Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany.
Dalton Trans. 2013 Apr 14;42(14):4840-7. doi: 10.1039/c3dt32355b.
The metal–organic framework compound [Al(OH)(BDC-Br)] (1) (BDC-Br2− = 5-bromo-1,3-benzenedicarboxylate) denoted CAU-10-Br was synthesised under solvothermal reaction conditions. Its structure was successfully refined by Rietveld methods. The framework is based on the connection of infinite helical chains of cis-corner-sharing AlO6-polyhedra via BDC-Br2− ions. Thus non-intersecting parallel channels are formed, each periodically varying in diameter between 1.1 and 6.6 Å. Nevertheless 1 adsorbs CO2 at 298 K, while it is non-porous towards H2 and N2 at 77 K. Employing high-throughput (HT) methods we identified synthesis conditions that lead to the formation of mixed-linker MOFs with CAU-10 topology. Starting with a molar ratio H2BDC:H2BDC-Br = 3:1 we established a synthesis procedure for the partially bromo-functionalised mixed-linker-MOF [Al(OH)(BDC)0.8(BDC-Br)0.2] (2) denoted as CAU-10-H/Br. Starting with a molar ratio H2BDC-NH2:H2BDC-NO2 = 1:1 the partially NO2- and NH2-functionalised mixed-linker MOF [Al(OH)(BDC-NO2)0.55(BDC-NH2)0.23(BDC-NHCHO)0.22] (3) denoted as CAU-10-NO2/NH2 was synthesised, in which the NH2-groups were found to be partially formylated. The partial bromo-functionalisation in CAU-10-H/Br (2) leads to a lower sorption capacity in comparison with the parent structure CAU-10-H, while the pore accessibility is comparable. The incorporation of NO2-, NH2- and NHCHO-groups in CAU-10-NO2/NH2 (3) does not only affect the accessibility of the pores for N2, but results also in an increased capacity for H2 and CO2 in comparison with the parent structure CAU-10-NO2. The reproducibility of the synthesis procedures was tested regarding the composition of the MOFs and the resulting gas sorption properties. In 2 a molar fraction of (BDC)2− = 80 ± 2% is found, while in 3 a molar fraction of (BDC-NO2)2− = 55 ± 2% is observed. Starting from the molar ratio H2BDC:H2BDC-CH3 = 1:1 mixed linker MOFs denoted as CAU-10-H/CH3 (4) were also obtained. In contrast to 2 and 3 the molar ratios of BDC2−/BDC-CH32− and especially the sorption properties differ substantially for every batch. The compounds were further characterised by X-ray powder diffraction, thermogravimetric/elemental analysis, NMR/Vis/IR-spectroscopy, and gas sorption measurements.
金属-有机骨架化合物[Al(OH)(BDC-Br)]（1）（BDC-Br2−=5-溴-1,3-苯二甲酸酯）被命名为 CAU-10-Br，是在溶剂热反应条件下合成的。其结构通过 Rietveld 方法成功地进行了细化。该骨架基于通过 BDC-Br2−离子连接的顺式角共享 AlO6-多面体的无限螺旋链。因此，形成了非相交的平行通道，每个通道的直径在 1.1 和 6.6 Å之间周期性变化。尽管如此，1 在 298 K 下吸附 CO2，而在 77 K 下对 H2 和 N2 是非多孔的。采用高通量（HT）方法，我们确定了导致具有 CAU-10 拓扑结构的混合配体 MOF 形成的合成条件。从摩尔比 H2BDC:H2BDC-Br = 3:1 开始，我们建立了部分溴官能化混合配体 MOF [Al(OH)(BDC)0.8(BDC-Br)0.2]（2）的合成程序，称为 CAU-10-H/Br。从摩尔比 H2BDC-NH2:H2BDC-NO2 = 1:1 开始，部分 NO2-和 NH2-官能化的混合配体 MOF [Al(OH)(BDC-NO2)0.55(BDC-NH2)0.23(BDC-NHCHO)0.22]（3）被合成，其中发现 NH2-基团部分甲酰化。与母体结构 CAU-10-H 相比，CAU-10-H/Br（2）中的部分溴官能化导致吸附容量降低，而孔可及性相当。在 CAU-10-NO2/NH2（3）中引入 NO2-、NH2-和 NHCHO-基团不仅影响 N2 的孔可及性，而且还导致与母体结构 CAU-10-NO2 相比，H2 和 CO2 的容量增加。对合成程序的重现性进行了测试，涉及 MOF 的组成和所得气体吸附性能。在 2 中发现（BDC）2−的摩尔分数为 80±2%，而在 3 中发现（BDC-NO2）2−的摩尔分数为 55±2%。还获得了摩尔比 H2BDC:H2BDC-CH3 = 1:1 的混合配体 MOF，标记为 CAU-10-H/CH3（4）。与 2 和 3 相比，BDC2−/BDC-CH32−的摩尔比，特别是吸附性能，每个批次都有很大差异。通过 X 射线粉末衍射、热重/元素分析、NMR/Vis/IR 光谱和气体吸附测量对化合物进行了进一步表征。
