Roztocki Kornel, Gromelska Wiktoria, Formalik Filip, Giordana Alessia, Andreo Luca, Mahmoudi Ghodrat, Bon Volodymyr, Kaskel Stefan, Barbour Leonard J, Janiak Agnieszka, Priola Emanuele
Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
Department of Micro, Nano, and Bioprocess Engineering, Faculty of Chemistry, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland.
ACS Mater Lett. 2023 Mar 23;5(4):1256-1260. doi: 10.1021/acsmaterialslett.3c00068. eCollection 2023 Apr 3.
Shape-memory polymers and alloys are adaptable materials capable of reversing from a deformed, metastable phase to an energetically favored original phase in response to external stimuli. In the context of metal-organic frameworks, the term shape-memory is defined as the property of a switchable framework to stabilize the reopened pore phase after the first switching transition. Herein we describe a novel flexible terpyridine MOF which, upon desolvation, transforms into a nonporous structure that reopens into a shape-memory phase when exposed to CO at 195 K. Based on comprehensive experimental studies (SC-XRD and PXRD) and DFT energetic considerations combined with literature reports, we recommend dividing shape-memory MOFs into two categories, viz responsive and nonresponsive, depending on the transformability of the gas-free reopened pore phase into the collapsed phase. Furthermore, considering the methodological gap in discovering and understanding shape-memory porous materials, we emphasize the importance of multicycle physisorption experiments for dynamic open framework materials, including metal-organic and covalent organic frameworks.
形状记忆聚合物和合金是适应性材料，能够响应外部刺激，从变形的亚稳相转变为能量上更有利的原始相。在金属有机框架的背景下，形状记忆一词被定义为可切换框架在首次切换转变后稳定重新开放的孔相的特性。在此，我们描述了一种新型的柔性三联吡啶金属有机框架，在脱溶剂后，它转变为无孔结构，当在195 K下暴露于CO时重新开放为形状记忆相。基于全面的实验研究（单晶X射线衍射和粉末X射线衍射）以及密度泛函理论能量考量，并结合文献报道，我们建议根据无气体重新开放的孔相转变为塌陷相的可转化性，将形状记忆金属有机框架分为两类，即响应型和非响应型。此外，考虑到发现和理解形状记忆多孔材料方面的方法学差距，我们强调多循环物理吸附实验对于动态开放框架材料（包括金属有机框架和共价有机框架）的重要性。
