Dye@MOF composites (RhB@1): Highly sensitive dual emission sensor for the detection of pesticides, Fe3+ and ascorbate acid

With the rapid development of economy, industrial and agricultural pollutants have caused great damage to the ecological environment and the normal development of organisms, posing a serious threat to global public health. Therefore, rapid and sensitive detection of pollutants is very important for environmental safety and people's health. A stable multi-response fluorescence sensor (RhB@1) with dual emission characteristics was constructed by embedding RhB guest molecules in Zn-MOF using a simple one-pot method. XRD, IR, XPS, Raman and other characterization methods were used to demonstrate the formation of composite materials. The sensor has two fluorescence emission peaks at 415 nm and 575 nm under the excitation of 316 nm. It has high sensitivity and low detection limit (7.94 and 7.82 nmol/L, respectively) in the detection of fluazinam (FLU) and Fe3+. The mechanism of fluorescence quenching may be due to the synergistic effect of IFE and PET. Outstandingly, when ascorbate acid (AA) was added to the quenching system of Fe3+ and RhB@1, its fluorescence gradually recovered, forming the unique “on-off-on” sensor. Therefore, RhB@1 has a fast fluorescence response and good stability, making it potentially useful in practical application and biosensors. More significantly, using Fe3+ and AA as chemical input signals, a binary intelligent logic gate device has been developed based on the “on-off-on” response mode of RhB@1, which extends the application of logic gate switching devices in the chemical field. In addition, a visual portable test paper with good selectivity and high sensitivity was developed, which can be used for rapid detection of FLU, showing its broad application prospect.