Fundamentals of Chemistry that Guide Formation of Sulfur-bridged Bi- and Multi-metallic Molecular Units

指导硫桥双金属和多金属分子单元形成的化学基础

• 批准号: 2102159
• 负责人: Marcetta Darensbourg
• 金额: $ 50万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2102159&HistoricalAwards=false
• 关键词: Fundamentals; Chemistry; Guide; Formation; Sulfur

With the support of the Chemical Synthesis program in the Division of Chemistry, Professor Marcetta Y. Darensbourg and coworkers of Texas A&M University will study molecules that inform chemists about Nature’s choice of sulfur to connect metals in structures that perform as catalysts in biology. In contrast to the heavy, precious/expensive metals such as platinum and rhodium that one might find in the catalytic converter of an automobile, Nature must rely on the natural abundance distribution of metals on earth. Consequently, earth-abundant metals such as iron, nickel, and manganese are taken up in molecular motifs that utilize cooperativity between metals. In addition, their strategic positioning within a molecular environment, and timing of delivery of reactants and release of products, renders incredible reactions that are facile at ordinary temperatures and pressures. The importance of connections is vital to these molecular-binding motifs. Sulfur is a key ingredient in metalloenzymes that perform some of the most fundamental reactions of life. Examples include catalysts that facilitate hydrogen production, carbon dioxide reduction, and nitrogen conversion. How these molecular catalysts, imbedded in protein folds, work remains largely a mystery that inspires chemists to search for clues in small, well characterized molecules. This work will target connections between nickel and iron in new synthetic molecules outfitted with “reporter” molecules that indicate reactive centers. The Darensbourg team will analyze their structures and properties, monitoring changes as electrons are added or removed one by one. They will search for and characterize products of catalysis of proton reduction or synthesis. These fundamental studies are ideal for training graduate and undergraduate students and coworkers to recognize and appreciate sciences that connect biology and chemistry. With the support of the Chemical Synthesis program in the Division of Chemistry, Professor Marcetta Y. Darensbourg of Texas A&M University will establish a synthetic chemistry plan that targets an improved understanding of bimetallic constructs prevalent in redox-processing enzymes including diiron and nickel-iron hydrogenases. The overall goal is to understand how two (or multiple) abundant first-row metals share the burden of 2-electron transformations, whereby obviating the need for noble metals in natural catalysis and organic synthesis. Questions arise from the ubiquitous mediation by sulfur as a bridge between metal complexes that have redox activity either at the metal or the ligands, and how substrates are positioned on the reactive centers. Two principal classic “non-innocent” redox-active ligands will be engaged for this work, namely nitric oxide (NO) and dithiolenes. The Darensbourg group is developing NO-containing metallodithiolate ligands as bidentate S-donors to a transition metal Lewis acid receiver for examination of properties of the redox levels in a diiron trinitrosyl. The team proposes to monitor the electronic and vibrational coupling between two S-bridged iron as affected by redox level of the diiron complex using N-15 isotopic labelling and two-dimensional infrared spectroscopy. In addition, the effect of redox level on the observed scrambling of the NO ligand between the two irons is expected to inform our understanding of communications between metals in the sulfur-bridged bimetallics. The concerted effect of two different types of delocalization ligands with a nickel-dithiolene as receiver to the metallodithiolates will offer an opportunity to explore inter- and/or intramolecular magnetic quenching and electronic coupling. Studies of the properties of the new bimetallics will improve our understanding of multimetallic bioinorganic enzyme active sites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在化学系化学合成项目的支持下，德克萨斯农工大学的 Marcetta Y. Darensbourg 教授和同事将研究分子，让化学家了解大自然选择硫来连接在生物学中充当催化剂的结构中的金属。对于汽车催化转化器中可能发现的重、贵/贵金属，例如铂和铑，大自然必须依赖于金属的自然丰度分布经过测试，地球上丰富的金属（例如铁、镍和锰）被吸收到利用金属之间的协同作用的分子基序中，此外，它们在分子环境中的战略定位以及反应物的传递和产物的释放的时间，连接的重要性对于这些分子结合基序至关重要，硫是进行生命中一些最基本反应的金属酶的关键成分。包括促进氢气产生、二氧化碳还原和氮气转化的催化剂，这些嵌入蛋白质折叠中的分子催化剂如何发挥作用在很大程度上仍然是一个谜，这激励化学家寻找特征明确的小分子的线索。配备有“报告”分子的新合成分子中的镍和铁可以指示反应中心，达伦斯堡团队将分析它们的结构和性质，监测电子逐一添加或删除时的变化，他们将寻找并表征催化产物。在化学系化学合成项目的支持下，这些基础研究非常适合培训研究生和本科生及同事认识和欣赏连接生物学和化学的科学。德克萨斯农工大学将制定一项合成化学计划，旨在加深对氧化还原加工酶（包括二铁和镍铁氢化酶）中普遍存在的双金属结构的了解，总体目标是了解两种（或或多种）如何结合。多种）丰富的第一行金属分担2电子转化的负担，因此消除了自然催化和有机合成中对贵金属的需求，而硫作为具有氧化还原活性的金属配合物之间的桥梁的普遍存在引起了问题。这项工作将涉及金属或配体，以及底物如何定位在反应中心上，即一氧化氮。 Darensbourg 小组正在开发含 NO 的金属二硫醇配体，作为过渡金属路易斯酸受体的二齿 S 供体，用于检查三亚硝基二铁的氧化还原水平的性质。使用 N-15 同位素标记和二维红外光谱分析受二铁络合物氧化还原水平影响的两个 S 桥铁之间的耦合。此外，氧化还原水平对观察到的两种铁之间NO配体的扰乱的影响预计将有助于我们了解硫桥双金属中金属之间的通信，两种不同类型的离域配体与镍的协同作用。二硫醇作为金属二硫醇盐的接收体将为探索分子间和/或分子内磁猝灭和电子耦合研究新型双金属的性能提供机会。提高我们对多金属生物无机酶活性位点的理解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。