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 reserach ground. Herein, we report the synthesis and characterisation of three new fluorescent Al(ΙΙΙ) MOFs, structurally analogous to MIL–53, with the assigned formula {Al(OH)(bdc)1-n(L–1)n}·xsolv (bdc2- = terephthalate; L–1 = 2–((benzyl)amino)-terephthalate). L–1 is a strongly fluorescent dicarboxylic ligand with a pendant π–electron rich aromatic group suitable for electron transfer processes towards electron–deficient nitroaromatic guests. Our MOFs show strong fluorescence quenching upon exposure to vapours of nitrobenzene, 1,3-dinitrobenzene, 4-nitrotoluene, 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.