Photochromic 5-phenylpyrazolidin-3-one-based azomethine imines containing 2-((1H-imidazol-2-yl)methylene) 1, 2-(pyridin-2-ylmethylene) 2, 2-(quinolin-2-ylmethylene) 3, and 2-((8-hydroxyquinolin-2-yl)methylene) 4 substituents were synthesized. All the compounds exist in the ring-opened O forms. Under irradiation with light of 365 nm, compounds 1–4 undergo thermally reversible isomerization into ring-closed bicyclic diaziridine isomers C. Azomethine imines 1–3 exhibit properties of ion-active molecular “off-on” switches of fluorescence when interacting with F− or AcO− anions. Compound 4 represents a bifunctional chemosensor demonstrating a colorimetric “naked-eye” effect for Ni2+ cation and complete fluorescence quenching in the presence of H+, F−, and CN− ions.

中文翻译：

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5-Phenylpyrazolidin-3-one Azomethine亚胺的合成及光致变色和光谱发光特性

含有 2-((1H-imidazol-2-yl)methylene) 1, 2-(pyridin-2-ylmethylene) 2, 2-(quinolin-2-ylmethylene) 3 的光致变色 5-phenylpyrazolidin-3-one-based azomethine 亚胺, 和 2-((8-羟基喹啉-2-基) 亚甲基) 4 个取代基被合成。所有化合物均以开环O形式存在。在 365 nm 光的照射下，化合物 1-4 发生热可逆异构化成闭环双环二氮丙啶异构体 C。偶氮甲碱亚胺 1-3 在与 F− 相互作用时表现出离子活性分子“开-关”荧光开关的特性或 AcO− 阴离子。化合物 4 是一种双功能化学传感器，展示了 Ni2+ 阳离子的比色“裸眼”效应，并在 H+、F- 和 CN- 离子存在下完全荧光猝灭。