Two new Cd-based metal-organic frameworks for afterglow detection of Fe³⁺ and NH₃

Luminescent metal-organic frameworks (LMOFs) have been extensively employed as detection probes. However, the majority of the reported probes are fluorescence-based, lacking reports on visible afterglow detection. Herein, we present two new afterglow MOFs, compound 1 with a layered structure and 2 with an interpenetrated dia framework. 1 exhibits blue-green room temperature phosphorescence (RTP) (tau(485nm) = 264.6 ms) and can serve as an afterglow "turn off" probe for selective detection of Fe3+ ions through a framework decomposition mechanism, with a detection limit of 1.63 mu M. Displaying blue-green RTP (tau(495nm) = 83.0 mu s), 2 can serve as an afterglow "turn on" probe for the detection of NH3 in both solution and vapor phases. Notably, the afterglow of 2 is visually activated even at concentrations of NH3 vapor as low as 6 ppm. Mechanistic investigations reveal that the "turn on" response is attributed to structural transformation induced by NH3 molecules replacing coordinated solvents. Furthermore, their potential applications were demonstrated through the development of portable test strips for detecting Fe3+ ions and an cryptographic algorithm logic gate for NH3 deciphering. This work opens up new opportunities for the development of LMOF-based afterglow probes.