Key Laboratory of Functional Polymer Materials, Ministry of Education, College of Chemistry, Nankai University, Tianjin, People's Republic of China.
J Phys Chem A. 2012 Jan 26;116(3):979-84. doi: 10.1021/jp2078902. Epub 2012 Jan 17.
The structure and dynamic behavior of mobile components play a significant role in determining properties of solid materials. Herein, we propose a novel real-time spectrum-editing method to extract signals of mobile components in organic solids on the basis of the polarization inversion spin exchange at magic angle (PISEMA) pulse sequence and the difference in (13)C T(1) values of rigid and mobile components. From the dipolar splitting spectrum sliced along the heteronuclear dipolar coupling dimension of the 2D spectrum, the structural and dynamic information can be obtained, such as the distances between atoms, the dipolar coupling strength, the order parameter of the polymer backbone chain, and so on. Furthermore, our proposed method can be used to achieve the separation of overlapped NMR signals of mobile and rigid phases in the PISEMA experiment. The high efficacy of this 2D NMR method is demonstrated on organic solids, including crystalline L-alanine, semicrystalline polyamide-6, and the natural abundant silk fibroin.
在确定固体材料的性质方面，移动组件的结构和动态行为起着重要作用。在此，我们基于魔角偏振翻转交换（PISEMA）脉冲序列和刚性与移动组件之间的（13）C T1 值差异，提出了一种新的实时谱编辑方法，以从二维（2D）谱的异核偶极耦合维度上沿其切取的偶极分裂谱中提取有机固体中移动组件的信号。从该偶极分裂谱中，可以获得结构和动态信息，例如原子之间的距离、偶极耦合强度、聚合物主链链的有序参数等。此外，我们提出的方法可用于实现 PISEMA 实验中移动相和刚性相重叠 NMR 信号的分离。该二维（2D）NMR 方法在包括结晶 L-丙氨酸、半晶态聚酰胺-6 和天然丰富的丝素蛋白在内的有机固体中展现了其高效性。
