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Metal-organic frameworks

Metal-organic frameworks (MOFs) are a developing class of functional, porous materials with promising applications in gas storage and separation, (photo-)catalysis, heat transformation, chemical sensing, purification and decontamination, to name only a few. Their composition involves elements from classical inorganic chemistry, complex chemistry and organic chemistry, leading to a large variety of compounds enabling also to specifically tune the systems for a desired function. The key factor for their reactivity is the presence of pores or cavities in their molecular structure. This arrangement leads to light weight and yet mechanically and thermally stable materials with enhanced surface areas. The cavities can be regions for highly selective material adsorption, reaction chambers for catalytic processes or they can simply constitute channels that only permit the passage of defined molecules.

Chromophores in MOFs

The theory projects within the ModISC research training group (RTG 2482) examine the absorption and emission properties of organic and metal organic chromophores in vacuum and embedded in various surroundings. The MOF studies in our group were motivated by fluorescence measurements performed in the group of Prof. Janiak at HHU that showed increased fluorescence intensity when the chromophore methylisoalloxazine (MIA) was incorporated into the MIL53as framework (Figure 2).

Force-field computations indicate slightly different orientations of MIA within the pore and an overall increase of the unit cell volume (by ca. 485 Å3 ~ 4.4%) when assuming full coverage. We aim to further model the properties of MIA in various MOFs using excited state quantum chemistry tools in combination with force field methods.

Gas Adsorption and Separation

Certain MOFs show a high affinity and selectivity for the adsorption of gas molecules. We investigate these properties by a combination of plane-wave and force-field techniques. These methods allow us to identify binding sites for gas molecules within the MOF2 and to obtain the adsorption properties by means of adsorption isotherms.

Read more about MOFs and our modeling of their properties

  1. The Promise of Metal–Organic Frameworks for Use in Liquid Chromatography. Bell, D. S. . LCGC North Am. 36, 352–354 (2018).

  2.  Metal-organic frameworks with potential application for SO2-Separation and flue gas desulfurization. Philipp Brandt, Alexander Nuhnen, Marcus Lange, Jens Möllmer, Oliver Weingart and Christoph Janiak. ACS Appl. Mater. Interfaces, 11, 17350–17358 (2019), DOI: 10.1021/acsami.9b00029

  3. Coordinatively Unsaturated Metal Sites (Open Metal Sites) in Metal-Organic Frameworks: Design and Applications. Kökçam-Demir, Ü., Goldman, A., Esrafili, L., Gharib, M., Janiak, C., Weingart, O. & Morsali, A.Chem. Soc. Rev. accepted (2020), DOI: 10.1039/c9cs00609e

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