Achieving stimulus-responsive multicolor solid-state photoluminescence based on a single fluorescence compound has potential applications in anti-counterfeiting labels and visual detection. However, few such organic chromophores have these features and been used in this fields. In this study, multiple pH-sensitive sites were incorporated into a single molecule of succinimide substituted 2-(2′-hydroxyphenyl)Benzothiazole derivative () that was Aggregation induced emission (AIE) and Excited state intramolecular proton transfer (ESIPT) active, exhibiting multilevel and highly secured anti-counterfeiting abilities. Under ammonia atmosphere, exhibits reversible switching between the green and blue fluorescence. By rationally manipulating two stimuli (acid and base), labels incredibly shows four different emission colors. The multicolor fluorescence changes are irreversible and evidently depend on the order of acid-base added. Together with smartphone that can quickly and accurately identify the multiple colors, affords a new covert fluorescent anti-counterfeiting technique with high security through the combination of reversible and irreversible fluorescence multicolor changes, as well as order and stimuli-dependent luminescent patterns. In addition, labels are successfully applied for real-time and visual monitoring the food freshness of pork and shrimp. The molecular design rationale presented here provide a new design strategy for the purposes of multicolor anti-counterfeiting and food freshness detection.

中文翻译：

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具有聚集诱导发射和可调谐固态多色荧光的 pH 敏感 ESIPT 分子，用于防伪和食品新鲜度检测

基于单一荧光化合物实现刺激响应的多色固态光致发光在防伪标签和视觉检测方面具有潜在的应用。然而，很少有有机发色团具有这些特性并被用于该领域。在这项研究中，多个pH敏感位点被整合到琥珀酰亚胺取代的2-(2'-羟苯基)苯并噻唑衍生物()的单分子中，该衍生物具有聚集诱导发射(AIE)和激发态分子内质子转移(ESIPT)活性，表现出多层次、高度安全的防伪能力。在氨气氛下，表现出绿色和蓝色荧光之间的可逆转换。通过合理地操纵两种刺激（酸和碱），标签令人难以置信地显示出四种不同的发射颜色。多色荧光变化是不可逆的，并且显然取决于酸碱添加的顺序。与可快速准确识别多种颜色的智能手机相结合，通过可逆和不可逆荧光多色变化以及顺序和刺激依赖性发光图案的结合，提供了一种安全性高的新型隐蔽荧光防伪技术。此外，还成功应用标签对猪肉、虾等食品新鲜度进行实时、可视化监控。这里提出的分子设计原理为多色防伪和食品新鲜度检测提供了一种新的设计策略。