Simultaneous Encapsulation: Molecules Held at Close Range

Abstract

Reversible encapsulation creates spaces where molecules are temporarily isolated from others in solution. Molecules are held within the space of the capsule for lifetimes ranging from milliseconds to hours, and conventional NMR spectroscopy can be used to report on the chemical and magnetic environment as well as the arrangement of the molecules in the encapsulation complex. The complexes self-assemble when, and only when, the spaces inside the capsules are appropriately filled. The weak intermolecular forces that hold these self-assemblies together allow equilibration of the encapsulation complexes at ambient temperatures and pressures in the liquid phase. When two or more molecules are simultaneously encapsulated, intermolecular phenomena are revealed in solution that cannot be observed by other methods. We describe here the unique behavior that emerges from molecules that are simultaneously encapsulated and includes new forms of stereochemistry, isomerism, and asymmetry inside capsules.

Chemical mimicry of viral capsid self-assembly

“…Many of these constructs use two molecular subunits that assemble through hydrogen bond networks or metal coordination. One of the largest molecular containers, which were formed from six calixarene subunits in cuboctahedral symmetry, could accommodate as many as eight benzene molecules (10). To the best of our knowledge, no synthetic strategy that incorporates the icosahedral symmetry of viral capsids has been reported.…”

Trimeric and hexameric calixarene-based capsules

“…26 The methods of their construction mainly involve selfassembly via hydrogen bonds or metal coordination. 25 The bowl-shaped resorcin [4]arene and pyrogallol [4]arene macrocycles form large hexameric capsules, i.e.…”

“…Substitution of hydrogen atoms for metal ions results in structural preservation of hexameric structure, while introducing inorganic functionality. In the study of hexameric capsules their guest affinity, tautomeric equilibria and isotope effects 7,8,26 were examined. It should be pointed out that the investigation of dimeric cylindrical capsules 14 is more detailed than that of hexameric capsules of resorcinarenes and pyrogallolarenes.…”

“…26,[48][49][50] It should be pointed out that pyrogallol [4]arenes contain four additional upper rim hydroxyl groups, as compared with resorcinarenes; this fact results in a larger number of hydrogen-bonding interactions in formed hexamers and, as a consequence, the higher stability than in the case of resorcinarene-based hexameric capsules. 50,51 Resorcinarenes and pyrogallolarenes form hexameric capsules in the solid state and in solution via a network of hydrogen bonds.…”

Catalyzing Methanolysis of Alkyl Halides in the Interior of an Amphiphilic Molecular Basket

“…Not surprisingly, chemists have long been interested in generating "nanoreactors" to control chemical reactivity. 1,2 Nanoreactors prepared through either covalent construction or self-assembly have been reported. 3 For example, Rebek and co-workers functionalized resorcinarene-derived deep cavitands and used them to achieve molecular recognition and to enhance chemical reactivity.…”