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

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.