The Synthesis Use of a Difluorinated Amino‐Benzo‐Cinnoline Dyes (ABCDyes) Enables Fine Tuning of Emission Through Double SNAr Late‐Stage Functionalization

In this work, we report the synthesis of a difluorinated derivative of amino‐benzo‐cinnoline dyes (ABCDyes) designed for late‐stage functionalization via double SNAr reactions with dinucleophilic species, enabling rapid access to structurally diverse fluorophores. This strategy led to the development of tetrahydroquinoxaline (THQ) and tetrahydrobenzodiazepine (THB) derivatives exhibiting markedly redshifted emission, thereby significantly extending the spectral coverage of the ABCDye family. A comprehensive photophysical characterization of these previously unexplored fluorophores reveals pronounced solvatochromism and an unconventional fluorescence behavior, with emission efficiencies enhanced in polar media. Selected optical properties were rationalized through density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations. Finally, two of the newly developed dyes demonstrated efficient cellular internalization and were successfully applied to live‐cell fluorescence imaging, highlighting their potential for bioimaging applications.