Nanoscale molecular containers

Over the last few years, there has been a breakthrough in the design and synthesis of nanoscale molecular containers-cavitands, (hemi)carcerands, and capsules. These nanocavities are designed for selective binding, separation and sensing of smaller molecules and ions, molecular transport and delivery, stabilization of reactive intermediates, and catalysis through encapsulation. They also mimic the hydrophobic pockets of enzymes. The field has grown since the first hollow calixarenes of Collet, Cram, and Gutsche, which were able to trap a single solvent or gas molecule, in the early 1980s, to investigations of giant cavities of 15-20 Angstrom inner dimensions and 1500 Angstrom(3) internal volume. This reflects current trends in molecular recognition which are rapidly moving towards nanotechnology and microfabrication on the one hand and molecular biology on the other. Recently prepared nanocavities are ready to be employed for encapsulation of drugs and their active transport/delivery through cell membranes. Cavity-containing informationally rich polymers, sensing materials and polymer-supported microreactors are also in sight. These and many other applications can only be possible if general approaches towards construction of nanoscale molecular containers are developed and if the key rules governing their inclusion complexes are understood at the level of their organic chemistry.