The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900 Israel.
Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States.
J Phys Chem B. 2020 Jul 23;124(29):6225-6235. doi: 10.1021/acs.jpcb.0c03687. Epub 2020 Jul 14.
The microscopic-order-macroscopic-disorder (MOMD) approach for NMR lineshape analysis has been applied to the University of Windsor Dynamic Materials (UWDM) of types 1, 2, α-3, β-3, and 5, which are metal-organic frameworks (MOFs) comprising mobile mechanically interlocked molecules (MIMs). The mobile MIM components are selectively deuterated crown ether macrocycles - 24C6, 22C6, and B24C6. Their motion is described in MOMD by an effective/collective dynamic mode characterized by a diffusion tensor, , a restricting/ordering potential, , expanded in the Wigner rotation matrix elements, , and features of local geometry. Experimental H lineshapes are available over 220 K (on average) and in some cases 320 K. They are reproduced with axial , given by the terms and , and established local geometry. For UWDM of types 1, β-3, and 5, where the macrocycle resides in a relatively loose space, is in the 1-3 , in the (1.0-2.5) × 10 s, and in the (0.4-2.5) × 10 s range; the deuterium atom is bonded to a carbon atom with tetrahedral coordination character. For UWDM of types 2 and α-3, where the macrocycle resides in a much tighter space, a substantial change in the symmetry of and the coordination character of the H-bonded carbon are detected at higher temperatures. The activation energies for and are characteristic of each system. The MOMD model is general; effective/collective dynamic modes are treated. The characteristics of motion, ordering, and geometry are physically well-defined; they differ from case to case in extent and symmetry but not in essence. Physical clarity and consistency provide new insights. A previous interpretation of the same experimental data used models consisting of collections of independent simple motions. These models are specific to each case and temperature. Within their scope, generating consistent physical pictures and comparing cases are difficult; possible collective modes are neglected.
用于 NMR 线宽分析的微观-宏观-无序 (MOMD) 方法已应用于温莎大学动态材料 (UWDM) 1 型、2 型、α-3 型、β-3 型和 5 型，这些材料是由可移动的机械互锁分子 (MIM) 组成的金属有机骨架 (MOF)。可移动的 MIM 成分是选择性氘化的冠醚大环 - 24C6、22C6 和 B24C6。它们的运动在 MOMD 中由以扩散张量 、 为特征的有效/集体动态模式来描述， 是在 Wigner 旋转矩阵元素 中展开的限制/有序势， 并具有局部几何特征。实验 H 线宽可在 220 K（平均）以上，在某些情况下可达 320 K。它们通过轴向 来重现， 由项 和 给出，以及已建立的局部几何形状。对于 UWDM 1 型、β-3 型和 5 型，大环位于相对宽松的空间中， 在 1-3 范围内， 在（1.0-2.5）×10 s 范围内， 在（0.4-2.5）×10 s 范围内；氘原子与具有四面体配位特征的碳原子键合。对于 UWDM 2 型和 α-3 型，大环位于更紧凑的空间中，在较高温度下检测到 和氢键合碳原子的对称性以及配位特征发生了实质性变化。 和 的活化能是每个系统的特征。MOMD 模型是通用的；处理有效/集体动态模式。运动、有序和几何的特征在物理上是明确定义的；它们在程度和对称性上因情况而异，但在本质上没有区别。物理清晰度和一致性提供了新的见解。对相同实验数据的先前解释使用了由独立简单运动集合组成的模型。这些模型是特定于每个案例和温度的。在其范围内，生成一致的物理图像和比较案例是困难的；可能的集体模式被忽略了。
