CAREER: Tunable Metal Oxide Materials via Coordination Assembly of Molecular Clusters

非技术总结：固态金属氧化物是一类对当前和新兴技术至关重要的材料。然而，由于缺乏对单个原子位置的精确控制，使这些材料具有针对性和可预测的特性仍然是一个挑战。在这个由材料研究部固态和材料化学项目支持的项目中，Schimpf教授使用预先形成的分子构建块的组装作为金属氧化物的途径，具有明确的，广泛可调的成分和精确定制的性质。本研究包括合成材料、测量性能和设计假设的迭代循环，以了解在这些分子组装的金属氧化物中观察到的结构-性能关系。这些研究使人们对以下因素有了新的认识：(1)决定了从预制构件合成具有多种或复杂成分的金属氧化物的能力；(2)决定了所得到的固态材料的性质。该项目还为社区大学生提供了一个平台，让他们获得设计和研究能源相关材料的研究经验。加州大学圣地亚哥分校的研究人员与圣地亚哥地区西班牙裔社区学院的教师合作，为这些机构的学生设计项目并提供指导。这些努力的目标是吸引学生从事科学、技术、工程和数学（STEM）领域的职业，并为他们在这条职业道路上的未来步骤做好准备。技术摘要：该项目由材料研究部固态和材料化学项目支持，利用分子金属氧化物簇的配位组装来促进获得具有不同成分和定制性能的新型可广泛调谐的金属氧化物材料。与统计上掺杂的半导体不同，分子基材料提供了具有精确已知原子位置的复杂金属氧化物组成，从而能够进行仔细的结构-性能评估。研究人员采用迭代过程来设计和理解由金属阳离子桥接的多金属酸氧盐（POM）阴离子组成的簇基金属氧化物框架的模块化特性。这一过程允许评估哪些金属和簇特征在决定金属氧化物框架的组装和最终性能方面是重要的。研究的因素包括金属电荷、氧化态、硬/软酸度和簇电荷、尺寸和稳定性。通过合作，理论建模支持对观察到的结构-性能趋势的解释和对合理材料设计原则的最终预测。本研究结果有望为合理设计具有目标性能的分子基金属氧化物提供指导。这个项目也为社区大学生提供研究经验奠定了基础。圣地亚哥地区的社区学院为大部分来自弱势种族、民族或经济群体的学生提供服务，因此提供了一个机会，让我们人口中未被充分代表的部分参与科学、技术、工程和数学（STEM）的研究和培训。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 summary: Solid-state metal oxides are a class of materials vital to current and emerging technologies. Making these materials with targeted and predictable properties, however, remains a challenge due to the lack of precise control over individual atom location. In this project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, Prof. Schimpf uses the assembly of pre-formed molecular building-blocks as a route to metal oxides with well-defined, broadly tunable compositions and precisely tailored properties. This research consists of an iterative cycle of synthesizing materials, measuring properties and designing hypotheses to understand the structure-property relationships observed in these molecular-assembled metal oxides. The studies lead to new understanding of the factors that (1) govern the ability to synthesize metal oxides with diverse or complex compositions from pre-formed building-blocks and (2) dictate the properties of the resulting solid-state materials. This project also provides a platform for community college students to gain research experience designing and studying energy-relevant materials. The UC San Diego-based researchers work with faculty at Hispanic serving community colleges in the San Diego area to design projects for and mentor students at these institutions. The goals of these efforts are to attract students to careers in science, technology, engineering and mathematics (STEM) and to prepare them for future steps along this career path. Technical summary: This project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, uses the coordination assembly of molecular metal oxide clusters to facilitate access to new and widely tunable metal oxide materials with diverse compositions and tailored properties. Unlike statistically doped semiconductors, molecule-based materials offer access to complex metal oxide compositions with precisely known atom positions, enabling careful structure-property evaluations. The researchers employ an iterative process to design and understand the modular properties of cluster-based metal oxide frameworks consisting of polyoxometalate (POM) anions bridged with metal cations. This process allows evaluation of which metal and cluster characteristics are important in dictating the assembly and resulting properties of metal oxide frameworks. Factors that are investigated include metal charge, oxidation state and hard/soft acidity and cluster charge, size and stability. Through a collaboration, theoretical modeling supports explanations of observed structure-property trends and resulting predictions for rational materials design principles. Results from this research are anticipated to provide guidelines for the rational design of molecule-based metal oxides with targeted properties. This project also forms the foundation to provide research experiences for community college students. Community colleges in the San Diego area serve a large percentage of students from disadvantaged racial, ethnic or economic groups, and thus offer an opportunity to engage an underrepresented part of our population in science, technology, engineering and mathematics (STEM) research and training.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.