Department of Chemistry and ∥Integrated Molecular Structure Education and Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
J Am Chem Soc. 2017 Aug 16;139(32):11020-11023. doi: 10.1021/jacs.7b06287. Epub 2017 Aug 8.
Co-crystallization of K and Li ions with γ-cyclodextrin (γ-CD) has been shown to substitute the K ion sites partially by Li ions, while retaining the structural integrity and accessible porosity of CD-MOF-1 (MOF, metal-organic framework). A series of experiments, in which the K/Li ratio was varied with respect to that of γ-CD, have been conducted in order to achieve the highest possible proportion of Li ions in the framework. Attempts to obtain a CD-MOF containing only Li ions resulted in nonporous materials. The structural occupancy on the part of the Li ions in the new CD-MOF has been confirmed by single-crystal X-ray analysis by determining the vacancies of K-ion sites and accounting for the cation/γ-CD ratio in CD-MOF-1. The proportion of Li ions has also been confirmed by elemental analysis, whereas powder X-ray diffraction has established the stability of the extended framework. This noninvasive synthetic approach to generating mixed-metal CD-MOFs is a promising method for obtaining porous framework unattainable de novo. Furthermore, the CO and H capture capacities of the Li-ion-substituted CD-MOF have been shown to exceed the highest sorption capacities reported so far for CD-MOFs.
用 γ-环糊精（γ-CD）共晶化 K 和 Li 离子已被证明可以部分用 Li 离子取代 K 离子位，同时保持 CD-MOF-1（MOF，金属有机骨架）的结构完整性和可及的孔隙率。进行了一系列实验，其中 K/Li 比相对于 γ-CD 变化，以实现框架中尽可能高的 Li 离子比例。试图获得仅含有 Li 离子的 CD-MOF 导致无孔材料。通过单晶 X 射线分析确定 K-离子位的空位，并考虑 CD-MOF-1 中的阳离子/γ-CD 比，从而确认 Li 离子在新的 CD-MOF 中的结构占有率。通过元素分析也证实了 Li 离子的比例，而粉末 X 射线衍射则建立了扩展框架的稳定性。这种非侵入性的合成方法生成混合金属 CD-MOF 是获得无法从头获得的多孔框架的有前途的方法。此外，Li 离子取代的 CD-MOF 的 CO 和 H 捕获能力已经超过迄今为止报道的 CD-MOF 的最高吸附容量。
