Site-selective cyclometalation of a metal–organic framework

Abstract

Although porous materials, including metal–organic frameworks (MOFs), can be functionalized using heterogeneous reactions (solution–solid, gas–solid), there are no reports that modify chemically identical sites in a spatially selective, periodic fashion. Herein, the cyclometalation of two non-interpenetrated MOFs and an interpenetrated MOF in the solid state is reported using [Ir(COD)(OCH₃)]₂ and [Rh(COD)(Cl)]₂ (COD = 1,5-cyclooctadiene). Incredibly, the cyclometalation of the interpenetrated MOF occurs only on ligands that lie along, one crystallographic axis, providing an unprecedented example of site-selective postsynthetic modification (PSM). This represents a degree of control on the functionalization of a porous, material that has not been otherwise realized, and is achieved in part because of the crystalline, periodic nature of MOFs. Furthermore, it was found that the degree of cyclometalation, increases the sorption capacity of the interpenetrated MOF.