A galunamide derivative consisting of a fluorophore with benzoxazole and a cyano unit was designed and synthesized to realize a dual response to acid vapor and mechanical force. Photophysical properties and self-assembly were investigated. The dilute solution could respond to the acid stimulus, and the emission peak at 472 nm shifted to 535 nm with the addition of trifluoroacetic acid (TFA). Moreover, the derivative could self-assemble into thin nanofibers in its gel phase, and the fluorescence of the xerogel film is sensitive to TFA vapor. The emission color gradually changed from yellow to orange red upon exposure to acid vapor, and the detection limit is as low as 70 ppb for TFA. The solid exhibited a reversible fluorescence color change under the stimuli of mechanical force and solvent annealing. The UV-vis absorption and IR spectra indicate that the fluorescence color conversion can be attributed to the destruction of intermolecular hydrogen bonds and pristine π–π interaction induced by mechanical force.

中文翻译：

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荧光加仑酰胺衍生物的自组装以及对酸蒸汽和机械力刺激的检测

设计并合成了由荧光团与苯并恶唑和氰基单元组成的半乳糖酰胺衍生物，以实现对酸蒸汽和机械力的双重响应。研究了光物理性质和自组装。稀溶液可以响应酸刺激，加入三氟乙酸（TFA）后，在472 nm处的发射峰移至535 nm。此外，该衍生物可以在其凝胶相中自组装成细纳米纤维，并且干凝胶膜的荧光对TFA蒸气敏感。暴露于酸性蒸汽后，发射颜色从黄色逐渐变为橙红色，并且对于TFA的检测极限低至70 ppb。在机械力和溶剂退火的刺激下，固体表现出可逆的荧光颜色变化。