Structural design and applications of pillar-layered MOFs

Metal-organic frameworks (MOFs) have attracted widespread attention due to their controllable components, topologies, properties and applications. Especially, pillar-layered (PL) MOFs, which can integrate metal centers, layer ligands and pillaring ligands into a single MOF, exhibit enormous advantages in the construction of diverse and functionally adjustable MOF materials. In PL-MOFs, the layers can be regarded as networks that extend infinitely along two-dimensional directions induced by layer ligands and metal centers, while the third dimension is free for the extension of pillaring ligands. In this sense, this good spatial distribution between different components allows for regulation of topologies, pore sizes/environments, and flexibility by precise design/choice of different components. Correspondingly, the synergistic or contradictory properties among different components can be integrated within a single material to endow it with multifunctionality. This feature article covers the design and regulation principles of PL-MOFs and some selected examples of their properties and applications. Specifically, the relationships between structural modulation and properties of PL-MOFs and the pillar-layered strategy for the construction of multicomponent MOFs are highlighted. We hope that this review will render novel guidance for functionally oriented PL-MOF materials design. Additional current challenges and perspectives related to PL-MOFs are also discussed.