Molecular Characterization of Water Oxidation in Metal-Organic Frameworks through Computer Simulations

计算机模拟在金属有机骨架中水氧化的分子表征计算机模拟已经成为获得对复杂分子过程的关键见解的有力工具，否则很难通过其他方法获得这些过程。然而，实现逼真和预测性模拟所需的精度是一项挑战。在这个项目中，帕萨尼博士和他的团队正在开发和应用一种新颖而强大的模拟方法来模拟一类被称为金属有机骨架(MOF)的高度多孔固体中的水氧化。水氧化是自然光合作用中的关键反应之一。因此，在分子水平上了解水氧化的步骤可能有助于人工光合作用系统的发展。MOF是一种相对较新的材料，是制作这些催化剂的理想材料。帕萨尼博士和他的团队开展的研究正在推进MOF及其化学的理论和计算机模拟，这是合理开发新催化剂的关键。在开展研究活动的同时，正在制定一项创新的教育和推广计划，向一年级和二年级的本科生介绍化学和材料研究中的计算方法。帕萨尼博士和他的团队还通过加州大学圣迪戈分校的暑期交流项目，促进贫困和代表不足的少数族裔学生对STEM学科的兴趣。对如何控制水氧化为分子氧的基本了解是开发人工系统以获取和转换太阳能以及实现可见光驱动的有机合成的先决条件。众所周知，水作为电子供体的可用性开启了各种各样的还原过程，这些过程可以由电力或阳光驱动。由于水是化石燃料燃烧的最终产物之一，H2O分子重新转化为燃料的过程涉及热力学上的上行反应，即去除氧原子。在这个项目中，Pesani博士和他的团队正在进行基础研究，以调查金属有机框架(MOF)中涉及水氧化反应的基本步骤。MOF是一类相对较新的具有较大比表面积的多孔材料，已在气体储存(如甲烷和氢气储存)、碳捕获、烃类分离、化学传感、非线性光学、生物医学成像、药物输送、催化、电性和质子传导性、磁性和发光方面得到了应用。由于MOF的结构和物理化学性质是高度可调的，MOF是构建高效太阳能收集和转换功能器件的很有前途的平台。帕萨尼博士和他的团队正在开发和应用新的模拟方法，将分子相互作用的多体表示与先进技术相结合来描述凝聚相中的化学反应，以表征与MOF中催化过程相关的基本步骤。这些信息是合理设计新的MOF结构的关键，新的MOF结构具有专门为太阳能收集和转换量身定做的特性。研究项目的跨学科性质为在不同学科之间进行培训提供了一个非同寻常的机会，在纳米尺度上提供了物理学基本定律和材料分子性质之间的桥梁和相互联系。在这种情况下，指导和推广活动是专门设计的，旨在通过加州大学圣迭戈分校暑期交换计划的开发和实施，在来自贫困和代表性不足的少数族裔的高中生和大学生中促进科学学科。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Molecular Characterization of Water Oxidation in Metal-Organic Frameworks through Computer SimulationsComputer simulations have become a powerful tool to gain critical insights into complex molecular processes, which are otherwise difficult to obtain by other means. However, achieving the necessary accuracy for realistic and predictive simulations is a challenge. In this project, Dr. Paesani and his group are developing and applying a novel and powerful simulation methodology to model water oxidation in a class of highly porous solids known as metal-organic frameworks (MOFs). Water oxidation is one of the key reactions in natural photosynthesis. Therefore, understanding the steps involved in water oxidation at the molecular level may aid in the development of artificial photosynthetic systems. MOFs are a relatively new class of materials and are ideal for these catalysts. The studies carried out by Dr. Paesani and his group are advancing both the theory and the computer modeling of MOFs and their chemistry, which are key to the rational development of new catalysts. In parallel with the research activities, an innovative education and outreach plan is being established to introduce freshman and sophomore undergraduate students to computational methods in chemistry and materials research. Dr. Paesani and his group are also promoting interest in STEM disciplines among underprivileged and underrepresented minority students through the development of summer exchange programs at the University of California - San Diego.The fundamental understanding of how to control water oxidation to molecular oxygen is a prerequisite for the development of artificial systems to harvest and convert solar energy as well as to enable visible-light-driven organic synthesis. It is well known that the availability of water as an electron donor opens up a wide variety of reductive processes that can be driven with electricity or sunlight. Since water is one of the ultimate products of fossil fuel combustion, the conversion of H2O molecules back into fuel involves thermodynamically uphill reactions that remove oxygen atoms. In this project, Dr. Paesani and his group are performing fundamental studies to investigate the elementary steps involved in water oxidation reactions in metal-organic frameworks (MOFs). MOFs are a relatively new class of porous materials with large surface areas that have already found application in gas storage (e.g., methane and hydrogen storage), carbon capture, hydrocarbon separation, chemical sensing, nonlinear optics, biomedical imaging, drug delivery, catalysis, electrical and proton conductivity, magnetism, and luminescence. Since MOF structure and physicochemical properties are highly tunable, MOFs represent promising platforms for building efficient functional devices for solar energy harvesting and conversion. Dr. Paesani and his group are developing and applying novel simulation methodologies that combine many-body representations of the molecular interactions with advanced techniques to describe chemical reactivity in the condensed phase to characterize the elementary steps associated with catalytic processes in MOFs. This information is key to the rational design of new MOF structures with properties specifically tailored for solar energy harvesting and conversion. The interdisciplinary nature of the research project represents an extraordinary opportunity for training at the interface of different disciplines, providing bridges and inter-connections between the fundamental laws of physics and the molecular properties of materials at the nanoscale. In this context, mentoring and outreach activities are specifically designed to promote science disciplines among high school and college students from underprivileged and underrepresented minorities through the development and implementation of summer exchange programs at UC San Diego.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.