Pillar-layered MOFs: functionality, interpenetration, flexibility and applications

Pillar-layered metal–organic frameworks (MOFs) are among the most interesting research areas in crystalline materials. Due to the great number of reports related to pillar-layered MOFs, investigating their structural diversity, properties and applicability as multi-donor porous frameworks is of great interest. Modifying pillar moieties as a third building block of pillar-layered MOFs, together with metal nodes and oxygen donor linkers, can enhance control of the structure assembly, leading to specific properties of the obtained structures. Although the past decade has witnessed remarkable advances in this research area, pillar-layered MOFs have not been reviewed as an independent subject to date. Therefore, a review summarizing their performance is greatly needed. This review covers issues related to pillar-layered MOFs, including their structural properties, synthesis, stability, diversity of linkers, and improved applicability. Finally, pillar linkers are studied separately according to their diverse donor atoms and functional groups.