Flexibility in DUT-8(Cu) Metal–Organic Framework: Impact of Cluster, Stress, History, and Hierarchical Texture
Mariia Maliuta, Irena Senkovska, V.V. Romaka, Mariia Roslova, Zhehao Huang, Petko St. Petkov, Volodymyr Bon, Stefan Kaskel
Abstract
The flexibility of metal–organic frameworks (MOFs) featuring stimuli-responsive structural transitions is often governed not only by the chemical composition and topology but also by orthogonal factors such as particle size, desolvation method, and history of the sample. A precise understanding of the mechanism behind such observations has been lacking up to now, and there are still substantial open questions concerning the impact of sample treatment history. The DUT-8(M) family ([M$_2$(2,6-ndc)2(dabco)]$_n$, 2,6-ndc = 2,6-naphthalene dicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane), encompasses isostructural compounds based on Ni, Zn, Co, and Cu in the cluster node and is representative of pillared layer MOFs, often showing flexible behavior. In this contribution, we discuss a possible explanation for the differences in flexibility observed in desolvated phases of DUT-8(Cu). Theoretical calculations and crystallographic data shed light on the preferred formation of interpenetrated confined closed pore phases in DUT-8(Cu) in contrast to DUT-8(Ni, Co, Zn) where the closed pore phases are formed.