An Approach To Thermodynamically Controlled Supramolecular Assembly Possessing An Integral Locking Mechanism

摘要

The power of template-directed synthesis under thermodynamic control has been harnessed for the efficient preparation of intricate, and sometimes unexpected, molecular structures. Such efficiencies are the result of the error-correcting nature of reversible covalent bond forming reactions; non-optimal bonds are cleaved and the components recycled toward an energetic structural minimum. A number of reactions have been explored in establishing this field-dynamic combinatorial chemistry (DCC)-arguably the most valuable of which provide a means for switching off reversibility and thereby locking-in a thermodynamically mandated structure. For example, imine exchange may be terminated via C=N reduction while processes involving olefin, disulfide, and hydrazide linkages are shut down by catalyst removal. We describe here the application to a supramolecular assembly process of a reversible carbonyl chemistry-based reaction that additionally provides the facility, via a subsequent irreversible dehydration, to permanently fix an evolved molecular structure. This approach, by nature of its derivation from familiar reactions and the application of simple base or acid catalysis, has potentially broad general utility.