CAS: Biologically Inspired Aminopyridine Complexes for CO2 Reduction

在化学系化学催化项目的支持下，Smaranda C。南加州大学的Marinescu将研究开发生物启发的催化系统，用于将有害的二氧化碳转化为化学燃料。开发清洁能源技术作为化石燃料的替代品，是面对全球迅速变暖的一项迫切需要。太阳能作为一种清洁能源受到了广泛关注，但重点主要集中在发电上。这种狭隘的关注并不能充分满足运输、供暖和工业用途对可再生燃料的需求，这些燃料占能源需求的70%左右。可持续能源的未来将需要一种非化石燃料的方法来形成化学原料，而利用太阳能发电对二氧化碳（CO2）和水（H2O）等丰富的小分子进行电化学还原是一种可行的途径。这种方法将允许以化学键的方式存储太阳能，就像自然界通过光合作用实现的那样，其中光子的能量用于驱动CO2还原为各种高能产品。受生物系统的启发，Marinescu小组将开发涉及氢键网络的分子催化剂，这些氢键网络能够通过多个质子和电子转移激活小分子。该项目将专注于开发一系列具有侧基胺的生物启发金属络合物，这将有助于了解质子中继对多电子，多质子反应的影响。配体框架允许电子和定位效应的良好控制，这将有利于结构活性研究。该研究计划包括一项教育计划，重点是为少数民族学生比例较高的当地社区学院的学生和教师提供研究机会，并为博士后妇女提供指导计划，以增加这一代表性不足的群体在科学领域的参与。这些推广和指导活动将长期影响大量个人：教师和几代学生，沿着南加州大学的研究人员。重要的是，参与这些努力的学生将培养一种为他们的科学和非科学社区做出贡献的文化，这种文化预计将持续到他们的成长期之后。南加州大学的Marinescu将研究悬垂质子中继对钴氨基吡啶大环化合物还原二氧化碳的影响。Marinescu小组最近的工作表明，一系列具有0至4个侧链仲胺（NH）的钴络合物显示出CO2还原速率与侧链NH部分的数量之间的线性相关性。实验和理论表明，侧挂的NH基团不直接将质子转移到CO2，而是从溶液中结合酸分子，导致形成催化剂-酸加合物，通过氢键网络保持在一起，这使得能够将质子从酸直接转移到活化的CO2底物。研究的目标是了解这些配合物的催化性能的因素，在活性和CO2还原的选择性方面，通过表征和改变这些金属氨基吡啶大环的电子环境（初级和次级配位球）。本项目的重点是合成和表征各种氨基吡啶配合物与侧氢键供体或阳离子基团，以了解这些部分对催化剂的活性和选择性的影响。科学教育目标将侧重于：（1）为喜瑞都学院的学生组织一次暑期讲习班，这是一所公立社区学院，来自代表性不足群体的学生比例很高，并在夏季接待一名喜瑞都学院的学生在Marinescu实验室进行为期8周的本科生研究;以及（2）该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

With the support of the Chemical Catalysis program in the Division of Chemistry, Smaranda C. Marinescu of the University of Southern California will study the development of biologically inspired catalytic systems for the conversion of harmful carbon dioxide into chemical fuels. The development of clean energy technologies as an alternative to fossil fuels is a critical need in the face of rapid planetary warming. Solar energy has received much attention as a clean energy source, but the focus has largely been on electricity generation. This narrow focus does not adequately meet the need for renewable fuels for transportation, heating, and industrial uses, which make up ~70% of energy needs. A sustainable energy future will require a non-fossil fuel method for the formation of chemical feedstocks, and the electrochemical reduction of abundant small molecules such as carbon dioxide (CO2) and water (H2O), using the solar-derived electricity is a viable pathway to do so. This approach will allow for storing of solar energy in chemical bonds in a similar way as nature accomplishes through photosynthesis, where the energy of photons is used to drive the reduction of CO2 to a variety of high-energy products. Inspired by biological systems, the Marinescu group will develop molecular catalysts that involve hydrogen-bonding networks which are capable of small molecule activation through multiple proton and electron transfers. This project will focus on the development of a series of biologically inspired metal complexes with pendant amines, which will allow for understanding the effect of proton relays on multi-electron, multi-proton reactions. The ligand framework allows for excellent control of electronic and positioning effects, which will facilitate structure-activity studies. Integrated into this research plan is an educational program focused on providing research opportunities to both students and teachers from local community colleges with a high percentage of minority students, and a mentoring program for women at the postdoctoral level to increase the participation of this underrepresented group in science. These outreach and mentoring activities will impact a significant number of individuals over the long term: teachers and generations of their students, along with researchers from USC. Importantly, students involved in these efforts will develop a culture of contributing to their scientific and non-scientific communities that is expected to last beyond their formative years.With the support of the Chemical Catalysis program in the Division of Chemistry, Smaranda C. Marinescu of the University of Southern California will study the effect of pendant proton relays on the CO2 reduction with cobalt aminopyridine macrocycles. Recent work in the Marinescu group has demonstrated that a series of cobalt complexes with zero to four pendant secondary amines (NH) displays a linear correlation between the rate of CO2 reduction and the number of pendant NH moieties. Experiment and theory suggest that the pendant NH groups do not directly transfer protons to CO2, but instead bind acid molecules from solution, leading to the formation of a catalyst-acid adduct, held together through a hydrogen-bonding network, that enables direct proton transfer from acid to the activated CO2 substrate. The research goal is to understand the factors that govern the catalytic properties of these complexes, in terms of activity and selectivity for CO2 reduction, by characterizing and altering the electronic environment (the primary and secondary coordination spheres) of these metal aminopyridine macrocycles. This project focuses on the synthesis and characterization of a variety of aminopyridine complexes with pendant hydrogen bond donors or cationic groups to understand the effects of these moieties on the catalyst activity and selectivity. The science education goals will focus on: (1) organizing a summer workshop for students from Cerritos College, a public community college with a high percentage of students from underrepresented groups and hosting a Cerritos College student in the Marinescu laboratory to perform undergraduate research for an 8-week period during the summer; and (2) developing a mentoring program for women at the postdoctoral level to increase the participation of women in science.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.