A Review on Low?Molecular?Weight Gels Driven by Halogen?Effect
As a potentially powerful supramolecular tool similar to hydrogen bond, halogen bond shows great potential in supramolecular chemistry. Due to the directivity, tunability, hydrophobicity and donor atom size of the halogen bond, it can effectively promote the assembly of different structures molecules to form various types of low?molecular?weight gels (LWMGs), providing a facile platform for the application in sensing, anti?counterfeit, information storage, biology, etc.As a new type of non?covalent interaction similar to hydrogen bond, halogen bond has become an important supramolecular tool in crystal engineering, material chemistry, biological science, etc., due to its unique properties. In fact, halogen bond has been confirmed on the effect of molecular assemblies and soft materials, and widely used in various functional soft materials including liquid crystals, gels and polymers. In recent years, halogen bonding has aroused strong interest in inducing molecular assembly into low?molecular?weight gels (LMWGs). To the best of our knowledge, there is still a lack of in?depth review of this field. So, in this paper, the recent progress of LMWGs driven by halogen bonding is reviewed. According to the number of components forming halogen bonded gels, the structural characteristics of halogen bonded supramolecular gels, the relationship between halogen bonding and other non?covalent interactions, as well as the application fields of halogen bonded gels are introduced, respectively. In addition, the challenges faced by halogenated supramolecular gels at present and their development prospects in future have been proposed. We believe that the halogen bonded gel will have more impressive applications in the next few years, opening exciting new opportunities for the development of soft materials.