Abstract:
Cucurbiturils are a series of pumpkin-shaped macrocyles obtained from an acid-catalyzed condensation reaction of glycoluril and formaldehyde. They can bind with gases, small molecules and positive charged guests, and have been widely used in the fields of separation, catalysis, pharmaceutical, interlocked molecules, and supramolecular architectures etc. Recently, our group has synthesized a new class of Helianthus-like cucurbituril analogues (TD
n,
n is the number of the repeated units) using the condensation of glycoluril-like propanediurea (2, 4, 6, 8-tetraazabicyclo3.3.1nonane-3, 7-dione, TD) or its derivatives with formaldehyde. Compared with glycoluril, substituents can be introduced more easily on the central methylene position of TD and the corresponding derivatives have less influence upon the cucurbituril-forming cyclization. It should be noted that the value of
n in cucurbituril family is reduced to 4 for the first time and TD4 is of smaller cavity than ever. Moreover, some TD
ns bind selectively to metal ions, and some bind strongly with protonated amines in portal binding mode, and a series of TD
n-based supramolecular polymers have consequently been set up, which would lay a solid foundation for their future applications in areas such as supramolecular chemistry.