Aluminum is a widely distributed element with potential harm to human health, and the analysis of phenylpyruvic acid (PPA) is also routine in clinical uroscopy for metabolic disorders. In this work, we synthesized a UiO-66-backboned MOF, UiO-66-(OH)₂, to construct an “off–on–off” platform for the sequential fluorescence detection of Al³⁺ and PPA. With incorporated hydroxyl groups, this MOF could capture Al³⁺ ions in aqueous solution and show enhanced fluorescence response through an excited-state intramolecular proton transfer mechanism. The binding affinity of PPA to Al³⁺ is stronger than that to the MOF; therefore, the further addition of this compound to UiO-66-(OH)₂–Al³⁺ extracts the adsorbed Al³⁺ and restores the original weak emission of the MOF. UiO-66-(OH)₂ exhibited good selectivity and sensitivity (DL = 47 nM for Al³⁺ and 100 nM for PPA) in both steps of detection and was successfully applied to the analysis of PPA in artificial urine.

中文翻译：

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发光MOF作为荧光传感器，用于顺序检测Al ³⁺和苯丙酮酸†

铝是一种广泛分布的元素，对人体健康有潜在的危害，苯丙酮酸（PPA）的分析在代谢性疾病的临床尿道镜检查中也是常规操作。在这项工作中，我们合成了UiO-66骨架的MOF UiO-66-（OH）₂，构建了一个“ off-on-off”平台，用于顺序检测Al ³⁺和PPA的荧光。通过结合羟基，该MOF可以捕获水溶液中的Al ³⁺离子，并通过激发态分子内质子转移机制显示出增强的荧光响应。PPA对Al ³⁺的结合亲和力强于MOF。因此，将该化合物进一步添加到UiO-66-（OH）₂ -Al ³⁺提取吸附的Al ³⁺并恢复MOF的原始弱发射。UiO-66-（OH）₂在两个检测步骤中均显示出良好的选择性和灵敏度（对于Al ³⁺，DL = 47 nM，对于PPA为100 nM），已成功地应用于人造尿液中PPA的分析。