The host-guest inclusion complexes that comprise an inverted cucurbit[7]uril (iQ[7]) and a quinoline derivative, 4-(4-dimethylaminostyryl) quinoline (DSQ) at different pHs were exploited as multiple supramolecular sensors to sense l-α-amino acids. DSQ complexation inside iQ[7] at different pHs leads to increased fluorescence and formation of different-colored iQ[7]-DSQ complexes. The enhanced fluorescence of DSQ after iQ[7] encapsulation may be attributed to limited dimethylamine rotation and the formation of a twisted internal charge transfer (TICT) state. The DSQ@iQ[7] sensors have different affinities for l-α-amino acids at different pHs. Therefore, we propose a pH-stimulus response supramolecular sensor for the discrimination of structurally similar l-α-amino acids in aqueous solution.

中文翻译：

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水溶液中氨基酸的 pH 刺激响应染料-葫芦脲传感器。

包含倒葫芦 [7] 脲 (iQ[7]) 和喹啉衍生物 4-(4-二甲基氨基苯乙烯基) 喹啉 (DSQ) 在不同 pH 值下的主客体包合物被用作多个超分子传感器来感知 l- α-氨基酸。在不同 pH 值下 iQ[7] 内部的 DSQ 络合导致荧光增加并形成不同颜色的 iQ[7]-DSQ 复合物。iQ[7] 封装后 DSQ 的荧光增强可能归因于有限的二甲胺旋转和扭曲的内部电荷转移 (TICT) 状态的形成。DSQ@iQ[7] 传感器在不同的 pH 值下对 l-α-氨基酸具有不同的亲和力。因此，我们提出了一种 pH 刺激响应超分子传感器，用于区分水溶液中结构相似的 l-α-氨基酸。