Metal–organic frameworks based on multicarboxylate linkers

When designing metal–organic frameworks (MOFs), linker design is one of the most important factors in constructing a wide variety of structures. Judicious choice of linker size, geometry, and connectivity can create diverse structures and topologies, which can aid in the quest to design MOFs with both high stability and permanent porosity. Multi-connected linkers have become a focus in the MOF community, as high connectivity can improve stability and tunability of frameworks. In particular, multicarboxylate ligands have been reported extensively in the literature to construct stable MOFs with versatile pore environments, which can be termed as metal-multicarboxylate frameworks (MMCFs). These structures have great application potential in gas adsorption and separation, catalysis, and sensing. Herein, we review the literature on multicarboxylate linkers (nCOOH ≥ 3) in MOF systems and their applications, with specific emphasis on how high linker connectivity affects properties of MOFs such as topology, porosity, stability, and functionality.