Unusual Adsorption Site Behavior in PCN-14 Metal–Organic Framework Predicted from Monte Carlo Simulation

• Published in: Journal of the American Chemical Society Vol. 133; no. 48; pp. 19282 - 19285
• Main Authors: Lucena, Sebastião M. P, Mileo, Paulo G. M, Silvino, Pedro F. G, Cavalcante, Célio L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07-12-2011
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja207593c

The adsorption equilibrium of methane in PCN-14 was simulated by the Monte Carlo technique in the grand canonical ensemble. A new force field was proposed for the methane/PCN-14 system, and the temperature dependence of the molecular siting was investigated. A detailed study of the statistics of the center of mass and potential energy showed a surprising site behavior with no energy barriers between weak and strong sites, allowing open metal sites to guide methane molecules to other neighboring sites. Moreover, this study showed that a model assuming weakly adsorbing open metal clusters in PCN-14, densely populated only at low temperatures (below 150 K), can explain published experimental data. These results also explain previously observed discrepancies between neutron diffraction experiments and Monte Carlo simulations.