AIE-active supramolecular gel systems

Supramolecular hydro- and organo-gels formed by low molecular weight compounds constitute a special class of soft materials and are currently receiving considerable attention on account of their unique features which could spur their adoption in novel technological applications. In recent years, aggregation-induced emission (AIE)-active supramolecular gels, which exhibit remarkable enhancement in their fluorescence emission on a reversible sol-to-gel phase transition process, have been the focus of attentive and widespread theoretical and experimental studies. This chapter summarizes the latest advances in this promising field by the description of selected representative examples. A brief account of the principles and general properties of supramolecular gels constitutes the first section, which serves as an introduction to the field. The second part is devoted to the practical methods for the preparation and characterization of AIE-active supramolecular gel systems as well as to the mechanisms of the emission enhancement. Finally, examples of AIE-active supramolecular gels used as sensors for metal ions, anions, or neutral molecules, and as probes in biomedical applications are described in order to provide the reader with a comprehensive survey of the different research directions which have contributed so far to the development of the field, especially in terms of potential applications.