High-Performance Near-Infrared Chlorinated Rylenecarboximide Fluorophores via Consecutive C-N and C-C Bond Formation

A new class of near-infrared (NIR) fluorophores, PAI, is obtained by consecutive C-N/C-C bond formation between diphenylamines and 9,10-dibromoperylenecarboximide. Owing to the rigid structure, extended pi-conjugation and pronounced push-pull substitution, these fluorophores show emission maxima up to 804nm and large Stokes shifts. The extraordinarily high fluorescence quantum yields from 47% to 70% are attributed to chloro substitution in the bay positions of the perylene core. These characteristics, together with high photostability, qualify them as useful NIR emitters for applications as biomarkers and security inks.