PNC exhibits fluorescence in all six tested solvents, n-hexane, toluene, dichloromethane, N,N-dimethylformamide, and acetonitrile, as well as in both crystalline and powdered forms. This work demonstrates the effectiveness of integrating steric and electronic strategies to expand the fluorescence window of flexible nitroaromatic systems.
Subjects
fluorescence
nitroaromatics
pentiptycene
triphenylamine
twisted intramolecular charge transfer (TICT)
SDGs
Publisher
Wiley
Type
journal article