Department of Electronic Science, Fujian Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, PR China.
J Magn Reson. 2011 Aug;211(2):162-9. doi: 10.1016/j.jmr.2011.05.008. Epub 2011 May 23.
Recently, a method based on intermolecular multiple quantum coherences (iMQCs) has been proposed to obtain high-resolution 2D COSY spectra in inhomogeneous fields via 3D acquisitions. However, the very long acquisition time prevents its practical application. To overcome this shortage, the Hadamard technique was applied for the iMQC method in this paper. For the new pulse sequence, the direct frequency-domain excitation is used in the first indirect detection dimension, so the 3D acquisition was replaced by an array of 2D acquisitions. The acquisition time can be reduced to 10 min. The resulting spectra retain useful structural information including chemical shifts and multiplet patterns of J coupling even when the inhomogeneous line broadening leads to overlap of neighboring diagonal resonances in the conventional COSY spectrum. The experimental results are consistent with the theoretical predictions and computer simulations. The new sequence may provide a time-efficient way for the studies of chemical solution in inhomogeneous fields.
最近，提出了一种基于分子间多量子相干（iMQCs）的方法，通过 3D 采集在不均匀场中获得高分辨率的 2D COSY 谱。然而，非常长的采集时间使其无法实际应用。为了克服这一不足，本文将 Hadamard 技术应用于 iMQC 方法。对于新的脉冲序列，在第一间接检测维度中使用直接频域激发，因此 3D 采集被替换为一系列 2D 采集。采集时间可以减少到 10 分钟。即使在不均匀线宽导致常规 COSY 谱中相邻对角共振重叠的情况下，所得光谱仍保留有用的结构信息，包括化学位移和 J 耦合的多重峰模式。实验结果与理论预测和计算机模拟一致。新序列可能为不均匀场中化学溶液的研究提供一种高效的方法。
