Adsorption-Induced Structural Transition of an Interpenetrated Porous Coordination Polymer: Detailed Exploration of Free Energy Profiles
| Autor: | Minoru T. Miyahara, Satoshi Watanabe, Hayato Sugiyama, Hideki Tanaka |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
chemistry.chemical_classification
Chemistry Coordination polymer Nanotechnology Surfaces and Interfaces Polymer Condensed Matter Physics Hysteresis chemistry.chemical_compound Adsorption Chemical physics Phase (matter) Metastability Electrochemistry Molecule General Materials Science Porous medium Spectroscopy |
| Zdroj: | Langmuir. 28:5093-5100 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la205063f |
| Popis: | Specific types of coordination polymers show an adsorption-induced structural transition, or so-called "gate adsorption", in which a host framework is said to change its structure from a "closed" nonporous phase to an "open" porous one for guest molecules. To identify the pathway for such a structural transition, we perform grand canonical Monte Carlo simulations for the adsorption of guest molecules in a host interpenetrated framework and calculate the free energy profiles of the structural changes in a complete three-dimensional space. In addition to the open phase found in our previous analyses along a fixed one-dimensional path, we reveal the existence of another open configuration. Each of the two open phases yields the status of global minimum to the other depending on the external pressure, resulting in a two-step isotherm. Moreover, the shape of adsorption hysteresis associated with the structural transition can change depending on the energy barrier between a metastable and a stable state that the system can overcome. Our simulations not only give a comprehensive understanding of stepped isotherms observed empirically but also suggest that isotherms with hysteretic gate adsorption is closely related to the thermal fluctuation of the system. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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