Meyer Andreas, Schiemann Olav
Institute of Physical and Theoretical Chemistry, University of Bonn , Wegelerstr. 12, Bonn, Germany.
J Phys Chem A. 2016 May 26;120(20):3463-72. doi: 10.1021/acs.jpca.6b00716. Epub 2016 May 17.
A homoleptic bisnitroxide complex of manganese(II) was synthesized as a model system for EPR spectroscopic distance determinations involving high-spin metal ions and more than one distance. The performance of the RIDME experiment is compared with that of the more frequently used PELDOR experiment. It is shown that the PELDOR experiment yields both distances, Mn(II)-nitroxide and nitroxide-nitroxide, and that they can be separated to a certain extent, whereas the RIDME experiment yields only the Mn(II)-nitroxide distance. Both pulse sequences yield artifacts, either due to multispin effects or higher electron-spin transitions. Orientation selection is mostly introduced by the nitroxide signal and can be averaged out by variation of the observer field in the RIDME experiment. Thus, both methods might be used complementarily to obtain a reliable picture of an unknown system.
合成了一种锰（II）的同配双氮氧络合物，作为用于电子顺磁共振光谱距离测定的模型系统，该测定涉及高自旋金属离子和多个距离。将旋转回波双量子相干（RIDME）实验的性能与更常用的脉冲电子双共振（PELDOR）实验的性能进行了比较。结果表明，PELDOR实验能得出锰（II）-氮氧和氮氧-氮氧这两个距离，并且它们在一定程度上可以分离，而RIDME实验仅能得出锰（II）-氮氧距离。由于多自旋效应或更高的电子自旋跃迁，这两种脉冲序列都会产生伪像。取向选择主要由氮氧信号引入，并且在RIDME实验中可以通过改变观测场将其平均掉。因此，这两种方法可以互补使用，以获得未知系统的可靠图像。
