Molecular Adsorbing Host•Guest (MAHG) Crystals: A New Paradigm for Porous Materials?

Since the discovery of host•guest complexes, we have assisted to huge developments of this part of chemistry, liquid state studies brightly leading the way. In this context, numerous macrocycles and cages have shown exceptional relevance for selective and controllable guest capture and release mainly based on 1:1 host•guest complexes. With such attributes, applications pertaining to sequestration, separation, catalysis, template synthesis and more generally to biology and materials science have flourished over time. Comparatively, the solid-state chemistry of host•guest complexes is less developed, especially that involving macrocyclic hosts. In this context, we recently reported the crystal structure of what could be the first of a series of Molecular Adsorbing Host•Guest (MAHG) crystals featured by several new properties. Whereas a rapidly growing field today exists about porous Hydrogen-bonded Organic Frameworks (HOFs), some composed of macrocyclic "hosts only", an unchartered territory appears within reach for (macrocyclic) "host•guest complexes". Given the huge diversity of host•guest complexes described in the liquid state, rapid developments of MAHG type materials are expected in the near future.