AIE-active metal–organic frameworks: facile preparation, tunable light emission, ultrasensitive sensing of copper(ii) and visual fluorescence detection of glucose

Abstract

By binding aggregation-induced emission luminogens (AIEgens) with nanoscale ZIF-8, a series of novel luminescent metal–organic frameworks (LMOFs) with good photostability and excellent dispersibility have been facilely fabricated. The developed AIE-active MOFs not only inherit the intriguing AIE properties of AIEgens, including excited-state intramolecular proton transfer (ESIPT) properties, intense solid-state luminescence and large Stokes shifts (115–202 nm), but also show surprisingly boosted fluorescent emission efficiency (over 16 times) when compared with the original fluorescence of AIEgens. Meanwhile, the emission of AIE-active MOFs could also be finely engineered by varying the substituents on AIEgens. And as a proof of concept, the selected AIE-active MOF-2 (LMOF-2) served as a novel fluorescent probe for detecting copper ions (Cu²⁺), and a considerable response range (1–100 nM) and a sensitive picomolar detection limit (550 pM) were favorably obtained. More importantly, based on a glucose oxidase (GOD) catalyzed cascade redox reaction of LMOF-2/GOD nanocomposites, a fluorescent allochroic test strip was favourably developed for visual detection of glucose within a normal concentration range of fasting blood-glucose in human sera (3–8 mM), and has great potential to be applied in on-site assay of glucose in real serum samples due to its praiseworthy specificity and selectivity.