A simple strategy for constructing acylhydrazone photochromic system with visible color/emission change and its application in photo-patterning

ABSTRACT As a potential photochromic system, acylhydrazones exhibit many outstanding advantages including low cost, simple synthesis and high modifiability compared with some classic photochromic systems. However, the absorption wavelengths of acylhydrazones usually locate in ultraviolet region, which makes the band separation between the absorbance maxima of its irradiated and unirradiated forms cannot be observed by naked eyes and greatly limits their practical applications. In this work, a simple strategy for constructing acylhydrazone photochromic system with visible color/emission change is provided. Rhodamine 6 G hydrazine-2-aldehyde-pyridine Schiff base (compound 3) is designed and synthesized by combining acylhydrazone with Rhodamine 6 G structure. The introduction of Rhodamine 6 G moiety to 3 not only makes it remain all the advantages of acylhydrazone photochromic system but also exhibits visible photo-induced color/emission changes both in solution and in a solid matrix. Moreover, 3 exhibits reversible photochromic property with good fatigue resistance, which makes it an excellent candidate for photo-patterning.