Highly visible bis-heterocyclic acridinium and xanthenium-based dyes: Synthesis, AIEE, and modacrylic dyeing

A series of highly visible new bis-heterocyclic acridinium and xanthenium-based dyes were synthesized and were characterized with 1H, 13C NMR, and HRMS spectra. These dyes showed excellent molar attenuation coefficient and fluorescence quantum yield. All the acridinium and xanthenium-based compounds were aggregation-induced enhanced emission (AIEE) active fluorophores. The restriction in rotation of the free rotary aryl group at the 9th position of acridinium and xanthenium-based compounds was one of the reasons for the AIEE activity. This phenomenon was supported by viscochromic studies. The compounds showed excellent fluorescence in varied pH that expands the scope of its usage in biological imaging. With commendable color brightness, molar absorptivity, reflectance, and emission, they were used in high visible modacrylic fabric dyeing for protective wear. The dyed fabrics were investigated for color coordinates and color strengths. The dyeing studies were compared with acridine orange and rhodamine B commercial standards. The lightfastness of compounds 3e and 4e were investigated with respect to commercial acridine orange and rhodamine B.