Acid‐Responsive Absorption and Emission of 5‐<i>N</i>‐Arylaminothiazoles: Emission of White Light from a Single Fluorescent Dye and a Lewis Acid

Abstract

Abstract Solutions of 5‐ N ‐arylaminothiazoles containing pyridyl groups exhibited clear halochromism and halofluorism upon addition of Brønsted and Lewis acids. The addition of triflic acid to solutions of 5‐ N ‐arylaminothiazoles in Et 2 O induced bathochromic shifts of the absorption and emission bands. DFT calculations suggested that the spectral changes arise from the protonation of the pyridyl group of the thiazoles in Et 2 O. Single‐crystal X‐ray diffraction analysis of a thiazole and its protonated form revealed the change of the conformation around the thiazole ring. The emission of white light was accomplished from a single fluorescent dye by adjusting the ratio of dye and B(C 6 F 5 ) 3 , whereby the International Commission on Illumination coordinates showed a linear change from blue to orange.