Yttrium-based metal–organic frameworks built on hexanuclear clusters

Yttrium-based metal–organic frameworks built on hexanuclear clusters (Y₆-MOFs) represent an important subgroup of MOFs that are assembled from Y₆ clusters and diverse organic linkers, featuring a variety of topologies. Due to the robust Y–O bonds and high connectivity of hexanuclear SBUs, Y₆-MOFs are generally thermally stable and resistant to water. Additionally, their pore structures are highly tunable through the practice of the reticular chemistry strategy, resulting in excellent performance in gas adsorption and separation related applications. Y₆-MOFs are structurally analogous to Zr₆-MOFs; however, the existence of charge-balancing cations in Y₆-MOFs serves as an additional pore structure regulator, enhancing their tailorability with respect to pore shape and dimensions. In this Frontier article, we summarize the main advances in the design and synthesis of Y₆-MOFs, with a particular focus on the precise engineering of their pore structure for gas separation. Future directions of research efforts in this field are also discussed.