Room-Temperature Aqueous Synthesis of Amino-Functionalized Al-Based MOF as a Ratiometric Fluorescent Probe for Aqueous Dichromate Detection.

In this work, amino-functionalized Al-based MOF Al-GM was fabricated via a mild room-temperature aqueous route, which was applied as a ratiometric fluorescent probe for the specific detection of Cr2O72- in water. Characterizations including XRD, FT-IR, SEM, and BET verify that Al-GM synthesized in pure water exhibits high crystallinity and abundant mesoporous channels, with fully exposed amino recognition sites on the framework, delivering dual fluorescence emission signals. Sensing performance experiments demonstrate outstanding selectivity toward Cr2O72- with negligible interference from coexisting metal ions. Fluorescence titration reveals a wide linear detection range and an ultralow limit of detection, which is far lower than the discharge standard of Cr(VI) for industrial wastewater. pH-dependent tests confirm the stable sensing performance of the probe in water at a pH range of 5-9. XRD and FTIR spectra before and after Cr2O72- adsorption confirm intact crystal and organic coordination frameworks during ion recognition. Cr2O72- anions are selectively captured by the synergy of electrostatic attraction and intermolecular hydrogen bonds with amino sites. This study proposes a mild, organic-solvent-free synthetic strategy for MOFs, and the prepared Al-GM displays promising application potential for trace Cr(VI) monitoring in aquatic environments.