Functional Molecular Flasks: New Properties and Reactions within Discrete, Self-Assembled Hosts

The application of self-assembled hosts as "molecular flasks" has precipitated a surge of interest in the reactivity and properties of molecules within well-defined confined spaces. The facile and modular synthesis ofself-assembled hosts has enabled a variety ofhosts of differing sizes, shapes, and properties to be prepared. This Review briefly highlights the various molecular flasks synthesized before focusing on their use as functional molecular containers-specifically for the encapsulation ofguest molecules to either engender unusual reactions or unique chemical phenomena. Such self-assembled cavities now constitute a new phase ofchemistry, which cannot be achieved in the conventional solid, liquid, and gas phases. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.