The chemical shifts of protons depend not only on the properties of the solute molecule but also on the medium in which the solute resides. A series of β-lactams with various substitution patterns were synthesized to study aromatic-solvent-induced shifts (ASISs) in chloroform and benzene by using 1H NMR spectroscopy. The results agreed with those obtained by theoretical density functional theory calculations. The protons of the β-lactam ring are the most affected by the ASIS effect, and they tend to overlap due to the anisotropic effect of benzene.

中文翻译：

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在核磁共振波谱中使用芳香溶剂引起的位移来分析具有各种取代模式的 β-内酰胺的新方法

质子的化学位移不仅取决于溶质分子的性质，还取决于溶质所在的介质。合成了一系列具有各种取代模式的 β-内酰胺，以使用 1 H NMR 光谱研究氯仿和苯中的芳烃溶剂引起的位移 (ASIS)。结果与理论密度泛函理论计算得出的结果一致。β-内酰胺环的质子受ASIS效应影响最大，由于苯的各向异性效应，它们往往会重叠。