NMR and X-ray Study Revealing the Rigidity of Zeolitic Imidazolate Frameworks
NMR and X-ray Study Revealing the Rigidity of Zeolitic Imidazolate Frameworks
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DOI：
10.1021/jp303907p
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发表时间：
2012-06-21
影响因子：
3.7
通讯作者：
Garcia-Garibay, Miguel A.
中科院分区：
文献类型：
--
作者：
Morris, William;Stevens, Caitlin J.;Garcia-Garibay, Miguel A.
报道了分子筛咪唑骨架-8(ZIF-8)的核磁共振弛豫研究和光谱测量。空气中ZIF-8分子筛的主要核自旋-晶格弛豫(T-1)机制来自大气中的顺磁分子氧。C-13T-1测定表明，氧主要与咪唑环相互作用，而不是与甲基取代基相互作用。在含有未取代环ZIF-4的ZIF中也观察到了类似的松弛行为。用单晶X射线衍射法研究了ZIF-8分子筛在100-298K温度范围内的热椭球，进一步证实了ZIF-8骨架的刚性。这些结果突出了一个刚性的ZIF骨架，并与基于苯二甲酸酯连接基团的动态金属-有机骨架形成对比，后者的松弛反映了苯二甲酸根的动力学。
NMR relaxation studies and spectroscopic measurements of zeolitic imidazolate framework-8 (ZIF-8) are reported. The dominant nuclear spin-lattice relaxation (T-1) mechanism for ZIF-8 in air arises from atmospheric paramagnetic molecular oxygen. The C-13 T-1 measurements indicate that the oxygen interacts primarily with the imidazolate ring rather than the methyl substituent. Similar relaxation behavior was also observed in a ZIF with an unsubstituted ring, ZIF-4. Single-crystal X-ray diffraction was used to provide data for the study of the thermal ellipsoids of ZIF-8 at variable temperatures from 100 to 298 K, which further confirmed the rigid nature of this ZIF framework. These results highlight a rigid ZIF framework and are in contrast with dynamic metal-organic frameworks based on benzenedicarboxylate linking groups, for which the relaxation reflects the dynamics of the benzenedicarboxylate moiety.