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: 0809985
• 负责人: David Tierney
• 金额: $ 34.5万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0809985&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.

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-r​​ay absorption spectroscopy and paramagnetic resonance (PMR), simultaneously applying mutli-frequency electron paramagnetic resonance (EPR, 9 and 35 GHz),电子 - 核双重共振（Endor，9和35 GHz）和核磁共振（NMR，H = 100、300和500 MHz； NMRD，h。175 MHz），以定义在高型螺旋co（II）系统中广泛的高型阵列中电子高细胞相互作用的场和温度依赖性。电子松弛将通过依赖于场和温度的NMR松弛以及NMR分散（NMRD）详细研究。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。该系统模仿钴级金属化学中的两个关键结构元素：共核和二半半胱氨酸。将研究一系列的BIS-（BP）和Tris-（TP）吡唑基孔酸酯络合物，以模仿金属 - 抗二碱的相互作用。 均质和杂色复合物允许制备4，5或6坐标的中性HS CO（II）复合物，所有配合物都具有相同的供体集。将检查MN（II）和V（II）的复合物，该复合物将检查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。 建模共同相互作用的努力将涉及常见的烷基和芳烃小分子化学，并将检查甲基转移反应，为评估功能模型系统中的CO-for-ZN替换提供独特的机会。为了弥合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。提出了PMR研究，该研究将极大地提高我们对钴硫键的了解。少数派在大学范围内，占学生群体的49％。其中，有28％的学生是西班牙裔，11％是美国原住民。目前，宣布的化学本科专业的总数为110，其中46％来自传统代表性不足的群体。研究生计划和Tierney Labs的种族细分也是如此多样化。 PI重新开发了高级，本科生的合成和表征实验室，其实验是从以前和当前的研究经验的结果中得出的，并将纳入从拟议的研究材料的拟议研究中得出的新发展。