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  2. Abstract

Invited for the cover of this issue is the group of Roland Fischer at Ruhr University Bochum. The cover image shows that the structure/properties of materials vary as the complexity of the framework is increased and different metals are combined in single-phased MOFs.

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What was the biggest challenge in the work presented?

Multicomponent metal–organic frameworks (MC-MOFs) are exciting but complex materials to investigate. The introduction of a second metal into the monometallic framework yields a mixed-metal (MM) framework – the overall structure of the parent monometallic MOFs is preserved. Such MM-MOFs feature variations of the coordination environment of the metal ions, which bring about properties that do not follow simple correlations with respect to the composition. With a distribution of the metal cations in a single-phased framework (e.g. solid solution), the accurate structural characterization of such MC-MOFs is difficult. The biggest was using various analytical methods to understand the impact of doping with a second metal (V, in particular) and reveal the organization of these frameworks at the molecular level. This is important for adsorption-based processes or catalysis.

How did the collaboration on this project work?

The work is the result of the collaboration of the team at Ruhr University Bochum with the group of Prof. A. Pöppl (B. Jee, in particular) and PD Dr. M. Bertmer (A. V. Kuttatheyil, in particular) at the Institut für Experimentelle Physik II (Universität Leipzig), and with Dr. C. Sternemann at Fakultät Physik/DELTA (Technische Universität Dortmund). Our work on V-MOF related topics with Prof. A. Pöppl’s group started in 2009. Their expertise in EPR spectroscopy was highly valuable and provided unambiguous evidence for VIV[RIGHTWARDS ARROW]VIII reduction (Angew. Chem. Int. Ed. 2010, 49, 6212). This success has sparked further collaborations on MC-MOFs. EPR studies revealed presence of both mono- (Zn–Zn and Cu–Cu) and mixed-metal (Zn–Cu) paddle-wheel clusters in Zn/Cu MC-MOFs (Eur. J. Inorg. Chem. 2012, 1688), whose features are impossible to prove just based on single-crystal X-ray diffraction techniques (XRD). Dr. M. Bertmer and A. V. Kuttatheyilhave provided NMR data. The breathing behaviour of the presented Al/V MC-MOFs was investigated in collaboration with Dr. C. Sterneman by in situ powder XRD at the Synchrotron beamline BL9 of DELTA (under CO2 pressure in particular). We are grateful to all of our partners and look forward to continuing our successful collaboration.

In one word, how would you describe your research?


Who designed the cover?

The cover picture was designed by Olha and Olesia Kozachuk.

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