A lanthanide-based hydrogen-bonded organic framework for real-time visual and ratiometric fluorescence monitoring of histamine in seafood

The smart design of luminescent hydrogen-bonded organic frameworks (HOFs) as multi-functional optical sensors is of great significance for the development of advanced materials. In this context, we designed and synthesized a fluorescence probe (Eu-HOF/DPA) with the characteristics of dual emissions at 452 nm and 616 nm. The histamine introduction increased the system pH, enhancing the energy transfer efficiency from pH-sensitive antenna ligand DPA to Eu 3+ . This resulted in an intensified emission of Eu 3+ at 616 nm while the emission from ligand at 452 nm remained constant, enabling ratiometric fluorescence sensing and visual detection for histamine. Furthermore, a composite membrane was fabricated by embedding the probe onto a flexible substrate, which can be integrated with a smartphone for real-time monitoring the freshness of shrimp and crabs.