Fast, highly selective and sensitive anionic metal-organic framework with nitrogen-rich sites fluorescent chemosensor for nitro explosives detection.

Developing a highly efficient fluorescent sensor for detection of trace amounts of nitro explosives remains a great challenge. Porous metal-organic frameworks (MOFs) are one class of promising fluorescent sensors towards small molecules. Herein, we constructed an anionic Zn-based MOF FJI-C8 based on π-conjugated aromatic ligand H6 TDPAT (2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) containing nitrogen-rich sites. On account of the high density of uncoordinated N atoms, the high overlap between the emission spectrum of the anionic MOF FJI-C8 and the UV-vis absorption spectrum of the representative nitro explosive 2,4-dinitrophenol (2,4-DNP), and the porosity of the MOF, FJI-C8 is demonstrated to be an excellent chemosensor for 2,4-DNP with fast response time (less than 30s), high selectivity (Ksv =5.11×104 M-1 for 2,4-DNP), extra sensitivity (LOD=0.002866mM for 2,4-DNP), low usage amount (0.04mg/mL), good stability and quantitative detection features. To the best of our knowledge, this is the first example for highly selective detection of 2,4-DNP. More importantly, theoretical calculation and control experiments unveiled that the energy transfer is the main mechanism for highly detection of 2,4-DNP. This work will pave the way for designing highly efficient luminescent chemosensors.