Dynamic Covalent Macrocycles Constructed via Organic Templates

Dynamic covalent macrocycles templated by organic molecules have. been thoroughly reviewed. Organic templates have much larger sizes than metal ions, and therefore are suitable to template the formation of macrocycles with much larger cavity. Meanwhile, there are a variety of organic molecules, which may work as templates. Their structures can be tailor-made through various organic reactions. Out of many dynamic covalent bonds, there are three popular types which are often used to construct dynamic covalent macrocycles via template effect: disulfide, boronic ester, and imine. The reversibility of former two bonds can be switched on or off through changing the conditions. While imine bonds can be reduced to kinetically inert chemical bonds. Thus, the thermodynamically stable macrocycles in the presence of templates can be converted to the corresponding kinetically inert macrocycles, providing a new method for the preparation of macrocyclic hosts. In addition, the host-guest binding motifs based on dynamic covalent macrocycles can be used to construct more complex supramolecular architectures, for example, rotaxanes and catenanes.