Supramolecular interactions induced hinge-like motion of a metal–organic framework accompanied by anisotropic thermal expansion

Ionothermal reaction between MnII(acetate)2·4H2O and 1,3,5-benzenetricarboxylic acid (H3BTC) in either of the two ionic liquids 1-ethyl-3-methylimidazolium bromide (EMIMBr) and 1-ethyl-3-methylimidazolium tosylate (EMIMOTs) resulted in the formation of the new metal–organic framework (MOF) EMIM[MnIIBTC] (BTC = 1,3,5-benzenetricarboxylate). The compound crystallizes in the orthorhombic space groupPbcawith unit-cell parameters ofa= 14.66658 (12),b= 12.39497 (9),c= 16.63509 (14) Å at 100 K. Multi-temperature single-crystal (15–340 K) and powder X-ray diffraction studies (100–400 K) reveal strongly anisotropic thermal expansion properties. The linear thermal expansion coefficients, αL(l), attain maximum values at 400 K along thea- andb-axis, with αL(a) = 115 × 10−6 K−1and αL(b) = 75 × 10−6 K−1. At 400 K a negative thermal expansion coefficient of −40 × 10−6 K−1is observed along thec-axis. The thermal expansion is coupled to a continuous deformation of the framework, which causes the structure to expand in two directions. Due to the rigidity of the linker, the expansion in theabplane causes the network to contract along thec-axis. Hirshfeld surface analysis has been used to describe the interaction between the framework structure and the EMIM cation that resides within the channel. This reveals a number of rather weak interactions and one governing hydrogen-bonding interactions.

Download Full-text

Elucidating the mechanism responsible for anisotropic thermal expansion in a metal-organic framework

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273315093158 ◽

2015 ◽

Vol 71 (a1) ◽

pp. s464-s464

Author(s):

Dewald P. van Heerden ◽

Catharine Esterhuysen ◽

Leonard J. Barbour

Keyword(s):

Thermal Expansion ◽

Metal Organic Framework ◽

Anisotropic Thermal Expansion ◽

Metal Organic ◽

Organic Framework

Download Full-text

Large anisotropic negative thermal expansion in Cu-TDPAT metal-organic framework: A combined in situ X-ray diffraction and DRIFTS study

Nano Research ◽

10.1007/s12274-020-2792-y ◽

2020 ◽

Vol 14 (2) ◽

pp. 404-410 ◽

Cited By ~ 2

Author(s):

Mehrdad Asgari ◽

Ilia Kochetygov ◽

Hassan Abedini ◽

Wendy L. Queen

Keyword(s):

Thermal Expansion ◽

Metal Organic Framework ◽

Negative Thermal Expansion ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Organic Framework

Download Full-text

Proposal for a material with negative thermal expansion

International Journal of Modern Physics B ◽

10.1142/s0217979216502386 ◽

2016 ◽

Vol 30 (32) ◽

pp. 1650238

Author(s):

Mikrajuddin Abdullah

Keyword(s):

Thermal Expansion ◽

Glass Transition ◽

Transition Temperature ◽

Metal Organic Framework ◽

Negative Thermal Expansion ◽

Lennard Jones ◽

Model Predictions ◽

Metal Organic ◽

Organic Framework

I propose a model of a material that exhibits negative thermal expansion (NTE) properties and criteria for the occurrence of linear and volumetric NTE. I derived the criteria for an arbitrary force between rigid units in the material. These criteria are also discussed specifically for the Lennard–Jones (6–12) potential and in more detail for metal–organic framework (MOF) materials comprising rigid units connected by organic linkers. Qualitatively, the model predictions can explain some observed results. Surprisingly, the model can produce equations for the transition temperature from NTE to positive thermal expansion (PTE), [Formula: see text] K, which is exactly the same as the temperature at which the glass transition begins to occur in most polymers, i.e., [Formula: see text] K.

Download Full-text