CAREER: SusChEM: Metal Complexes with Pendant Proton Relays for Small Molecule Activation

CHE-1555387职业生涯：与悬挂式质子继电器的金属络合物用于小分子激活；南加州大学斯马兰达·C·马里内斯库(Smaranda C.Marinescu)直接从阳光中获取的能源是一种有吸引力的能源，可以满足全球对电力的需求，对环境的影响最小。为了利用这一几乎取之不尽的能源，首先需要解决太阳能捕获、储存和分配方面的几个重要问题，以便利用太阳辐射来满足全球能源需求。一种很有希望的方法是利用太阳能驱动化学反应，产生容易储存的燃料。二氧化碳(CO2)是燃烧化石燃料和其他工业过程中产生的令人不快的“温室气体”，它可能是太阳能催化生产碳氢燃料的一种丰富、经济的原料。在自然光合作用生物系统的启发下，斯马兰德拉·马里内斯库博士正在为这一过程开发分子催化剂。催化剂结构特别设计了能够活化二氧化碳的氢键骨架。该项目的研究目标是设计和合成由负电荷或中性分子片段(称为配体)支撑的第一排过渡金属催化剂络合物，这些分子片段能够提供化学反应所需的质子，并使用这些金属-配体络合物将二氧化碳转化为CO，这是激活温室气体形成碳氢化合物的第一步。这项研究在以高效和可储存的方式发展获得太阳能方面以及在从环境中消除二氧化碳从而将有害废物转化为有用资源方面都具有更广泛的社会影响。该项目还在满足将研究和教育活动结合在一起的职业具体标准方面产生了更广泛的影响，这使当地初中/高中的学生和教师都参与了与能源有关的项目和教育经验。Marinescu博士还在为本科生、研究生和博士后水平的女性制定指导计划，以增加这一代表不足的群体在科学领域的参与。在化学系化学催化项目的资助下，南加州大学化学系的斯马兰德拉·马里内斯库教授正在合成几个大环氨基吡啶配合物，并评估它们对二氧化碳还原的催化性能。初步研究表明，含NH基团的钴配合物是CO2还原为CO的有效电催化剂，具有良好的法拉第效率。相比之下，叔胺与钴的络合物并不是有效的二氧化碳还原催化剂，这表明仲胺的氨基的存在是催化反应的关键。进行化学计量学研究，以检测和表征催化循环中的拟议中间体。对所制备的催化剂进行了结构、电化学和光谱研究，以了解它们的化学反应活性。这些基础研究进一步加深了对氢键如何促进二氧化碳的减少和帮助开发使用廉价金属的实用催化剂的基本理解。此外，还有几个更广泛的影响直接与改善和多样化年轻科学家对化学感兴趣和参与的渠道有关。教育部分与能源和催化应用相结合，面向初中/高中学生和教师。Marinescu博士还在为本科生、研究生和博士后水平的女性制定指导计划，以增加这一代表性不足的群体在STEM领域的参与。

CHE-1555387 CAREER: Metal Complexes with Pendant Proton Relays for Small Molecule Activation; Smaranda C. Marinescu, University of Southern California (USC)Energy harvested directly from sunlight is an attractive source for filling the global need for power with minimal environmental impact. To avail ourselves of this practically inexhaustible source, several important problems in solar energy capture, storage, and distribution need first to be met in order to harness solar radiation to satisfy global energy demand. One promising method is the use of solar energy to drive chemical reactions that produce easily stored fuels. Carbon dioxide (CO2), the undesirable "greenhouse gas" byproduct of burning fossil fuels and other industrial processes, is potentially an abundant, economic feedstock for solar-driven catalysis to produce hydrocarbon fuels. With inspiration from natural photosynthetic biological systems, Dr. Smarandra Marinescu is developing molecular catalysts for this process. The catalyst architecture is specifically designed with a hydrogen-bonded framework capable of CO2 activation. The research goals of this project are to design and synthesize catalyst complexes of first-row transition metals supported by negatively-charged or neutral molecular fragments (called ligands) able to supply protons needed in the chemical reaction, and to use these metal-ligand complexes to enable conversion of CO2 to CO, the first step in activating the greenhouse gas in the formation of hydrocarbon chemicals. The research has broader societal impact both in developing access to solar energy in an efficient and storable way and in removing the CO2 from the environment, thus turning a harmful waste product into a useful resource. The project also has broader impact in meeting the CAREER-specific criterion of integrating research and educational activities, which involve both students and teachers in the local middle/high schools in energy-related projects and educational experiences. Dr. Marinescu is also developing mentoring programs for women at undergraduate, graduate, and postdoctoral levels to increase the participation of this underrepresented group in science fields. With funding from the Chemical Catalysis Program of the Chemistry Division, Professor Smarandra Marinescu of the Department of Chemistry at University of Southern California is synthesizing several macrocyclic aminopyridine complexes and evaluating their catalytic properties for the reduction of CO2. Preliminary studies indicate that cobalt complexes with pendant NH groups act as efficient electrocatalysts for the reduction of CO2 to CO with excellent Faradaic efficiencies. In comparison, the cobalt complexes with pendant tertiary amines are not as efficient CO2-reduction catalysts, suggesting that the presence of the pendant NH moiety of the secondary amine is crucial for catalysis. Stoichiometric studies are performed to detect and characterize proposed intermediates in the catalytic cycle. The prepared catalysts are studied structurally, electrochemically and spectroscopically to understand their chemical reactivity. These fundamental studies further the fundamental understanding of how hydrogen bonding facilitates the reduction of CO2 and aid in the development of practical catalysts using inexpensive metals. Additionally, there are several broader impacts directly tied to improving and diversifying the pipeline of young scientists interested and engaged in chemistry. The educational components are integrated with energy and catalysis applications, and target middle/high school students and teachers. Dr. Marinescu is also developing mentoring programs for women at undergraduate, graduate, and postdoctoral levels to increase the participation of this underrepresented group in STEM fields.