A simple terephthalaldehyde-based AIE fluorescent probe for highly sensitive and selective detection of bisulphites in food samples

A terephthalaldehyde-based AIE fluorescent probe has been widely used in bioimaging and sensor technology. But most of them have complex structures and are difficult to synthesize. In our experiments, an ethyl butyrate side chain was introduced on the benzene ring of terephthalaldehyde, diethyl 4,4′-((2,5-diformyl-1,4-phenylene)bis(oxy))dibutyrate (FPB), which enhances its Aggregation-Induced Emission (AIE) properties. This enhancement is attributed to the intermolecular hydrogen bond interaction. These findings are corroborated by results from X-ray single crystal diffraction. Meanwhile, it is well known that the aldehyde group and bisulfite (HSO₃⁻) exhibit a specific reaction through nucleophilic addition. We found that the product formed can disrupt intermolecular hydrogen bonding, thereby affecting the AIE properties. Based on the reaction of HSO₃⁻ and the aldehyde groups of FPB, the AIE fluorescent molecule (FPB) can be used to rapidly detect sulfur dioxide. Under the optimized experimental conditions, FPB shows high selectivity and anti-interference to HSO₃⁻ and fast response (less than 1 minute). The detection limit of bisulfite is 24.4 nM. Finally, FPB molecule was used to detect HSO₃⁻ in some vegetables purchased from local supermarkets and some dried fruits purchased online. The measurement results were compared with the test results of China's national standard method (GB 5009.34-2022). The data measured by FPB showed good consistency with the results measured by the national standard method.