Organic nanoporous structures

Research on microporous materials, hollow solids with channels and cavities that include small guest molecules, has advanced in fundamental and applied aspects during 1999–2000. The retrosynthesis of crystal structures in terms of robust supramolecular synthons (recognition motifs) and functionalised organic molecules (building blocks) has led to the design of new porous architectures and modification in the properties of existing host materials. Even as conventional O–H⋯O and N–H⋯O hydrogen bonds continue to be used to attain these goals, weak hydrogen bonds and heteroatom interactions, such as C–H⋯O, halogen⋯halogen, strengthened by multi-point recognition and cooperativity effects, have emerged in new design strategies. A proper understanding of pseudopolymorphism, the phenomenon of solvent inclusion in crystals, will promote the next phase of host–guest research.