Abstract
The assembly mechanism of Metal-Organic Frameworks (MOFs) is controlled by the choice of solvent and the presence of spectator ions. In this paper, we apply enhanced sampling molecular dynamics methods to investigate the role of solvent and ions in the early stages of the synthesis of MIL-101(Cr). Microsecond-long well-tempered metadynamics simulations uncover a rich structural free energy landscape, with secondary building units (SBUs) adopting distinct crystal and noncrystal like configurations. In the presence of ions (Na+, F-), we observe a complex effect on the crystallinity of SBUs. By modulating the interactions between terephthalate linkers and Cr atoms, ions affect the abundance of crystal-like SBUs, consequently controlling the percentage of defects. Solvent effects are assessed by comparing water with N,N-dimethylformamide, in which SBU adducts are appreciably more stable and compact. These results shed light on how solvent and ionic strength impact the free energy of the assembly phenomena that ultimately control material synthesis.
| Original language | English |
|---|---|
| Pages (from-to) | 6073-6081 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 141 |
| Issue number | 14 |
| DOIs | |
| State | Published - Apr 10 2019 |
| Externally published | Yes |
Funding
Pacific Northwest National Laboratory (PNNL) is operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RL01830. The authors acknowledge the use of the UCL Legion High Performance Computing Facility (Legion @ UCL), and associated support services, in the completion of this work. L.K. was supported in part by the Pacific Northwest National Laboratory’s (PNNL) Laboratory Directed Research Development (LDRD) project. D.C.C. is grateful for the support from Research and Innovation at the University of Nevada, Reno. V.-A.G. acknowledges partial support by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-SUPPLEMENTARY MATERIAL AC02-05CH11231.