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Experimental Evidence for a General Model of Modulated MOF Nanoparticle Growth

preprint
submitted on 31.05.2020 and posted on 02.06.2020 by Checkers R. Marshall, Sara Staudhammer, Carl Brozek

Nanoparticles of metal-organic frameworks (nanoMOFs) boast superior properties compared to their bulk analogs, yet little is known about how common synthetic parameters dictate particle sizes. Here, we provide experimental evidence for the “seesaw” model of nanoMOF growth. Solution acidity, ligand excess, and reactant concentrations are decoupled and shown to form the key independent determinants of nanoMOF sizes, thereby validating the proposal that nanoMOFs arise from coupled equilibria involving ligand deprotonation and metal-ligand complexation. By achieving the first demonstration of a seesaw relationship between nanoMOF sizes and ligand excess, these results provide further proof of the model, as they required deliberate manipulation of relationships outlined by the model. Exploring the relative impacts of these parameters reveals that ligand excess has the greatest ability to decrease sizes, although low acidity and high concentrations can exhibit similar effects. As a complement to existing models of polymer formation and crystal growth, the seesaw model therefore offers a powerful tool for reliable control over nanoMOF sizes.

History

Email Address of Submitting Author

cbrozek@uoregon.edu

Institution

University of Oregon

Country

United States

ORCID For Submitting Author

0000-0002-8014-7904

Declaration of Conflict of Interest

The authors declare no conflict of interest.

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