Heat capacity and thermodynamic functions of crystalline forms of the metal-organic framework zinc 2-methylimidazolate, Zn(MeIm)2

Peter F. Rosen; Jason J. Calvin; Matthew S. Dickson; Athanassios D. Katsenis; Tomislav Friščić; Alexandra Navrotsky; Nancy L. Ross; Alexander I. Kolesnikov; Brian F. Woodfield

doi:10.1016/j.jct.2019.05.008

Heat capacity and thermodynamic functions of crystalline forms of the metal-organic framework zinc 2-methylimidazolate, Zn(MeIm)₂

Peter F. Rosen, Jason J. Calvin, Matthew S. Dickson, Athanassios D. Katsenis, Tomislav Friščić, Alexandra Navrotsky, Nancy L. Ross, Alexander I. Kolesnikov, Brian F. Woodfield

Direct Geometry

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

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 C_p,m°, Δ₀^TS_m°, Δ₀^TH_m°, and Φ_m° 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.

Original language	English
Pages (from-to)	160-169
Number of pages	10
Journal	Journal of Chemical Thermodynamics
Volume	136
DOIs	https://doi.org/10.1016/j.jct.2019.05.008
State	Published - Sep 2019

Funding

The heat capacity work was financially supported by a grant from the U.S. Department of Energy under grant DE-SC0016446 . Data analysis based on recent measurements of enthalpies of transformation was supported by the U.S. Department of Energy under grant DE-SC0016573 . The INS work was financially supported by a grant from the U.S. Department of Energy under grant DE-SC0016448 . TF and ADK acknowledge the support of NSERC Strategic Grant (Grant no. NSERC STPGP 463405-14 ), the NSERC E.W.R. Steacie Memorial Fellowship (TF), and FRQNT Post-doctoral Bursary (ADK). The neutron-scattering research at the Spallation Neutron Source, Oak Ridge National Laboratory, was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The heat capacity work was financially supported by a grant from the U.S. Department of Energy under grant DE-SC0016446. Data analysis based on recent measurements of enthalpies of transformation was supported by the U.S. Department of Energy under grant DE-SC0016573. The INS work was financially supported by a grant from the U.S. Department of Energy under grant DE-SC0016448. TF and ADK acknowledge the support of NSERC Strategic Grant (Grant no. NSERC STPGP 463405-14), the NSERC E.W.R. Steacie Memorial Fellowship (TF), and FRQNT Post-doctoral Bursary (ADK). The neutron-scattering research at the Spallation Neutron Source, Oak Ridge National Laboratory, was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

Funders	Funder number
Office of Basic Energy Sciences
Scientific User Facilities Division
U.S. Department of Energy	DE-SC0016573, DE-SC0016448, DE-SC0016446
Oak Ridge National Laboratory
Natural Sciences and Engineering Research Council of Canada	NSERC STPGP 463405-14
Fonds de Recherche du Québec - Nature et Technologies

Keywords

Heat capacity
Inelastic neutron scattering
MOFs
ZIF-8
Zeolitic imidazolate frameworks

Access to Document

10.1016/j.jct.2019.05.008

Cite this

Rosen, P. F., Calvin, J. J., Dickson, M. S., Katsenis, A. D., Friščić, T., Navrotsky, A., Ross, N. L., Kolesnikov, A. I., & Woodfield, B. F. (2019). Heat capacity and thermodynamic functions of crystalline forms of the metal-organic framework zinc 2-methylimidazolate, Zn(MeIm)₂. Journal of Chemical Thermodynamics, 136, 160-169. https://doi.org/10.1016/j.jct.2019.05.008

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title = "Heat capacity and thermodynamic functions of crystalline forms of the metal-organic framework zinc 2-methylimidazolate, Zn(MeIm)2",

abstract = "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.",

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AU - Calvin, Jason J.

AU - Dickson, Matthew S.

AU - Katsenis, Athanassios D.

AU - Friščić, Tomislav

AU - Navrotsky, Alexandra

AU - Ross, Nancy L.

AU - Kolesnikov, Alexander I.

AU - Woodfield, Brian F.

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