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

CHE-1555387 CAREER：用于小分子活化的具有悬垂质子继电器的金属络合物; Smaranda C. Marinescu，南加州大学（USC）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，同时对环境的影响最小。 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，存储和分配中的几个重要问题，以便利用太阳辐射来满足全球能源需求。一种很有前途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的不期望的“温室气体”副产品，其是用于太阳能驱动的催化以生产烃燃料的潜在的丰富的经济原料。从自然光合生物系统中获得灵感，Smarandra Marinescu博士正在为这一过程开发分子催化剂。 催化剂结构专门设计有能够CO2活化的氢键框架。该项目的研究目标是设计和合成由能够提供化学反应所需质子的带负电荷或中性分子片段（称为配体）支撑的第一行过渡金属的催化剂络合物，并使用这些金属-配体络合物将CO2转化为CO，这是激活碳氢化合物形成中的温室气体的第一步。该研究在以有效和可储存的方式开发太阳能以及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。 该项目还具有更广泛的影响，以满足职业的具体标准，整合研究和教育活动，其中涉及学生和教师在当地初中/高中在能源相关的项目和教育经验。 Marinescu博士还为本科生，研究生和博士后水平的女性制定了指导计划，以增加这一代表性不足的群体在科学领域的参与。在化学部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络合物，并评估其还原CO2的催化性能。初步研究表明，具有侧基NH基团的钴配合物作为有效的电催化剂用于将CO2还原为CO，具有优异的法拉第效率。相比之下，具有侧链叔胺的钴络合物不是有效的CO2还原催化剂，这表明仲胺的侧链NH部分的存在对于催化是至关重要的。进行化学计量研究以检测和表征催化循环中的拟定中间体。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CO2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直接关系到改善和多样化的年轻科学家的管道感兴趣和从事化学。教育部分与能源和催化应用相结合，目标是初中/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开发辅导计划，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.