Introducing a photo-switchable azo-functionality inside Cr-MIL-101-NH2 by covalent post-synthetic modification
Antje Modrow1, Dordaneh Zargarani, Rainer Herges
1Institut für Anorganische Chemie, Christian-Albrechts-Universität, Max-Eyth-Strasse 2, D-24118 Kiel, Germany.
Dalton Transactions (Cambridge, England : 2003)
|June 14, 2012
Summary
Researchers covalently introduced azo functionality into a metal-organic framework (MOF) using post-synthetic modification. This azo-functionalized MOF exhibits light-induced cis/trans isomerization, altering its methane sorption properties.
Area of Science:
- Materials Science
- Chemistry
- Nanotechnology
Background:
- Metal-organic frameworks (MOFs) offer tunable porosity for diverse applications.
- Post-synthetic modification (PSM) allows for the introduction of new functionalities into pre-formed MOFs.
- Azo-containing molecules can undergo light-induced isomerization, enabling responsive materials.
Purpose of the Study:
- To covalently introduce azo functionality into the Cr-MIL-101 MOF via PSM.
- To investigate the impact of azo group incorporation on the MOF's structural integrity and properties.
- To explore the light-responsive behavior and gas sorption changes of the functionalized MOF.
Main Methods:
- Post-synthetic modification of Cr-MIL-101-NH(2) with p-phenylazobenzoylchloride and 4-(phenylazo)phenylisocyanate.
- Characterization using X-ray powder diffraction (XRPD), N(2) sorption, IR spectroscopy, and NMR spectroscopy.
- UV/Vis spectroscopy to monitor cis/trans isomerization and methane adsorption measurements to assess sorption property variations.
Main Results:
- Successful covalent introduction of azo groups into Cr-MIL-101, forming Cr-MIL-101_amide and Cr-MIL-101_urea, without framework collapse.
- Demonstration of light-induced cis/trans isomerization of the incorporated azo functionalities via UV/Vis spectroscopy.
- Observed variations in methane sorption properties correlated with the cis/trans isomerization of the azo groups.
Conclusions:
- Azo functionality can be successfully and covalently integrated into MOFs via PSM, creating novel responsive materials.
- The light-induced isomerization of azo groups within the MOF can modulate its gas sorption behavior.
- This work opens avenues for designing light-switchable MOFs for applications in gas storage and separation.
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