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

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 Al3+ 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.