Amino-Functionalized Luminescent Metal–Organic Framework for Turn-On Detection of Al³⁺ Ions

Aluminum products have a wide range of applications in daily life, but excessive accumulation of aluminum (Al³⁺) ions causes diseases and affects human health. The accurate detection of Al³⁺ ions is crucial for preventing their accumulation and mitigating adverse effects on human health. Herein, a luminescent metal-organic framework (MOF), FJU-40-NH₂, has been designed for selective aluminum ion (Al³⁺) detection with a significantly enhanced fluorescence response. This designed FJU-40-NH₂ incorporates a π-conjugated aromatic system as luminescent units and abundant free amino groups as potential binding sites, endowing it with an exceptional ability to selectively sense Al³⁺ ions. This host-guest interaction results in a significant fluorescence enhancement, making the FJU-40-NH₂ an ideal "turn-on" sensor for Al³⁺ ions with high sensitivity, selectivity, and stability. This substantial fluorescence enhancement is due to the efficient electron transfer after the interaction between Al³⁺ ions and the amino groups of FJU-40-NH₂. More importantly, this "turn-on" fluorescent sensor has been successfully utilized for the analysis of Al³⁺ ion content in real food samples, yielding recoveries ranging from 92.2 to 105.0%, confirming its potential applications in practical environmental and food safety monitoring.