Anions-responsive supramolecular gels: A review

Recently, supramolecular low-molecular-weight gels have attracted more and more attentions and have potential applications in many areas due to the dynamic nature of noncovalent interactions that form the gel networks. The adaptability, adjustability and stimulus responsibility were the desired properties of supramolecular gel beyond traditional nanoscale materials. Of the external stimulus sources, anions are of particular interest because of their essential role in environment and many biological processes. Generally, the design of anions-responsive supramolecular gelators contained three parts: the binding site (or reaction site), the linker and the assistant self-assembly moieties (usually hydrophobic or hydrophilic groups). In this review, we discuss three types of anions-responsive supramolecular gels by giving the latest summaries (from 2015 to 2020), including the responsive properties of various structures, design strategy, mechanisms and drawbacks. We also believe that although current researches of those gels are mainly focused on the visual detection of anions in vitro, with the deep understanding of the properties and mechanism of the anions -responsive supramolecular gels, the applications should be paid more and more attention in vivo like anionic related drug targeted delivery and rapid detection of diseases