Integrated Paramagnetic Resonance of High-Spin Cobalt(II) Systems

高自旋钴(II)系统的集成顺磁共振

• 批准号: 0964806
• 负责人: David Tierney
• 金额: $ 24.97万
• 依托单位: Miami University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0964806&HistoricalAwards=false
• 关键词: Integrated; Paramagnetic; Resonance; Spin; Cobalt

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor David L. Tierney at the University of New Mexico to systematically investigate a library of model compounds by a combination of x-ray absorption spectroscopy and paramagnetic resonance (PMR), simultaneously applying mutli-frequency electron paramagnetic resonance (EPR, 9 and 35 GHz), electron-nuclear double resonance (ENDOR, 9 and 35 GHz) and nuclear magnetic resonance (NMR, H = 100, 300 and 500 MHz; NMRD, H . 1 75 MHz), to define the field- and temperature-dependence of electronnuclear hyperfine interactions in a broad array of high-spin Co(II) systems. Electronic relaxation will be examined in detail by field- and temperature-dependent NMR relaxation and by NMR dispersion (NMRD). The behavior of the model systems will guide spectroscopic studies of systems of unknown structure, where x-ray absorption spectroscopy (XAS) will provide additional, critical structural constraints. The systems mimic two key structural elements in the metallobiochemistry of cobalt: Co-Nhistidine and Co-Scysteine. A series of bis- (Bp) and tris- (Tp) pyrazolylborate complexes will be studied to emulate metal-histidine interactions. Homoleptic and heteroleptic complexes allow preparation of neutral hs Co(II) complexes that are 4-, 5- or 6-coordinate, all with the same donor set. Complexes of Mn(II) and V(II), defining the contributions of global symmetry and spin-orbit coupling to the observed electron-nuclear interactions, will be examined. Efforts to model Co-Scys interactions will involve common alkyl- and arylthiolate small-molecule chemistry, and methyl transfer reactions will be examined, affording a unique opportunity to evaluate the Co-for-Zn substitution in a functional model system. To bridge the gap between small-molecule and metalloprotein studies, a set of de novo metal-binding peptides, designed to present cys4, cys3his and cys2his2 binding sites, will be studied. PMR studies are proposed that will greatly advance our knowledge of cobalt-sulfur bonding. Minority enrollment University-wide represents 49 % of the student body. Of this, 28% of the students are Hispanic and 11% are Native American. At the present time, the overall number of declared chemistry undergraduate majors is 110, with 46% of these coming from traditionally under-represented groups. The ethnic breakdown of both the graduate program and the Tierney labs are similarly diverse. The PI has re-developed the senior-level, undergraduate Synthesis and Characterization laboratory, with experiments developed out of results from previous and current research experience and will incorporate new developments derived from the proposed research into the course material.

该奖项属于无机、生物无机和有机金属化学项目，支持新墨西哥大学 David L. Tierney 教授的研究，通过结合 X 射线吸收光谱和顺磁共振 (PMR) 系统地研究模型化合物库，同时应用多频电子顺磁共振（EPR，9 和 35 GHz）、电子核双共振（ENDOR，9 和 35 GHz）和核磁共振（NMR，H = 100、300 和 500 MHz；NMRD，H 1 75 MHz），定义各种高自旋 Co(II) 系统中电子核超精细相互作用的场和温度依赖性。电子弛豫将通过场和温度相关的 NMR 弛豫以及 NMR 色散 (NMRD) 进行详细检查。模型系统的行为将指导未知结构系统的光谱研究，其中 X 射线吸收光谱 (XAS) 将提供额外的关键结构约束。该系统模拟了钴金属生物化学中的两个关键结构元素：Co-Nhistidine 和 Co-Systeine。将研究一系列双 (Bp) 和三 (Tp) 吡唑基硼酸盐复合物以模拟金属-组氨酸相互作用。 均配和杂配配合物可以制备 4、5 或 6 配位的中性 hs Co(II) 配合物，所有配合物均具有相同的供体组。将检查 Mn(II) 和 V(II) 的配合物，定义全局对称性和自旋轨道耦合对观察到的电子-核相互作用的贡献。 模拟 Co-Scys 相互作用将涉及常见的烷基硫醇盐和芳基硫醇盐小分子化学，并且将检查甲基转移反应，为评估功能模型系统中的 Co-Zn 取代提供了独特的机会。为了弥补小分子和金属蛋白研究之间的差距，将研究一组从头开始的金属结合肽，旨在呈现 cys4、cys3his 和 cys2his2 结合位点。 PMR 研究的提出将极大地增进我们对钴硫键合的了解。全校少数族裔入学人数占学生总数的 49%。其中，28% 的学生是西班牙裔，11% 是美国原住民。目前，申报的化学本科专业总数为110个，其​​中46%来自传统上代表性不足的群体。研究生项目和蒂尔尼实验室的种族划分也同样多样化。 PI 重新开发了高级本科生合成和表征实验室，其实验是根据以前和当前研究经验的结果开发的，并将将从拟议研究中获得的新进展纳入课程材料中。