As the field of supramolecular chemistry expands, the use of host molecules as nanoscale reaction vessels has become increasingly important. Deep-cavity cavitands octa-acid (OA) and tetra-endo-methyl octa-acid (TEMOA) are established molecules for host-guest binding interactions. Unlike OA, which forms assemblies no larger than dimeric capsules, TEMOA is known to form dimeric, tetrameric, and hexameric assemblies. The internal volume of these tetramers and hexamers (1400-1500 Å3 and 3200-3700 Å3, respectively) make them the largest known water-soluble host assemblies formed via the hydrophobic effect. The ability to form larger assemblies makes TEMOA an ideal reaction vessel for large and unique molecules. In this work, TEMOA is shown to bind terpenes nerol and geranylgeraniol to form dimeric and tetrameric assemblies, respectively. And while supramolecular chemistry possesses a wide range of techniques for evaluating the thermodynamic properties of solution-based events such as these, few techniques provide insight into the kinetics of those events. To better understand the kinetics of guest exchange rates within supramolecular capsules a new NMR technique – guest exchange saturation transfer (GEST) – was developed to study the exchange rates between the free and bound states of a range of poly-fluorinated guest molecules to OA and TEMOA. It is of interest to expand this technique to study the kinetics of larger assemblies as well.

Larger assemblies and guest exchange in molecular containers

255th National Meeting (2018)

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