The nuclear Overhauser effect (NOE) is a consequence of cross-relaxation between nuclear spins mediated by dipolar coupling. Its sensitivity to internuclear distances has made it an increasingly important tool for the determination of through-space atom proximity relationships within molecules of sizes ranging from the smallest systems to large biopolymers. With the support of sophisticated FT-NMR techniques, the NOE plays an essential role in structure elucidation, conformational and dynamic investigations in liquid-state NMR. The efficiency of magnetization transfer by the NOE depends on the molecular rotational correlation time, whose value depends on solution viscosity. The magnitude of the NOE between ¹H nuclei varies from +50% when molecular tumbling is fast to −100% when it is slow, the latter case corresponding to the spin diffusion limit. In an intermediate tumbling regime, the NOE may be vanishingly small. Increasing the viscosity of the solution increases the motional correlation time, and as a result, otherwise unobservable NOEs may be revealed and brought close to the spin diffusion limit. The goal of this review is to report the resolution of structural problems that benefited from the manipulation of the negative NOE by means of viscous solvents, including examples of molecular structure determination, conformation elucidation and mixture analysis (the ViscY method).

核 Overhauser 效应 (NOE) 是由偶极耦合介导的核自旋之间交叉松弛的结果。它对核间距离的敏感性使其成为确定从最小系统到大型生物聚合物分子大小范围内的空间原子邻近关系的越来越重要的工具。在复杂的 FT-NMR 技术的支持下，NOE 在液态 NMR 的结构解析、构象和动态研究中发挥着重要作用。NOE 的磁化转移效率取决于分子旋转相关时间，其值取决于溶液粘度。NOE 的大小介于¹H 核从分子翻滚快时的 +50% 变化到分子翻滚慢时的 -100%，后一种情况对应于自旋扩散极限。在中间翻滚状态下，NOE 可能小得令人难以置信。增加溶液的粘度会增加运动相关时间，因此，否则可能会发现无法观察到的 NOE，并使其接近自旋扩散极限。本综述的目的是报告通过粘性溶剂对负 NOE 进行操作而受益的结构问题的解决，包括分子结构测定、构象解析和混合物分析（ViscY方法）的示例。