Bönisch Nadine, Maliuta Mariia, Senkovska Irena, Bon Volodymyr, Petkov Petko, Plätzer Christel, Müller Philipp, Kaskel Stefan
Chair of Inorganic Chemistry I, Technische Universität Dresden, 01069 Dresden, Germany.
Department of Organic Chemistry and Pharmacognosy, Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria.
Inorg Chem. 2021 Feb 1;60(3):1726-1737. doi: 10.1021/acs.inorgchem.0c03218. Epub 2021 Jan 13.
Linker elongation is an important method to systematically adjust porosity and pore size in isoreticular MOFs. In flexible structures, this approach opens the possibility for the systematic analysis of the building blocks and their contribution to the overall flexible behavior enabling tuning of the framework responsivity toward molecular stimuli. In this work, we report two new compounds isoreticular to the highly flexible pillared layer structure DUT-8(Ni) ([Ni(2,6-ndc)(dabco)], 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicylo[2.2.2]octane). Aromatic linker 2,6-ndc was substituted by longer carboxylic linkers, namely, 4,4'-biphenyldicarboxylate (4,4'-bpdc) and 4,4'-stilbenedicarboxylate (4,4'-sdc), while the dabco pillar was retained. The structural response of the new compounds toward the desolvation and adsorption of various fluids was studied using advanced in situ PXRD techniques, demonstrating distinct differences in the flexible behavior of three compounds and disclosing the impact of linker structure on the framework response. Theoretical calculations provide mechanistic insights and an energetic rationale for the pronounced differences in switchability observed. The energetics of linker bending and linker-linker dispersion interactions govern the phase transitions in investigated MOFs.
连接体延长是系统调节同网状金属有机框架（MOF）孔隙率和孔径的重要方法。在柔性结构中，这种方法为系统分析构建单元及其对整体柔性行为的贡献开辟了可能性，从而能够调节框架对分子刺激的响应性。在这项工作中，我们报道了两种与高度柔性的柱状层结构DUT-8(Ni)（[Ni(2,6-ndc)(dabco)]，2,6-ndc = 2,6-萘二甲酸，dabco = 1,4-二氮杂双环[2.2.2]辛烷）同网状的新化合物。芳香族连接体2,6-ndc被更长的羧酸连接体取代，即4,4'-联苯二甲酸（4,4'-bpdc）和4,4'-二苯乙烯二甲酸（4,4'-sdc），同时保留dabco支柱。使用先进的原位粉末X射线衍射（PXRD）技术研究了新化合物对各种流体脱溶剂化和吸附的结构响应，证明了三种化合物在柔性行为上的明显差异，并揭示了连接体结构对框架响应的影响。理论计算为观察到的显著开关差异提供了机理见解和能量原理。连接体弯曲的能量学和连接体-连接体色散相互作用控制着所研究MOF中的相变。
