The catalytic power of an electric field depends on its magnitude and orientation with respect to the reactive chemical species. Understanding and designing new catalysts for electrostatic catalysis thus requires methods to measure the electric field orientation and magnitude at the molecular scale. We demonstrate that electric field orientations can be extracted using a two-directional vibrational probe by exploiting the vibrational Stark effect of both the C=O and C–D stretches of a deuterated aldehyde. Combining spectroscopy with molecular dynamics and electronic structure partitioning methods, we demonstrate that, despite distinct polarities, solvents act similarly in their preference for electrostatically stabilizing large bond dipoles at the expense of destabilizing small ones. In contrast, we find that for an active-site aldehyde inhibitor of liver alcohol dehydrogenase, the electric field orientation deviates markedly from that found in solvents, which provides direct evidence for the fundamental difference between the electrostatic environment of solvents and that of a preorganized enzyme active site.

电场的催化能力取决于其大小和相对于反应性化学物质的方向。因此，了解和设计用于静电催化的新型催化剂需要在分子尺度上测量电场方向和强度的方法。我们证明，通过利用氘代醛的 C=O 和 C-D 拉伸的振动斯塔克效应，可以使用双向振动探针提取电场方向。将光谱学与分子动力学和电子结构分配方法相结合，我们证明，尽管极性不同，但溶剂的作用相似，它们倾向于静电稳定大键偶极子，而牺牲小键偶极子的稳定性。相比之下，我们发现对于肝醇脱氢酶活性位点醛抑制剂，电场方向明显偏离溶剂中的电场方向，这为溶剂静电环境与预组织酶静电环境之间的根本差异提供了直接证据活跃站点。