Push–Pull Phenazine Fluorophores: Substituent‐Position Effects on Emission and Intermolecular Organization Modulated by Hydrogen Bonding and Molecular Symmetry

Phenazines have attracted considerable interest due to their distinctive redox and photophysical properties. However, systematic structure–property relationships for directly core‐substituted phenazines as tunable fluorophores remain underexplored. In this study, a series of push–pull sulfonylaminophenazine fluorophores are prepared from p‐phenylenediamine‐derived sulfonylanilines via one‐step oxidative annulation, and the effects of substituent position on their photophysical and solid‐state properties are systematically compared. The resulting dyes exhibit enhanced absorptivity, green‐to‐red emission with a modest dependence on solvent polarity, and minimal concentration quenching, together with moderate‐to‐large Stokes shifts and high photostability. Theoretical calculations and single‐crystal structural analyses reveal that push–pull substitution activates fluorescence by converting the lowest excited state from predominantly n,π* to emissive π,π*. The Etter‐rule‐directed hydrogen‐bonding patterns reinforce the push–pull character to modulate the emission wavelength, while also influencing, together with the molecular symmetry, the quantum efficiency and solubility. These results reveal substituent‐position‐dependent structure–property relationships within this push–pull phenazine family and highlight the phenazine scaffold as a promising platform for fluorophore development.