Synthetic Models of the Oxygen Evolving Complex of Photosystem II

通过这一奖项，化学部的生命过程化学项目资助阿加皮博士研究锰和钙离子簇的结构如何影响它们将水转化为分子氧的能力。这项研究可以提供有关植物光合作用的信息，光合作用是植物捕捉太阳能并利用它转化二氧化碳和水分子的过程，这些分子是其他更复杂的分子，比如它们生存所需的糖。在植物中，水转化为氧气是由一个锰和钙团簇催化的，阿加皮博士在他的实验室里合成了类似物。阿加皮博士和他的团队研究了这些人工类似物与自然系统的反应。他的研究结果为如何从不同的金属离子中制造催化剂提供了信息，这些催化剂可能会用于人工光合作用。这些研究使研究生能够获得复杂配位化合物的一系列合成和分析表征技术方面的专业知识，并为21世纪的STEM职业生涯做准备。阿加皮博士的研究实验室对放氧复合体(OEC)的一系列锰团簇模型进行了结构-反应性研究。OEC负责在光系统II(PSII)中将水转化为氧，PSII是一种蛋白质复合体，可以从阳光中捕获光子，并使用它们来产生植物化学反应所需的电子。在人工光合作用中，水到氧气的转化是能量储存和转化的重要环节。将水转化为氧气会产生还原当量，用于将二氧化碳等低能量前体转化为高能量前体，如糖(在生物系统中)或液态碳氢化合物(在人工系统中是一个有吸引力的目标)。尽管PSII的研究取得了重大进展，但水氧化的原子水平机制仍在争论中。在初步结果的支持下，进行了机理和反应性研究，这些结果表明可以获得与OEC和所需的O-O键形成化学相关的结构基序。制备了展示悬挂金属图案的OEC的簇状模型。在这些簇中，金属中心是有位置区分的，这允许系统地评估远程金属对其性质的影响。讨论了星团几何、组成、氧化还原状态和自旋态对反应性和光谱的影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Agapie to study the way in which the structure of clusters of manganese and calcium ions affect their ability to convert water into molecular oxygen. This research can provide information about the chemical reactions that underscores photosynthesis in plants, the process by which the plants capture solar energy and use it to transform carbon dioxide and water molecules in other, more complex molecules like sugars needed for their survival. The conversion of water to oxygen is catalyzed in plants by a manganese and calcium cluster and Dr. Agapie synthesizes analogues in his lab. Dr. Agapie and his team study the reactions of these artificial analogues in comparison with the natural systems. The results of his research provide information on how to build catalysts from different metal ions that may be used in artificial photosynthesis. These studies allow graduate students to acquire expertise in a range of synthetic and analytical characterization techniques for complex coordination compounds and to prepare for 21st century STEM careers. Dr. Agapie's research lab performs structure-reactivity studies of a series of manganese cluster models of the Oxygen Evolving Complex (OEC). OEC is responsible for converting water into oxygen in Photosystem II (PSII), a protein complex that captures photons from sunlight and uses them to create electrons needed in chemical reactions in plants. The conversion of water to dioxygen is important for energy storage and conversion in artificial photosynthesis. The transformation of water into oxygen generates reducing equivalents used to transform low-energy precursors, such as carbon dioxide into energy-rich ones, such as sugars (in biological systems) or liquid hydrocarbons (an attractive target in artificial systems). Despite significant advances in the study of PSII, the atomic level mechanism of water oxidation continues to be debated. Supported by preliminary results that demonstrate that structural motifs relevant to the OEC and desired O-O bond formation chemistry can be accessed, mechanistic and reactivity studies are performed. Cluster models of the OEC displaying the dangler metal motif are prepared. In these clusters, the metal centers are site differentiated, which allows for systematic evaluation of the effect of remote metals on their properties. The effect of the cluster geometry, composition, redox state and spin state, on reactivity and spectroscopy are addressed.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.