MRI: Acquisition of a Variable Field (X-, Q-band) Pulsed EPR Spectrometer for Research and Training

在重大研究仪器计划(MRI)的这一奖项和化学研究仪器计划(CRIF)的支持下，加州理工学院的Jonas Peters教授、Theodor Agapie教授和同事们获得了一台X、Q波段脉冲电子顺磁共振(EPR)光谱仪和相关附件，包括电子核双共振(Endor)。该仪器允许在各种领域进行研究，例如那些提供对具有未配对电子的生物相关物种如何行为的洞察。一般来说，EPR光谱仪可以提供有关分子和固态材料的几何和电子结构的详细信息。它还可以用来获得有关自由基寿命的信息，自由基是参与有价值的化学转化的短暂、高活性物种，以及启动病理性肿瘤生长的信息。在标准的恩多尔实验中，样品被置于磁场中，然后用微波和射频依次照射。然后，通过监测饱和电子顺磁共振转变的极化变化来检测这些变化。这些研究影响了许多领域，从无机和有机分子的合成到新型固态材料的开发，再到具有磁性和生物意义的化合物。该仪器是加州理工大学本科生和研究生阶段研究和教学中不可或缺的一部分，其灵感来自于正在进行的研究。此外，调查人员还从该机构以外的区域发现了大量感兴趣的用户，并确定了对EPR/脉冲EPR实践讲习班的极大热情，该讲习班预计将扩大区域用户基础。该奖项旨在加强各级的研究和教育，特别是在以下领域：(A)铁钼辅助因子(FeMoco)和固氮；(B)铁介导的固氮模型；(C)光合作用中的放氧复合体；(D)镍催化的交叉偶联；(E)光氧化还原催化；(F)具有自旋活性的金属二氢和金属氢化物物种；(G)催化中的金属腈；(H)用于碳-碳偶联的C1和C2前体；以及(I)用于膜和分泌蛋白生物发生研究的定点定向自旋标记。

With this award from the Major Research Instrumentation Program (MRI) and support from the Chemistry Research Instrumentation Program (CRIF), Professors Jonas Peters, Theodor Agapie and colleagues from the California Institute of Technology aquire an X-, Q-band pulsed electron paramagnetic resonance (EPR) spectrometer and related accessories including electron nuclear double resonance (ENDOR). This instrument allows research in a variety of fields such as those that provide insight on how biologically relevant species with unpaired electrons behave. In general, an EPR spectrometer yields detailed information on the geometric and electronic structure of molecular and solid state materials. It may also be used to obtain information about the lifetimes of free radicals, short-lived, highly reactive species involved in valuable chemical transformations as well as the initiation of pathological tumor growth. In a standard ENDOR experiment, a sample is placed in a magnetic field and irradiated sequentially with a microwave followed by radio frequency. The changes are then detected by monitoring variations in the polarization of the saturated electron paramagnetic resonance transition. These studies impact a number of areas, from the synthesis of inorganic and organic molecules to the development of new solid state materials to compounds of magnetic and biological interest. Employing examples inspired from ongoing research, this instrument is an integral part of research and teaching at the undergraduate and graduate levels at Caltech. Additionally, the investigators have identified a significant number of interested users from the area outside of this institution and also identified a lot of enthusiasm for a hands-on workshop on EPR/pulsed-EPR that is expected to grow the regional user base.The award is aimed at enhancing research and education at all levels, especially in areas such as: (a) the iron-molybdenum co-factor (FeMoco) and nitrogen fixation; (b) models of iron-mediated nitrogen fixation; (c) oxygen-evolving complex in photosynthesis; (d) nickel-catalyzed cross-coupling; (e)photoredox catalysis; (f) spin-active metal-dihydrogen and metal-hydride species; (g) metallonitrenes in catalysis; (h) using C1 and C2 precursors for carbon-carbon couplings; and (i) site directed spin labeling (SDSL) for the study of biogenesis of membrane and secretory proteins.