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Influence of thermal and mechanical stimuli on the behavior of Al-CAU-13 metal–organic framework

DOI: 10.3390/nano10091698 DOI Help

Authors: Michael T. Wharmby (Deutsches Elektronen-Synchrotron (DESY)) , Felicitas Niekiel (Christian Albrechts Universität zu Kiel) , Jannik Benecke (Christian Albrechts Universität zu Kiel) , Steve Waitschat (Christian Albrechts Universität zu Kiel) , Helge Reinsch (Christian Albrechts Universität zu Kiel) , Dominik Daisenberger (Diamond Light Source) , Norbert Stock (Christian Albrechts Universität zu Kiel) , Pascal G. Yot (ICGM, University Montpellier, CNRS, ENSCM)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanomaterials , VOL 10

State: Published (Approved)
Published: August 2020
Diamond Proposal Number(s): 14977 , 17668

Open Access Open Access

Abstract: The response of the metal–organic framework aluminum-1,4-cyclohexanedicarboxylate or Al-CAU-13 (CAU: Christian Albrecht University) to the application of thermal and mechanical stimuli was investigated using synchrotron powder X-ray diffraction (SPXRD). Variable temperature in situ SPXRD data, over the range 80–500 K, revealed a complex evolution of the structure of the water guest containing Al-CAU-13•H2O, the dehydration process from ca. 310 to 370 K, and also the evolution of the guest free Al-CAU-13 structure between ca. 370 and 500 K. Rietveld refinement allowed this complexity to be rationalized in the different regions of heating. The Berman thermal Equation of State was determined for the two structures (Al-CAU-13•H2O and Al-CAU-13). Diamond anvil cell studies at elevated pressure (from ambient to up to ca. 11 GPa) revealed similarities in the structural responses on application of pressure and temperature. The ability of the pressure medium to penetrate the framework was also found to be important: non-penetrating silicone oil caused pressure induced amorphization, whereas penetrating helium showed no plastic deformation of the structure. Third-order Vinet equations of state were calculated and show Al-CAU-13•H2O is a hard compound for a metal–organic framework material. The mechanical response of Al-CAU-13, with tetramethylpyrazine guests replacing water, was also investigated. Although the connectivity of the structure is the same, all the linkers have a linear e,e-conformation and the structure adopts a more open, wine-rack-like arrangement, which demonstrates negative linear compressibility (NLC) similar to Al-MIL-53 and a significantly softer mechanical response. The origin of this variation in behavior is attributed to the different linker conformation, demonstrating the influence of the S-shaped a,a-conformation on the response of the framework to external stimuli.

Journal Keywords: metal–organic frameworks; Al-CAU-13; thermal stimulus; mechanical stimulus; synchrotron powder X-ray thermodiffraction; in situ high pressure synchrotron powder X-ray diffraction

Subject Areas: Chemistry, Materials

Instruments: I15-Extreme Conditions

Other Facilities: Swiss Norwegian Beam Line at ESRF