Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR 6230, BP 92208, 2 rue de la Houssinière, F-44322 Nantes Cedex 03, France.
J Magn Reson. 2010 Jul;205(1):171-6. doi: 10.1016/j.jmr.2010.05.002. Epub 2010 May 10.
Ultrafast 2D NMR allows the acquisition of a 2D spectrum in a single scan. Still, a limitation affecting these experiments rests in their inability to cover large spectral ranges while preserving an acceptable resolution, due to limitations in gradient amplitudes and filter bandwidths. Various approaches relying on selective pulses have been recently proposed to overcome this drawback, by "shifting" resonances into arbitrary positions. However, these methods are associated with a number of drawbacks characterizing selective pulses. Here, we propose a new strategy to increase the spectral width accessible in the ultrafast dimension without degrading the resolution. This method leads to "folded-like" spectra along the ultrafast dimension. It does not require any selective pulse, and relies on suitably chosen gradients placed on each side of the mixing period. Our gradient-controlled folding method can be applied to almost any ultrafast 2D experiment, and appears to be particularly promising for heteronuclear 2D NMR. The results obtained on different compounds and pulse sequences (DQF-COSY, TOCSY, HSQC) are presented, highlighting the efficiency and the robustness of our method.
超快二维 NMR 允许在单次扫描中采集二维光谱。然而，这些实验受到限制，无法在保持可接受分辨率的同时覆盖大的光谱范围，这是由于梯度幅度和滤波器带宽的限制。最近提出了各种依赖于选择性脉冲的方法来克服这一缺点，通过将共振“移位”到任意位置。然而，这些方法与选择性脉冲的一些缺点有关。在这里，我们提出了一种新的策略，即在不降低分辨率的情况下增加超快维度上可访问的光谱宽度。该方法导致超快维度上出现“折叠样”光谱。它不需要任何选择性脉冲，而是依赖于在混合周期的每一侧适当选择的梯度。我们的梯度控制折叠方法可应用于几乎任何超快二维实验，对于异核二维 NMR 尤其有前途。呈现了在不同化合物和脉冲序列（DQF-COSY、TOCSY、HSQC）上获得的结果，突出了我们方法的效率和鲁棒性。
