Dual-Emitting Dye@MOF Composite as a Self-Calibrating Sensor for 2,4,6-Trinitrophenol

An anionic metal-organic framework (MOF) {(NH₂Me₂)[Zn₃(μ₃-OH)(tpt)(TZB)₃](DMF)₁₂}_n (1, tpt = 2,4,6-tri(4-pyridyl)-1,3,5-triazine, H₂TZB = 4-(1H-tetrazol-5-yl)benzoic acid and DMF = N,N-dimethylformamide), with both nanosized cages and partitions, has been solvothermally synthesized, which can serve as a crystalline vessel to encapsulate the fluorescent dye rhodamine 6G (Rh6G) via a "bottle around ship" approach. As a result, the obtained dye@MOF composite system features a blue emission of the ligand at 373 nm and a red emission of Rh6G at 570 nm when dispersed in solution, which could be used for decoding the trace amount of 2,4,6-trinitrophenol (TNP) by referring the peak-height ratio of each emission, even in coexistence with other potentially competitive nitroaromatic analytes. Furthermore, the observed fluorescence responses of the composite toward TNP are highly stable and reversible after recycling experiments. To the best of our knowledge, this is the first example of an MOF-implicated self-calibrated sensor for TNP detection.