Heat capacity and thermodynamic functions of crystalline forms of the metal-organic framework zinc 2-methylimidazolate, Zn(MeIm)2
| Autor: | Nancy L. Ross, Alexander I. Kolesnikov, Matthew S. Dickson, Jason J. Calvin, Tomislav Friščić, Alexandra Navrotsky, Brian F. Woodfield, Athanassios D. Katsenis, Peter F. Rosen |
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| Rok vydání: | 2019 |
| Předmět: |
Chemistry
chemistry.chemical_element 02 engineering and technology Zinc 010402 general chemistry 01 natural sciences Heat capacity Atomic and Molecular Physics and Optics Inelastic neutron scattering 0104 chemical sciences Gibbs free energy Metal symbols.namesake chemistry.chemical_compound 020401 chemical engineering visual_art symbols Sodalite visual_art.visual_art_medium Physical chemistry General Materials Science Metal-organic framework 0204 chemical engineering Physical and Theoretical Chemistry Zeolitic imidazolate framework |
| Zdroj: | The Journal of Chemical Thermodynamics. 136:160-169 |
| ISSN: | 0021-9614 |
| DOI: | 10.1016/j.jct.2019.05.008 |
| Popis: | Zeolitic imidazolate frameworks (ZIFs) are composed of metal atoms connected with imidazole-like linkers, and these frameworks have potential for applications in molecular sieving, gas sequestration, and catalysis. In addition, these materials form true polymorphs with the same chemical composition but different topologies. In this paper, we present the results of low temperature heat capacity and inelastic neutron scattering studies of the sodalite (SOD) and diamondoid (dia) topologies of the popular zinc 2-methylimidazolate framework, Zn(MeIm)2. Molar heat capacities from 1.8 K to 300 K are presented, along with theoretical fits and the values of Cp,m°, Δ0TSm°, Δ0THm°, and Φm° calculated from those fits. The Gibbs energy of the transformation from SOD to dia is −(4.6 ± 2.2) kJ, and this transformation is primarily enthalpically driven. The results of this study are compared with previous measurements on the zinc 2-ethylimidazolate framework, Zn(EtIm)2. Inelastic neutron scattering measurements confirm the presence of low energy modes and suggest that the higher heat capacity of SOD at low temperatures is due to the dynamics of the methyl groups on the methylimidazolate linkers. |
| Databáze: | OpenAIRE |
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