Host–Guest Chemistry in Surface-Confined Two-Dimensional Covalent Organic Frameworks

The use of surface-synthesized, two-dimensional covalent organic frameworks (COFs) as host networks for capturing a variety of guest species is an emerging area of research. This article highlights recent advances made in the field. The most popular chemistries used for the on-surface synthesis of monolayer COFs are discussed. Advantages of the surface synthesis of COFs over solution synthesis protocols are highlighted. Monolayer COF films synthesized under ultrahigh vacuum environment as well as those obtained under ambient conditions are described. The nanoscale characterization of COF host networks and monolayer COF-based host–guest architectures using scanning tunneling microscopy is discussed.