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Metal–organic frameworks (MOFs) have been extensively studied for enhancing the performances of fluorescent probes based on the host–guest chemistry, while the selectivity enhancement of fluorescent probes through integration into MOFs… Click to show full abstract
Metal–organic frameworks (MOFs) have been extensively studied for enhancing the performances of fluorescent probes based on the host–guest chemistry, while the selectivity enhancement of fluorescent probes through integration into MOFs is still relatively rare. In this work, Cd:ZnS QDs were integrated into ZIF-8 that could specifically interact with Cu2+ for fluorescence sensing. The fluorescence of Cd:ZnS QDs was quenched by Cu2+ based on cation exchange, while this phenomenon was also observed in the presence of Mn2+, Co2+ and Ni2+. By contrast, only Cu2+ induced the fluorescence quenching of Cd:ZnS QDs@ZIF-8 as a result of its specific interaction with ZIF-8. In addition, Cd:ZnS QDs@ZIF-8 displayed a fast response of 1 min and a low detection limit of 16 nM toward Cu2+, and moreover, it was successfully applied to detecting Cu2+ in water samples with spiked recoveries ranging from 90.1 to 109.8%. These results indicate that integration into ZIF-8 is an efficient strategy to enhance the selectivity of fluorescent probes toward Cu2+.