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

该奖项在无机、生物无机和有机金属化学项目中支持新墨西哥大学David L. Tierney教授的研究，该研究通过x射线吸收光谱和顺磁共振（PMR）的组合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；嗯，嗯。1 75 MHz)，以定义在广泛的高自旋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核磁共振弛豫和核磁共振色散（NMRD）来详细研究。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。该系统模拟了钴金属生物化学中的两个关键结构元素：共组氨酸和共半胱氨酸。一系列双- (Bp)和三- (Tp)吡唑酸酯配合物将被研究以模拟金属-组氨酸的相互作用。同感和异感配合物允许制备具有相同供体集的4-、5-或6-配位的中性hs Co（II）配合物。Mn（II）和V（II）的配合物，定义了整体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，将被检查。模拟Co-Scys相互作用的努力将涉及常见的烷基和芳基硫酸盐小分子化学，甲基转移反应将被检查，提供一个独特的机会来评估在功能模型系统中的co -换锌取代。为了弥合小分子和金属蛋白研究之间的差距，将研究一组新的金属结合肽，旨在表达cys4， cys3his和cys2his2结合位点。提出的PMR研究将极大地推进我们对钴硫键的认识。少数族裔学生占整个大学学生总数的49%。其中，28%的学生是西班牙裔，11%是美洲原住民。目前，申报的化学本科专业的总人数为110人，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分布也同样多样化。PI重新开发了高级水平的本科合成和表征实验室，其实验是根据以前和当前的研究经验开发的，并将从拟议的研究中获得的新发展纳入课程材料。

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.