Host-guest supramolecular systems containing AIE-active building blocks

This article focuses on displaying the progresses in the cross-discipline research area of host-guest supramolecular systems and aggregation-induced emission (AIE) materials in the most recent 5 years. The AIE phenomenon is briefly described, and the underlying mechanism for AIE phenomenon observed for three different kinds of materials is introduced. Basically, the restriction of intramolecular motions (RIMs) are the cause of fluorescence emission. A few of representative host-guest supramolecular systems are introduced with selected examples. Cyclodextrins, crown ethers, and pillar[. n]arenes are employed as hosts and AIE-active compounds as guests. The host-guest interaction leads to a RIM process and triggers enhanced emission when bound to the guest molecules. Metal-organic frameworks (MOFs) are ideal synthetic hosts, and AIE-active compounds can be used either as the building blocks of the host or as the guests to be held in the hosts. The unique microenvironment in MOFs offers the opportunity to get more detailed understanding of mechanism for AIE phenomenon and provides a series of novel multifunctional MOFs with fluorescent property. The host-guest supramolecular assemblies show promising applications in chemo-/biosensors, bioimaging agents, and stimuli-responsive fluorescent materials.