Multi Stimuli Responsive Non-Doped Red Emitting AIEE Active Phenothiazine-Based Chalcones: Crystal Structure, Solvatochromism, Turn-on Mechanofluorochromism and Acidochromism

We report on a series of phenothiazine-based D-pi-A-pi-D type cross-conjugated non-doped red-emitting molecules synthesized by simple Claisen-Schmidt condensation, which exhibit excellent AIEE phenomena through the formation of large-sized nano-aggregates. These thermally stable red fluorescent organic materials have low band gap energies (E-g=1.84-2.15 eV) and also display reversible mechanofluorochromism. The CIE chromaticity coordinates of red emissive ground powders were closer to the standard red-light chromaticity coordinates. These chalcones also exhibited positive solvatochromism, and large Stokes shifts. Finally, these compounds were utilized as reversible volatile acid sensors to detect TFA in solution as well as in solid state, by virtue of the presence of electron withdrawing carbonyl oxygen, and they could detect TFA at a concentration as low as 15.8 ppm in the presence of C4.