Expanding the MOF Toolkit to Access New Solid-State Functionality: Porous Materials based on Phosphines, Arsines and Chalcogenides

本研究项目由美国国家科学基金会固态和材料化学项目支持，涉及新型多孔材料的制备和研究，其独特的性能为我们未来的能源需求提供了根本性的进步。多孔材料在许多大规模工业应用中是至关重要的，从水净化到空气成分的分离，从捕获有毒化学物质到燃料的生产。然而，为了使现有的工艺更加高效和环保，必须改善执行这些功能的材料的性能。德克萨斯大学奥斯汀分校的汉弗莱小组正致力于设计和合成新的多孔材料，这种材料可以在其孔隙中加入广泛的明确定义的金属物种。目前，化学活性金属不能容易地或系统地结合到大多数多孔材料中。为这个问题提供一个通用的解决方案会导致材料能够以更大的选择性和更高的容量捕获某些有价值的化学物质。由PI，研究生和本科生研究人员组成的研究团队共同准备模型材料，使用最先进的表征工具对其进行研究，以获得有关其性质的基本信息。在整个过程中，研究团队与理论化学家和光束线设施的科学家合作，以更深入地了解结构如何影响功能。该项目整合了一个创新的本科教育项目，称为奥斯汀国际框架（AIF）。AIF为德州大学奥斯汀分校的本科生科学家提供完全沉浸式的奖学金支持的国际交流体验；学生将有机会在国际知名的海外大学学习和研究多孔材料的发展，从而开阔视野，亲身体验科学的全球性。该项目由美国国家科学基金会固态与材料化学项目支持，其科学目标是基于未开发的配体类别制备新的金属有机框架（MOF）材料，并深入了解其固态性质。随着这类新型多孔材料的潜在应用不断被发现，MOF研究领域继续以越来越快的速度扩展。MOF化学复杂性的潜在边界仍然未知。然而，这方面的进展是缓慢的，受到依赖于使用化学相似的有机成分发现MOF的限制。汉弗莱小组通过展示膦、砷和硫系配体可以赋予真正新的固态功能，极大地扩展了MOF的“工具箱”。由此产生的MOF微孔被结构明确的路易斯碱基修饰，可以作为具有高级固态功能（即小分子化学吸附，化学键激活）的低价低配位金属的合成后附着点。从本质上讲，目标mof是结晶的、原子精确的固体配体。这是一个具有挑战性的项目，但最终的材料提供了新的途径，系统地将广泛的工业相关金属物种纳入独特的密闭微孔环境中。从基本的角度来看，这些材料推进了mof化学反应性的前沿，并提供了理想的模型，在此模型上进行有关更强气体吸附过程的详细表征研究。从技术角度来看，能够选择性吸附和活化气体的新材料对于未来在大气修复和可再生燃料生产中的应用非常重要。除了为德州大学奥斯汀分校的本科生和研究生提供研究机会外，该项目还整合了一个创新的本科教育计划，称为奥斯汀国际框架（AIF）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical SummaryThis research program, which is supported by the Solid State and Materials Chemistry program at NSF, involves the preparation and studies of new porous materials, whose unique properties provide fundamental advances for our future energy needs. Porous materials are critical in many large-scale industrial applications, ranging from water purification to the separation of the components of air, and from the capture of toxic chemicals to the production of fuels. However, to make existing processes more efficient and environmentally-friendly, it is essential to improve the properties of materials that perform these functions. The Humphrey group at the University of Texas Austin is working to design and synthesize new porous materials that can incorporate a wide range of well-defined metal species inside their pores. At present, chemically reactive metals cannot be easily or systematically incorporated into most porous materials. Providing a general solution to this problem leads to materials that can capture certain valuable chemical species with greater selectivity and higher capacity. The research team comprised of the PI, graduate students and undergraduate researchers works together to prepare model materials, which are studied using state-of-the-art characterization tools to obtain fundamental information about their properties. Throughout this process, the research team collaborates with theoretical chemists and scientists at beamline facilities to gain a deeper understanding of how structure can affect function. This project integrates an innovative undergraduate educational program, called the Austin-International Framework (AIF). The AIF provides a fully immersive, scholarship-supported international exchange experience to UT Austin undergraduate scientists; students are given the opportunity to broaden their horizons by witnessing first-hand the global nature of science via a semester of study and research in porous materials development at one of several overseas universities of international acclaim. Technical SummaryThe scientific objective of this project, which is supported by the Solid State and Materials Chemistry program at NSF, is to prepare new metal-organic framework (MOF) materials based on unexplored classes of ligands, and to gain an in-depth understanding of their solid-state properties. The field of MOF research continues to expand at an increasing rate, as new potential applications of this novel class of porous materials are discovered. The potential boundaries of MOF chemical complexity remain unknown. However, advances in this regard are slow, restricted by the reliance of MOF discovery using chemically similar organic components. The Humphrey group significantly expands the MOF 'toolkit' by showing that phosphine, arsine and chalcogenide ligands can impart genuinely new solid-state functionalities. The resulting MOF micropores are decorated with structurally well-defined Lewis bases, which can be exploited as post-synthetic attachment points for low-valent, low-coordinate metal species that impart advanced solid-state functionalities (i.e., small molecule chemisorption, chemical bond activation). In essence, the target MOFs are crystalline, atomically-precise solid-state ligands. This is a challenging project, but the resulting materials provide new avenues to systematically incorporate a broad range of metal species of industrial relevance into uniquely confined micro-pore environments. From a fundamental perspective, these materials advance the frontiers of chemical reactivity in MOFs and provide ideal models on which to perform detailed characterization studies pertaining to stronger gas adsorption processes. From a technological perspective, new materials that enable selective adsorption and activation of gases are important for future applications in atmospheric remediation and the production of renewable fuels. In addition to providing research opportunities for undergraduate and graduate students at UT Austin, this project also integrates an innovative undergraduate educational program, called the Austin-International Framework (AIF).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.