Benzo[a]Phenoxazine Derivatives as Fluorescent Disperse Dyes—Spectroscopic Characterization and Application

The number of disperse dyes other than azo dyes commercially available is limited. Similarly, red and orange fluorescent disperse dyes are limited to coumarins (e.g., Disperse Red 277 and 374), thioindigo (Disperse Red 364), and naphthalimide (C.I. Disperse Orange 32). Here, we used benzo[a]phenoxazine derivatives as disperse dyes to obtain red and orange fluorescent polyester fabrics. The 6-substituted position derivatives of 9-nitro- and 9-amino-5H-benzo[a]phenoxazin-5-one were synthesized and applied to polyester at a 1% depth using a high-temperature pressure technique. The photochemical stability of benzo[a]phenoxazine derivatives was investigated in acetonitrile solution. The lowest photostability in acetonitrile is observed for the 9-nitro-5H-benzo[a]phenoxazin-5-one (2a). Similarly, dye 2a has the lowest lightfastness, while the remaining dyes exhibit 3/4 stability on polyester. The chromaticity coordinates and luminance coefficient β values were measured before and after photofading. All fabrics dyed with benzophenoxazine dyes have fluorescence quantum yields above 20%. The investigated fabrics exhibit strong resistance to sublimation (4/5), washing (4/5), and rubbing (4/5).