Functionalised Al(III) metal organic frameworks for fluorescence sensing of nitroaromatic vapours

The employment of fluorescence sensors provides a platform for rapid and efficient in-field detection of nitroaromatic compounds and is gaining increasing research ground. Herein, we report the synthesis and characterisation of three new fluorescent Al(iii) MOFs, structurally analogous to MIL-53, with the assigned formula {Al(OH)(bdc)(1-n)(L-1)(n)}center dot xsolv (bdc(2-) = terephthalate; L-1 = 2-((benzyl)amino)-terephthalate). L-1 is a strongly fluorescent dicarboxylic ligand with a pendant pi-electron rich aromatic group suitable for donor-acceptor interactions with electron-deficient nitroaromatic guests. Our MOFs show strong fluorescence quenching upon exposure to vapours of nitrobenzene, 1,3-dinitrobenzene, 4-nitrotoluene, and 2,4-dinitrotoluene. Additionally, we prepare and study MOF-polymer composites in the form of thin films that are strongly quenched in the presence of nitrobenzene vapours.