August 1, 2014.
Metal organic frameworks (MOFs) are synthetic materials made of a cage-like lattice with consistently spaced pores. The size of these pores are the defining characteristic of a MOF, as it determines which gases are allowed to pass through and which can be trapped. Examples of their potential use can be greenhouse gas sequestration or storage. Currently, the synthesis of MOFs is based on trial-and-error, and the successes are not well understood. We are working on building the theoretical framework that describes how a particular MOF, MIL-101, comes together during synthesis. Our initial approach was to simulate the possible reactions with chemical kinetics through Cantera (a software suite that works through Python). To do this, a list of all possible intermediates with their thermodynamic properties is required. Another approach is to calculate the chemical force field potentials, and simulate how the atoms themselves behave during the synthesis process. For both purposes we minimized the energy of the structure of one known intermediate, called ML3 (a metal core with three linkers) through Assisted Model Building with Energy Refinement (AMBER) and with electronic structure calculations through Gaussian 09. In the end, the parameters that defined this minimized structure of ML3 were found. These can be used further to build the MIL-101 mechanism for use in Cantera, as well as the force field simulations.
Materials Chemistry | Physical Chemistry
Pacific Northwest National Laboratory (PNNL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).