Formation of trigons in a metal–organic framework: The role of metal–organic polyhedron subunits as meta-atoms

Shape control of metal–organic materials on the meso- and macroscale has been an important theme due to emerging properties. Particularly, chemical etching has been useful to create various forms such as core–shells and hollow crystals in metal–organic frameworks. Here we present a unique chemical etching strategy to create trigonal patterned surfaces in metal–organic frameworks. The mechanism suggests that metal–organic polyhedron subunits serve as meta-atoms, playing a crucial role in the formation of trigons on the surface. Such a patterned surface in porous solids can be utilized in meta-surface applications in the foreseeable future.