A DOUBLE-QUANTUM FILTER FOR ROTATING SOLIDS
A DOUBLE-QUANTUM FILTER FOR ROTATING SOLIDS
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DOI：
10.1021/ja00260a001
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发表时间：
1987-12-23
影响因子：
15
通讯作者：
EARL, WL
中科院分区：
文献类型：
--
作者：
MEIER, BH;EARL, WL
证明了一个脉冲序列，它有效地激发双量子相干固体样品旋转的魔角。一个双量子滤波器使用该序列，并应用于13 C-标记的醋酸锌，以证明其有效性。甲基和羧基共振之间的13 C-13 C标量耦合被观察到，以及在这两个共振的中心产生的同素偶极哈密顿量的31 Hz的移位。我们还注意到，当两个耦合共振的自旋边带模式重叠时，碳的翻转跃迁会变得容易，从而导致谱线的显著加宽。在过去的几年里，n-量子滤波器在简化光谱和建立液态核磁共振中的碳-碳连接性方面证明了它们的有用性。更复杂的过滤技术，如拓扑过滤器，从复杂的混合物中只选择某些自旋系统，也已经被开发出来。8· 9这些实验已被证明对于有兴趣获得溶液中复杂分子结构的化学家非常有用。多量子实验，利用同向偶极耦合产生多量子
A pulse sequence is demonstrated which effectively excites double-quantum coherences in solid samples rotating at the magic angle. A double-quantum filter using this sequence is presented and applied to 13C-labeled zinc acetate to demonstrate its effectiveness. The 13C-13C scalar coupling between the methyl and carboxyl resonances was observed as well as a shift of 31 Hz in the center of both resonances arising from the homonuclear dipole Hamiltonian. It was also noted that when the spinning sideband patterns of the two coupled resonances overlap, carbon flip-flop transitions are facilitated, resulting in significant broadening of the spectral lines.During the last few years,«-quantum filters have proventheir usefulness in simplifying spectra and establishing carbon-carbon connectivities in liquid-state nuclear magnetic resonance. 1 11" 7 More sophisticated filtering techniques like topological filters which select only certain spinsystems out of a complicated mixture have also been developed. 8· 9 These experiments have proven very useful to chemists interested inobtaining the structure of complicated molecules in solution. Multiple-quantum experiments, using homonuclear dipole coupling to generate the multiple-quantum