title: Observing the growth of metal-organic frameworks by in situ liquid cell transmission electron microscopy.
abstract: Liquid cell transmission electron microscopy (LCTEM) can provide direct observations of solution-phase nanoscale materials, and holds great promise as a tool for monitoring dynamic self-assembled nanomaterials. Control over particle behavior within the liquid cell, and under electron beam irradiation, is of paramount importance for this technique to contribute to our understanding of chemistry and materials science at the nanoscale. However, this type of control has not been demonstrated for complex, organic macromolecular materials, which form the basis for all biological systems and all of polymer science, and encompass important classes of advanced porous materials. Here we show that by controlling the liquid cell membrane surface chemistry and electron beam conditions, the dynamics and growth of metal-organic frameworks (MOFs) can be observed. Our results demonstrate that hybrid organic/inorganic beam-sensitive materials can be analyzed with LCTEM and, at least in the case of ZIF-8 dynamics, the results correlate with observations from bulk growth or other standard synthetic conditions. Furthermore, we show that LCTEM can be used to better understand how changes to synthetic conditions result in changes to particle size. We anticipate that direct, nanoscale imaging by LCTEM of MOF nucleation and growth mechanisms may provide insight into controlled MOF crystal morphology, domain composition, and processes influencing defect formation.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Patterson
authors.affiliation: ‡Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Patricia
authors.initials: P
authors.lastname: Abellan
authors.forename: Michael S
authors.initials: MS
authors.lastname: Denny
authors.affiliation: §Department of Industrial and Manufacturing Engineering, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Chiwoo
authors.initials: C
authors.lastname: Park
authors.affiliation: ‡Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Nigel D
authors.initials: ND
authors.lastname: Browning
authors.forename: Seth M
authors.initials: SM
authors.lastname: Cohen
authors.affiliation: ‡Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.|∥Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354, United States.
authors.forename: James E
authors.initials: JE
authors.lastname: Evans
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Gianneschi