Modeling Catalysis for Sustainable Processes

明尼苏达大学化学系的Christopher J. Cramer教授将采用计算/理论模型来研究基于铜、铁、钴和钌的单核和多核过渡金属配合物，该项目由化学系化学结构、动态和机制B项目资助。重点是描述与它们催化与可持续性特别相关的反应的能力有关的机械细节。优先研究的催化过程包括(i)未活化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，第二个催化过程是将太阳能转化为绿色化学燃料（氢）的关键反应，第三个催化过程提供了将廉价而丰富的二氧化碳转化为工业上有用的商品化学品（如甲醛和甲醇）的机会，这不仅从经济角度来看，还因为大气中二氧化碳含量的增加对全球气候变化的影响。任何本地开发的实现新模型的代码/软件都将广泛地提供给更大的化学社区，并且将模型纳入开放源代码和商业代码将进一步扩展它们的可用性。外展和指导活动将通过与明尼苏达大学的一些项目继续合作来完成，包括科学与工程学院暑期桥梁项目、多元文化暑期研究机会项目、北极星STEM联盟/路易斯斯托克斯少数民族参与联盟项目等。密度泛函和高度相关的单和多决定波函数理论将应用于复杂的化学系统，旨在从可持续性的角度催化感兴趣的反应。为了处理周围凝聚相对催化循环的影响，将采用用于平衡和非平衡情况的连续统（和簇-连续统）溶剂化模型（例如，分别计算标准还原势和溶剂变色位移）。在可用的情况下，将根据实验数据确定和验证热化学和光谱数量。优先研究的目标包括水分解，特别是以地球上丰富的金属为基础的催化剂，例如，在一些以铜或铁为基础的系统中，其机理细节仍然不清楚。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，为了了解那些促进反应的电子结构细节（以及它们如何受到配体的影响），将研究单核和多核过渡金属配合物结合和激活二氧化碳还原的能力。最后，“绿色”氧化反应采用分子氧作为氧化剂和激活C-H键，例如，将探索系统的催化活性已经观察到基于铜或锰含配位化合物。

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.