A single 2-(2'-hydroxyphenyl)benzothiazole derivative can achieve pure white-light emission.

The synthesis and photophysics of two novel 2-(2'-hydroxyphenyl)benzothiazole (HBT) derivatives are presented. The electron-withdrawing trifluoromethyl (CF3) group in compound 1 facilitates the deprotonation of the phenolic hydroxy group. Well-resolved triple fluorescence from the enol, keto, and phenolic anion, which ranges from 350 to 600 nm, was detected for 1 in ethanol, which marks the first time triple fluorescence from an excited-state intramolecular proton transfer (ESIPT) molecule has been reported. Both triphenylamine and CF3 were introduced into derivative 2. Intramolecular charge transfer and the "red-edge effect" resulted in the bathochromic shift of dual fluorescence of 2. Triple fluorescence was also observed for 2 in ethanol. In mixed acetonitrile and ethanol, pure white-light emission with CIE coordinates of (0.33, 0.33) and a quantum yield of 0.25 was achieved for 2. This work provides a new avenue for the rational design of an ESIPT molecule to achieve white-light generation under mild conditions.