With this new award, the Organic and Macromolecular Chemistry Program supports the work of Professor Lyle D. Isaacs of the Chemistry Department at the University of Maryland, College Park, MD. This research will investigate the use of cucurbit[10]uril (CB[10]), the largest cucurbit[n]uril known, as a molecular container in aqueous solution. In particular, the use of CB[10] as molecular chaperone to control the folding of melamine oligomers into well-defined conformations will be explored. In addition, complexes between CB[10] and cationic (metallo)porphyrins will be prepared and their use in forming termolecular complexes with suitable molecular guests will be investigated. The CB[10]-porphyrin complexes will also be applied as catalysts for oxidation reactions in water. This project will also investigate the possibility of allosteric control of the macromolecular conformation of cationic calixarenes inside CB[10] by the introduction of small molecules.
These experiments will evaluate the potential for cucurbiturils to function as real-world molecular containers for applications such as drug delivery. This project will foster the training of students at all academic levels, including a number from underrepresented groups, as interdisciplinary scientists.
(CB[10]). In everyday life, containers are used to protect their contents from damage or to ship them to other locations. Just like everyday containers, molecular container compounds are able to hold on to molecules and thereby change their properties. The CB[10] container was particularly interesting to us because it is one of the largest molecular containers available with a volume of approx. one cubic nanometer. The larger the container, the more interesting the cargo it can contain. We made numerous discoveries under this grant; among the most exciting were that CB[10]: a) was able to hold onto oligomeric compounds and fold them up into specific shapes (much like proteins are induced to fold), b) undergo changes in shape upon addition of a specific chemical (in much the same way that proteins change their shape / function in response to specific chemicals), c) that CB[10] is able to encapsulate porphyrin compounds in much the same way that metalloproteins do. As part of the work on this grant we also improved our understanding of the mechanism of CB[n] formation (basically a roadmap that explains how these compounds form) which allows us to prepare related molecular containers in a better way. These related molecular containers include compounds known as nor-seco-cucurbiturils that lack one or more of the bridging CH2-groups that are typical of the CB[n] compounds. Nor-seco CB[n] compounds are particularly interesting becuase they have more flexible cavities that wrap themselves around their guests in an induced fit type process. The students (undergraduates, graduates, postdoctoral fellows) working on this project received training in supramolecular chemistry and the typical analytical tools used in to study these compounds. Through this research project they became well trained interdisciplinary scientists who have gone on to careers in industry, academics, and medicine.
