In situ grown MOF/COF dual-emission composite as ratiometric fluorescence sensing platform for rapid detection of nitrofuran in foods

MOF/COF composites merge the properties of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), thus holding great promise for the dual-emission fluorescence sensing applications. In this work, COF TAPA-TFPB and NH 2 -MIL-53(Al) were integrated to form a MOF/COF TAPA-TFPB composite using a simple and safe room-temperature synthesis approach. The resulting composite not only mitigates the stringent synthesis conditions typically associated with COFs but also suppresses the aggregation-caused quenching (ACQ) effect of COFs, and effectively coordinates the fluorescence properties of both MOFs and COFs as well. The quenching of both emission peaks at 435 nm and 580 nm was observed as the analyte concentration increased. Based on this dual-response, a ratiometric probe was constructed using the intensity ratio I 435 /I 580 . The resulting ratiometric platform rapidly detects nitrofurans (NFs) within 5 min, shows a linear response from 0 to 100 μM with a detection limit of 0.057–0.102 μM. This work expands the synthetic approach to MOF/COF composites, facilitating their development as multi-emission sensors in detecting various pollutants.