Rational design of an AIE-active metal-organic framework for highly sensitive and portable sensing nitroaromatic explosives

Herein, we report a new metal-organic framework with an AIE ligand (H4TCPP = 2,3,5,6-tetra-(4-carboxyphenyl)pyrazine) and Mg2+ ions, that is, [Mg2(H2O)4TCPP]·DMF·5CH3CN (Mg-TCPP, TCPP = tetra-(4-carboxyphenyl)pyrazine) for detection of nitroaromatic explosives. Due to the coordination effect and restricted intramolecular rotation, Mg-TCPP exhibits bright blue light. As a fluorescent sensor, Mg-TCPP exhibits high selectivity and sensitivity for sensing 2,4,6-trinitrophenol (TNP) by quenching behaviors with the Stern-Volmer quenching constant (KSV) of 3.63×105 L/mol and achieves the low limit of detection of 25.6 ppb, which is beyond most of the previously reported fluorescent materials. Notably, the portable Mg-TCPP films are prepared and it can be used for rapid and sensitive TNP detection in a variety of environments including organic solvent and aqueous solution. Moreover, TNP vapor can be detected within 3 min by naked eye and the film could be regenerated under simple solvent cleaning.