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

职业：金属配合物与挂式质子继电器小分子活化；南加州大学的斯玛兰达·c·马里内斯库：直接从阳光中获取的能源是一种极具吸引力的能源，既能满足全球对能源的需求，又能将对环境的影响降到最低。为了利用这种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。一种很有前景的方法是利用太阳能来驱动化学反应，从而产生易于储存的燃料。二氧化碳（CO2）是燃烧化石燃料和其他工业过程产生的不受欢迎的“温室气体”副产品，它可能是太阳能催化生产碳氢化合物燃料的一种丰富而经济的原料。受自然光合生物系统的启发，Smarandra Marinescu博士正在为这一过程开发分子催化剂。催化剂的结构是专门设计的氢键框架能够CO2活化。该项目的研究目标是设计和合成第一排过渡金属的催化剂配合物，这些过渡金属由带负电或中性的分子片段（称为配体）支撑，能够提供化学反应所需的质子，并利用这些金属-配体配合物将CO2转化为CO，这是激活碳氢化合物形成过程中温室气体的第一步。这项研究在以有效和可储存的方式开发太阳能和从环境中去除二氧化碳方面具有更广泛的社会影响，从而将有害的废物转化为有用的资源。该项目在满足将研究和教育活动结合起来的职业特定标准方面也具有更广泛的影响，这些活动涉及当地初中/高中的学生和教师参与与能源有关的项目和教育经验。Marinescu博士还在为本科、研究生和博士后级别的女性制定指导计划，以提高这一代表性不足的群体在科学领域的参与度。在化学催化项目的资助下，南加州大学化学系的Smarandra Marinescu教授正在合成几种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，具有悬垂NH基团的钴配合物具有良好的法拉第效率，是将CO2还原为CO的高效电催化剂。相比之下，钴配合物与叔胺的悬垂不是有效的二氧化碳还原催化剂，这表明仲胺的悬垂NH部分的存在对催化作用至关重要。进行化学计量学研究以检测和表征催化循环中提出的中间体。对制备的催化剂进行了结构、电化学和光谱研究，以了解其化学反应性。这些基础研究进一步加深了对氢键如何促进二氧化碳还原的基本理解，并有助于开发使用廉价金属的实用催化剂。此外，还有几个更广泛的影响与改善和多样化对化学感兴趣和从事化学的年轻科学家的管道直接相关。教育组件与能源和催化应用相结合，面向初高中学生和教师。Marinescu博士还在为本科、研究生和博士后级别的女性制定指导计划，以提高这一代表性不足的群体在STEM领域的参与度。

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.