Metal Organic Frameworks - a class of crystalline, porous coordination polymers
One of the main areas of research at the Institute of Physical Chemistry is in the field of metal-organic coordination polymers, known as Metal Organic Frameworks (MOFs for short). The representatives of this class of materials are characterised by a bimodular structure consisting of inorganic nodes, so-called secondary building units (SBUs for short), and organic linker units coupled with the properties of permanent porosity and crystallinity. This makes it possible to imagine various possible applications in catalysis, gas storage, sensor technology and material separation.
The physicochemical investigation of known synthesis strategies and novel approaches, such as room temperature synthesis using the concept of the controlled SBU approach for both known and new metal-organic frameworks, is one of the research activities. Among other things, the mechanism and the synthesis conditions are investigated with regard to the requirements for crystallite size, purity and specific surface area. The MOF systems investigated include MOF-5 and HKUST-1.
In addition to research activities in the field of catalysis and conductive MOFs, one focus is on the separation of substances via the gas phase using various representatives of this class of porous coordination polymers as a stationary phase in gas chromatography. This work is being carried out as part of the priority programme 1362 of the German Research Foundation DFG in the sub-project "Liquid phase epitaxy (LPE) of functionalized SURMOFs for application in Gas Chromatography". The aim of this work is the deposition of various MOFs in thin quartz glass capillaries (length: 10-30 m, inner diameter: 0.53-0.25 mm) for use in gas chromatography. The subsequent separation performance has so far been demonstrated in the separation of various mixtures of substances, such as branched and unbranched alkanes, BTEX aromatics, Lewis-based compounds and chiral analytes.
The specific adsorption behaviour of different compounds is investigated at the institute using various methods, such as infrared spectroscopy and inverse gas chromatography. With the latter method, for example, kinetic (diffusion and mass transfer coefficients) and thermodynamic constants (adsorption enthalpies, adsorption entropies) can be determined, providing deep insights into the adsorption process.
Selected publications:
On the electrical conductivity of coordination polymers and MOFs
- D. Steinbach, S. Gersdorf, J. Heitmann, F. Mertens, "Charge Transport of Coordination Polymers Containing Rhodium Paddle-Wheel Units", accepted to Journal of Physical Chemistry dx.doi.org/10.1021/acs.jpcc.2c04632
for synthesis:
- S. Hausdorf, F. Baitalow, J. Seidel, F. Mertens, "Gaseous Species as Reaction Tracers in the Solvothermal Synthesis of the Zinc Oxide Terephthalate MOF-5", J. Phys. Chem. A 2007, 111(20), 4259-4266, dx.doi.org/10.1021/jp0708291
- S. Hausdorf, F. Baitalow, T. Böhle, D. Rafaja, F. Mertens, "Main Group and Transition Element IRMOF Homologues", J. Am. Chem. Soc. 2010, 132, 10978-10981, dx.doi.org/10.1021/ja1028777
for the deposition of MOFs on surfaces:
- A. S. Münch, M. S. Lohse, S. Hausdorf, G. Schreiber, D. Zacher, R. A. Fischer, F. Mertens, "Room Temperature Preparation Method for Thin MOF-5 Films on Metal and Fused Silica Surfaces Using the Controlled SBU Approach", Microporous and Mesoporous Materials 2012, 159, 132-138, dx.doi.org/10.1016/j.micromeso.2012.04.023
On gas chromatography with MOFs:
- A. S. Münch, F. Mertens, "HKUST-1 as an open metal site gas chromatographic stationary phase - capillary preparation, separation of small hydrocarbons and electron donating compounds, determination of thermodynamic data", J. Mater. Chem. 2012, 22, 10228-10234, dx.doi.org/ 10.1039/C2JM15596F
- A. S. Münch, J. Seidel, A. Obst, E. Weber, F. Mertens, "High Separation Performance of Chromatographic Capillaries Coated with MOF-5 by the Controlled SBU Approach", Chem. Eur. J. 2011, 17(39), 10958-10964, dx.doi.org/10.1002/chem.201100642
