Defects and Doping in Metal-Organic Frameworks

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NONTECHNICAL SUMMARYMetal-organic frameworks are a family of highly crystalline and porous materials, constructed from molecular building blocks. Most metal-organic frameworks have been assumed to be defect-free scaffolds that glean their properties from their highly ordered, repeating chemical structures. However, it is becoming increasingly clear that defects may play a more important role in determining the properties of these materials than so far assumed. This award supports research utilizing computational materials and chemistry techniques to examine the opportunities that emerge from defect sites in metal-organic frameworks. The PI will employ state-of-the-art computational methods to examine defects that give rise to increased electronic conductivity in the scaffolds, which could enable novel energy storage technologies, as well as defects that create sites to append and perform catalytic transformations. This award also supports strengthening the PI's existing outreach program centered around improving scientific literacy by teaching chemistry through the lens of coffee. In particular, the PI will (i) create an open-source library of peer-reviewed coffee-related scientific articles and write single-page summaries of the articles' key data and learning outcomes, and (ii) organize a seminar tour in African coffee-producing countries with the purpose of increasing awareness of the PI's work, recruiting students, and learning from these communities.TECHNICAL SUMMARYMetal-organic frameworks are an emergent class of porous, solid-state materials whose properties are widely thought to be determined by their bulk composition and topologies. Previous work has shown that electronic structure calculations on the crystallographic structures are instructive in predicting both photophysical properties and electronic properties in a wide variety of scaffolds. However, it is becoming increasingly clear that defects may play a more major role in determining the properties of these materials than so far assumed. This award supports computational research aimed at assessing the thermodynamic, electronic, and photophysical properties of a range of known defective scaffolds through the application of first principles defect calculations. The research activities include i) an exploration of the impact of vacancies and interstitials, and the emergent electronic properties associated with these defects; ii) examine hydrogenic interstitial-coupled electron transfer reactions that will enable both n- and p-type doping in the series of known conductive metal-organic frameworks; and iii) examination of hydrogenic/cationic defects in insulating metal-organic frameworks as a route to stabilizing exotic oxidation states through population of the conduction band. This award also supports strengthening the PI's existing outreach program centered around improving scientific literacy by teaching chemistry through the lens of coffee. In particular, the PI will (i) create an open-source library of peer-reviewed coffee-related scientific articles and write single-page summaries of the articles' key data and learning outcomes, and (ii) organize a seminar tour in African coffee-producing countries with the purpose of increasing awareness of the PI's work, recruiting students, and learning from these communities.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.