Publication
Title
Sensing the framework state and guest molecules in MIL-53(Al) via the electron paramagnetic resonance spectrum of dopant ions
Author
Abstract
X-ray diffraction (XRD) and electron paramagnetic resonance spectroscopy (EPR) were combined to study the structural transformations induced by temperature, pressure and air humidity of the breathing metalorganic framework (MOF) MIL-53(Al), doped with paramagnetic VIV ions, after activation. The correlation between in situ XRD and thermogravimetric analysis measurements showed that upon heating this MOF in air, starting from ambient temperature and pressure, the narrow pore framework first dehydrates and after that makes the transition to a large pore state (lp). The EPR spectra of VIV[double bond, length as m-dash]O molecular ions, replacing AlOH in the structure, also allow to distinguish the as synthesized, hydrated (np-h) and dehydrated narrow pore (np-d), and lp states of MIL-53(Al). A careful analysis of EPR spectra recorded at microwave frequencies between 9.5 and 275 GHz demonstrates that all VIV[double bond, length as m-dash]O in the np-d and lp states are equivalent, whereas in the np-h state (at least two) slightly different VIV[double bond, length as m-dash]O sites exist. Moreover, the lp MIL-53(Al) framework is accessible to oxygen, leading to a notable broadening of the VIV[double bond, length as m-dash]O EPR spectrum at pressures of a few mbar, while such effect is absent for the np-h and np-d states for pressures up to 1 bar.
Language
English
Source (journal)
Physical chemistry, chemical physics / Royal Society of Chemistry [London] - Cambridge, 1999, currens
Publication
Cambridge : The Royal Society of Chemistry , 2017
ISSN
1463-9076 [print]
1463-9084 [online]
DOI
10.1039/C7CP04760F
Volume/pages
19 :36 (2017) , p. 24545-24554
ISI
000411606200018
Pubmed ID
28852751
Full text (Publisher's DOI)
Full text (open access)
Full text (publisher's version - intranet only)
UAntwerpen
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Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
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Creation 05.10.2017
Last edited 09.10.2023
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