A β-diketone main-chain polymer fluorescence sensor for rapid screening and quantitative fluorescent detection of aluminum in food products

Friedel–Crafts acylation yields β-diketone polymer superior to Claisen condensation. • The probe exhibits a vivid green-to-blue shift and intensity enhancement with Al 3+ . • Conformation restriction by Al 3+ coordination enables fluorescence change. • Dual-mode sensing enables both visual screening and precise quantification. • Results in wheat food samples show high consistency with standard ICP-MS methods. Aluminum additives in flour-based foods pose safety concerns and require rapid monitoring. This study presents a high-performance β-diketone main-chain polymer fluorescence sensor synthesized via Friedel–Crafts acylation for specific aluminum detection. This preparation method yielded a polymer with superior sponge-like porosity and extended π-conjugation. Upon Al 3+ coordination, the probe exhibits a distinct fluorescence transition from dim green to brilliant deep blue, enabling visual identification. The response follows a positive cooperative logistic model, achieving a limit of detection of 1.78 μmol/L. Mechanistic studies attribute signal enhancement to a synergistic effect, where coordination restricts the conformational relaxation of the polymer backbone to suppress non-radiative decay while simultaneously increasing radiative oscillator strength. Validated in wheat derivatives with a calibration strategy, the method achieved quantitative results consistent with inductively coupled plasma mass spectrometry. This work highlights the value of backbone-integrated recognition sites and conformational restriction for sensing. A β-diketone main-chain polymer fluorescence sensor addresses the challenge of monitoring aluminum in wheat-based foods. The probe exhibits a positive cooperative logistic response to Al 3+ , characterized by a vivid green-to-blue emission shift. By leveraging a coordination-induced restriction of main-chain conformational relaxation mechanism, the sensor achieves excellent selectivity and sensitivity, allowing for both naked-eye inspection and precise instrumental quantification in real samples. Download: Download high-res image (140KB) Download: Download full-size image