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Organic Counteranion Co-assembly Strategy for the Formation of γ-Cyclodextrin-Containing Hybrid Frameworks
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-01-14 , DOI: 10.1021/jacs.9b12527
Dengke Shen 1 , James A Cooper 1 , Peng Li 2 , Qing-Hui Guo 1 , Kang Cai 1 , Xingjie Wang 1 , Huang Wu 1 , Hongliang Chen 1 , Long Zhang 1 , Yang Jiao 1 , Yunyan Qiu 1 , Charlotte L Stern 1 , Zhichang Liu 3 , Andrew C-H Sue 4 , Ying-Wei Yang 5 , Fehaid M Alsubaie 6 , Omar K Farha 1 , J Fraser Stoddart 1, 4, 7
Affiliation  

A class of γ-cyclodextrin-containing hybrid frameworks (CD-HFs) has been synthesized, employing γ-cyclodextrin (γ-CD) as the primary building blocks, along with 4-methoxysalicylate (4-MS-) anions as the secondary building blocks. CD-HFs are constructed through the synergistic exploitation of coordinative, electrostatic, and dispersive forces. The syntheses have been carried out using an organic counteranion co-assembly strategy, which allows for the introduction of 4-MS-, in place of inorganic OH-, into the cationic γ-CD-containing metal-organic frameworks (CD-MOFs). Although the packing arrangement of the γ-CD tori in the solid-state superstructure of CD-HFs is identical to that of the previously reported CD-MOFs, CD-HFs crystallize with lower symmetry and in the cuboid space group P43212-when compared to CD-MOF-1, which has the cubic unit cell of I432 space group-on account of the chiral packing of the 4-MS- anions in the CD-HF superstructures. Importantly, CD-HFs have ultramicroporous apertures associated with the pore channels, a significant deviation from CD-MOF-1, as a consequence of the contribution from the 4-MS- anions, which serve as supramolecular baffles. In gas adsorption-desorption experiments, CD-HF-1 exhibits a Brunauer-Emmett-Teller (BET) surface area of 306 m2 g-1 for CO2 at 195 K, yet does not uptake N2 at 77 K, confirming the difference in porosity between CD-HF-1 and CD-MOF-1. Furthermore, the 4-MS- anions in CD-HF-1 can be exchanged with OH- anions, leading to an irreversible single-crystal to single-crystal transformation, with rearrangement of coordinated metal ions. Reversible transformations were also observed in CD-MOF-1 when OH- ions were exchanged for 4-MS- anions, with the space group changing from I432 to R32. This organic counteranion co-assembly strategy opens up new routes for the construction of hybrid frameworks, which are inaccessible by existing de novo MOF assembly methodologies.

中文翻译:

用于形成含有 γ-环糊精的混合框架的有机反阴离子共组装策略

已经合成了一类含 γ-环糊精的杂化骨架 (CD-HF),采用 γ-环糊精 (γ-CD) 作为主要结构单元,以及 4-甲氧基水杨酸 (4-MS-) 阴离子作为二级结构块。CD-HF 是通过协同利用协调力、静电力和色散力构建的。合成是使用有机反阴离子共组装策略进行的,该策略允许将 4-MS- 代替无机 OH- 引入含 γ-CD 的阳离子金属有机骨架 (CD-MOF) 中. 尽管 γ-CD tori 在 CD-HFs 固态超结构中的堆积排列与先前报道的 CD-MOFs 相同,但与之前报道的 CD-HFs 相比,CD-HFs 以较低的对称性和长方体空间群 P43212-结晶CD-MOF-1,由于CD-HF超结构中4-MS-阴离子的手性堆积,它具有I432空间群的立方晶胞。重要的是,CD-HF 具有与孔道相关的超微孔,与 CD-MOF-1 有显着偏差,这是由于 4-MS-阴离子的贡献,作为超分子挡板。在气体吸附-解吸实验中,CD-HF-1 在 195 K 时对 CO2 表现出 306 m2 g-1 的 Brunauer-Emmett-Teller (BET) 表面积,但在 77 K 时不吸收 N2,证实了孔隙率的差异CD-HF-1 和 CD-MOF-1 之间。此外,CD-HF-1 中的 4-MS- 阴离子可以与 OH- 阴离子交换,导致不可逆的单晶向单晶转变,配位金属离子重排。当 OH- 离子交换为 4-MS- 阴离子时,CD-MOF-1 中也观察到可逆转变,空间群从 I432 变为 R32。这种有机反阴离子共组装策略为构建混合框架开辟了新途径,这是现有的从头 MOF 组装方法无法实现的。
更新日期:2020-01-14
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