Modeling Catalysis for Sustainable Processes

在这项由化学系化学结构、动态和机理B计划资助的项目中，明尼苏达大学化学系的Christopher J.Cramer教授将使用计算/理论模型来研究基于铜、铁、钴和Ru的单核和多核过渡金属络合物，重点是表征与它们催化反应的能力相关的机理细节，这些反应对可持续性具有特殊的相关性。将被指定为最优先研究的催化过程包括(I)未被激活的C-H键的氧化，(Ii)水氧化生成分子氢和氧，(Iii)二氧化碳的还原。第一个催化过程提供了从更便宜的碳氢化合物原料中获得高价值功能化分子的途径，第二个是在将太阳能转化为绿色化学燃料(氢)的过程中至关重要的反应，第三个过程提供了将廉价而丰富的二氧化碳转化为甲醛和甲醇等工业有用的商品化学品的机会，这不仅从经济角度来看具有相当大的兴趣，还因为大气中二氧化碳水平的上升对全球气候变化的影响。任何实现新模型的本地开发的代码/软件都将广泛提供给更大的化学界，正在进行的将模型纳入开源和商业代码将进一步扩大它们的可用性。外展和指导活动将通过与明尼苏达大学的许多项目的持续合作来完成，包括科学与工程学院夏季桥梁计划、多元文化夏季研究机会计划以及北极星STEM联盟/Louis Stokes少数群体参与联盟计划等。密度泛函和高度相关的单决定波函数理论将应用于从可持续发展的角度催化感兴趣的反应的复杂化学系统。为了处理周围凝聚相对催化循环的影响，将采用平衡和非平衡情况下的连续(和团簇-连续)溶剂化模型(例如，分别计算标准还原电势和溶剂变色位移)。热化学和光谱量将被确定，并与可用的实验数据进行验证。优先研究的目标包括水的分解，特别是基于富含地球的金属的催化剂，例如，在几个基于铜或铁的系统中，对这些催化剂的机械细节仍然不清楚。二氧化碳的还原仍然是另一个具有挑战性的问题，特别是从催化的角度来看，将审查单核和多核过渡金属配合物结合和激活二氧化碳进行还原的能力，以了解促进反应的电子结构细节(以及它们如何受到配体的影响)。最后，将探索以分子氧为氧化剂并激活C-H键的“绿色”氧化反应，例如，对于已观察到催化活性的基于铜或锰的配位化合物的体系。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Christopher J. Cramer of the Department of Chemistry at the University of Minnesota will employ computational/theoretical models to study mono- and polynuclear transition-metal complexes based on copper, iron, cobalt, and ruthenium, with the key focus being to characterize mechanistic details associated with their ability to catalyze reactions having special relevance to sustainability. Catalytic processes that will be assigned the highest priority for study include (i) the oxidation of otherwise unactivated C-H bonds, (ii) water oxidation to generate molecular hydrogen and oxygen, (iii) reduction of carbon dioxide. The first catalytic process provides access to high-value functionalized molecules from cheaper hydrocarbon feedstocks, the second is a reaction of key importance in the conversion of solar energy into a green chemical fuel (hydrogen), and the third offers the opportunity to convert cheap and abundant CO2 into industrially useful commodity chemicals like formaldehyde and methanol, which is of considerable interest not only from an economic perspective, but also because of the influence of increasing atmospheric CO2 levels on global climate change. Any locally developed code/software that implements new models will be made broadly available to the greater chemistry community, and ongoing incorporation of models into open source and commercial codes will further extend their availability. Outreach and mentoring activities will be accomplished through continued work with a number of University of Minnesota programs, including the College of Science & Engineering Summer Bridge Program, the Multicultural Summer Research Opportunities Program, and the North Star STEM alliance/Louis Stokes Alliances for Minority Participation program, amongst others.Density functional and highly correlated single and multideterminantal wave function theories will be applied to complex chemical systems designed to catalyze reactions of interest from a sustainability standpoint. In order to treat the influence of a surrounding condensed phase on the catalytic cycle, continuum (and cluster-continuum) solvation models for use in both equilibrium and non-equilibrium situations (e.g., computations of standard reduction potentials and solvatochromic shifts, respectively) will be employed. Thermochemical and spectral quantities will be determined and validated against experimental data where available. High priority targets for study include water splitting focusing especially on catalysts based on earth-abundant metals, for which mechanistic details remain obscure in several systems based on copper or iron, for example. Reduction of carbon dioxide remains another challenging problem, particularly from a catalytic standpoint, and the ability of mono- and polynuclear transition-metal complexes to bind and activate CO2 to reduction will be examined in order to understand those electronic structure details (and how they are influenced by ligands) that facilitate reaction. Lastly, "green" oxidation reactions employing molecular oxygen as the oxidant and activating C-H bonds, for example, will be explored for systems where catalytic activity has been observed based on copper or manganese containing coordination compounds.