Characterization of the metal-organic framework compound Cu3(benzene 1,3,5-tricarboxylate)2 by means of 129Xe nuclear magnetic and electron paramagnetic resonance spectroscopy
Characterization of the metal-organic framework compound Cu3(benzene 1,3,5-tricarboxylate)2 by means of 129Xe nuclear magnetic and electron paramagnetic resonance spectroscopy
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DOI：
10.1021/jp063074r
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发表时间：
2006-10-19
影响因子：
3.3
通讯作者：
Kaskel, Stefan
中科院分区：
文献类型：
--
作者：
Boehlmann, Winfried;Poeppl, Andreas;Kaskel, Stefan
吸附氙的129 NMR测量首次被证明是表征金属有机骨架Cu-3（BTC）（2）（H2O）（3）（BTC =苯1，3，5-三羧酸酯）的孔隙率和性质的合适工具。NMR实验在室温和宽范围的氙压下进行，并在两个不同的合成Cu-3（BTC）（2）样品。129 NMR结果表明，根据合成途径的不同，在两个不同孔径的孔中，氙原子的两种快速交换产生了一个或两个信号。氙和乙烯的共吸附实验表明，氙原子更喜欢填充材料的较大孔隙，因为较小的孔隙被合成过程中的残留分子和另外吸附的乙烯所占据。除了核磁共振实验的一系列电子顺磁共振（EPR）测量进行估计的状态，铜有强烈的影响吸附氙的化学位移。EPR实验表明，互连的铜二聚体之间的自旋交换发生在Cu-3（BTC）（2）框架中的BTC连接分子上。
Xe-129 NMR measurements of adsorbed xenon are shown for the first time to be a suitable tool to characterize the porosity and the properties of the metal-organic framework Cu-3(BTC)(2)(H2O)(3) (BTC = benzene 1,3,5-tricarboxylate). The NMR experiments are performed at room temperature and over a wide range of xenon pressure and on two different synthesized Cu-3(BTC)(2) samples. Xe-129 NMR results reveal that in dependence on the kind of the synthesis pathway either one or two signals are observed which can be attributed to two kinds of fast exchange of xenon atoms in two pores with different pore sizes. Coadsorption experiments of xenon and ethylene demonstrate that the xenon atoms prefer to fill the greater pores of the material because the smaller pores are occupied with residual molecules from the synthesis procedure and additionally adsorbed ethylene. Besides the NMR experiments a series of electron paramagnetic resonance (EPR) measurements are performed to estimate the state of copper having a strong influence on the chemical shift of the adsorbed xenon. The EPR experiments demonstrate that spin exchange between the interconnected copper dimers is taking place across the BTC linker molecules in the Cu-3(BTC)(2) framework.