Doan Peter E, Drena Alex, Sharma Ajay, Hoffman Brian M
Department of Chemistry, Northwestern University, Evanston IL, USA 60626.
Appl Magn Reson. 2024 Sep;55(9):969-986. doi: 10.1007/s00723-024-01680-w. Epub 2024 Jul 22.
We examine the Electron Paramagnetic Resonance (EPR) and Electron-Nuclear Double Resonance (ENDOR) spectroscopy of three quite distinct high-spin Mn(II) systems and describe experimental techniques and methods of analysis that are useful in their study. We demonstrate that this S=5/2 metal center provides useful orientation-selection through the Zero-Field Splitting (ZFS) tensor that enables determination of a C hyperfine-coupling tensor with extremely small hyperfine interaction. We also demonstrate that Mims suppression effects can be used in concert with orientation-selection to edit complex H ENDOR patterns that can be produced by even a 'simple' center with a single Mn(II). We develop a perturbation-based approach to understanding second-order shifts in Mn(II) ENDOR responses that occur in systems with intermediate ZFS values, and show that these shifts can be used to estimate the values of the ZFS tensors.
我们研究了三种截然不同的高自旋锰（II）体系的电子顺磁共振（EPR）和电子-核双共振（ENDOR）光谱，并描述了对其研究有用的实验技术和分析方法。我们证明，这个S = 5/2金属中心通过零场分裂（ZFS）张量提供了有用的取向选择，该张量能够确定具有极小超精细相互作用的碳超精细耦合张量。我们还证明，米姆斯抑制效应可以与取向选择协同使用，以编辑复杂的氢ENDOR模式，即使是具有单个锰（II）的“简单”中心也可能产生这种模式。我们开发了一种基于微扰的方法来理解在具有中等ZFS值的体系中锰（II） ENDOR响应中的二阶位移，并表明这些位移可用于估计ZFS张量的值。
