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Research

Outline

Metal-organic frameworks (MOFs) represent a diverse and highly tuneable family of inorganic-organic hybrid materials exhibiting large specific surface areas and huge pore volumes. The zeolite-like architectures are composed of metal ions, which are interconnected by organic linker molecules (multivalent carboxylates, imidazolates, etc.) to generate two- or three-dimensional extended networks.

Grafikillustration © AK-Henke​/​TU Dort­mund

Based on a large variety of molecular building units an almost infinite number of MOFs could in principle be synthesised. Simple exchange of the inorganic and/or the organic units allows for a targeted tuning of the framework properties by means of synthetic chemistry. In view of their huge potential for various applications such as hydrogen storage, carbon dioxide capture, catalysis or drug delivery, MOFs attract tremendous interest from academia as well as industry.

Rational synthesis of functionalised metal-organic frameworks

Via rational design of the organic linkers we aim to design the structure as well as the functional properties of MOFs. Currently we are developing synthetic strategies for alkali ion based MOFs. MOFs based on group 2, d-block, group 13 or lanthanide ions are abundant, while alkali-MOFs are extremely rare. Such materials, however, are interesting for electrochemical energy storage or as solid electrolytes and further open up new pos­si­bi­lities because they can be processed from aqueous solution.

Grafikillustration © AK-Henke​/​TU Dort­mund

Understanding responsive metal-organic frameworks

We study the responsive behaviour of MOFs with respect to guest inclusion, changes in temperature or application of mechanical pressure with state-of-the-art X-ray diffraction (XRD) and gas/vapour sorption techniques. Our XRD experiments are often done in situ with highly intense synchrotron radiation either at the Dort­mund synchrotron DELTA or at larger facilities such as DESY (Hamburg) or Diamond Light Source (near Oxford, UK).

Grafikillustration © AK-Henke​/​TU Dort­mund

Just recently, we discovered that specific MOFs based on tetrahedrally coordinated divalent metal ions (Zn2+ or Co2+) and imidazolate linkers switch from an open to a closed form when compressed hydrostatically. In this process, no chemical bond is broken while the crystals reduce their volume by more than 20%. Once the pressure is released, the MOFs return to the open pore form. Such transitions may pave the way for applications of MOFs as shock absorbers, nanodampers or for solid-state refrigeration applications.

Grafikillustration © AK-Henke​/​TU Dort­mund

”Pore closure in zeolitic imidazolate frameworks under mechanical pressure”
S. Henke et al. Chem. Sci. 2018, 9, 1654-1660.

Porous metal-organic framework liquids and glasses

MOF glasses represent a very new class of functional materials which can be obtained from meltable MOFs by vitrification of the melt. MOFs liquids and glasses have a major advantage against their crystalline counterparts, as they can be processed and shaped into different forms before vitrification to porous MOF glasses. Surprisingly, there are only little more than a handful of MOFs which can be melted and transformed into glasses. Thousands of other MOFs simply decompose upon heating without melting.

We want to understand the chemical and structural features, which are required to melt MOFs. We further look into the textural properties (porosity, pore size, surface area, etc.) of MOF glasses, which we want to tune by building block design. Recently, we prepared the very first cobalt-based zeolitic imidazolate framework (ZIF) that can be melted and transformed into a nanoporous glass. These findings might pave the way for the application of liquid and glassy MOFs in gas separation processes and catalysis.

Grafikillustration © AK-Henke​/​TU Dort­mund

”Porous purple glass - A cobalt imidazolate glass with accessible porosity from a meltable cobalt imidazolate framework”
L. Frentzel-Beyme et al. J. Mater. Chem. A 2019, 7, 985-990.

"Meltable Mixed-Linker Zeolitic Imidazolate Frameworks and Their Microporous Glasses - From Melting Point Engineering to Selective Hydrocarbon Sorption”
L. Frenzel-Beyme et al. J. Am. Chem. Soc. 2019, 141, 12362-12371.

Location & approach

The campus of TU Dort­mund University is located close to interstate junction Dort­mund West, where the Sauerlandlinie A 45 (Frankfurt-Dort­mund) crosses the Ruhrschnellweg B 1 / A 40. The best interstate exit to take from A 45 is "Dort­mund-Eichlinghofen" (closer to Campus Süd), and from B 1 / A 40 "Dort­mund-Dorstfeld" (closer to Campus Nord). Signs for the uni­ver­si­ty are located at both exits. Also, there is a new exit before you pass over the B 1-bridge leading into Dort­mund.

To get from Campus Nord to Campus Süd by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at Campus Nord and use the H-Bahn (suspended monorail system), which conveniently connects the two campuses.

TU Dort­mund University has its own train station ("Dort­mund Uni­ver­si­tät"). From there, suburban trains (S-Bahn) leave for Dort­mund main station ("Dort­mund Hauptbahnhof") and Düsseldorf main station via the "Düsseldorf Airport Train Station" (take S-Bahn number 1, which leaves every 20 or 30 minutes). The uni­ver­si­ty is easily reached from Bochum, Essen, Mülheim an der Ruhr and Duisburg.

You can also take the bus or subway train from Dort­mund city to the uni­ver­si­ty: From Dort­mund main station, you can take any train bound for the Station "Stadtgarten", usually lines U41, U45, U 47 and U49. At "Stadtgarten" you switch trains and get on line U42 towards "Hombruch". Look out for the Station "An der Palmweide". From the bus stop just across the road, busses bound for TU Dort­mund University leave every ten minutes (445, 447 and 462). Another option is to take the subway routes U41, U45, U47 and U49 from Dort­mund main station to the stop "Dort­mund Kampstraße". From there, take U43 or U44 to the stop "Dort­mund Wittener Straße". Switch to bus line 447 and get off at "Dort­mund Uni­ver­si­tät S".

The H-Bahn is one of the hallmarks of TU Dort­mund University. There are two stations on Campus Nord. One ("Dort­mund Uni­ver­si­tät S") is directly located at the suburban train stop, which connects the uni­ver­si­ty directly with the city of Dort­mund and the rest of the Ruhr Area. Also from this station, there are connections to the "Technologiepark" and (via Campus Süd) Eichlinghofen. The other station is located at the dining hall at Campus Nord and offers a direct connection to Campus Süd every five minutes.

The AirportExpress is a fast and convenient means of transport from Dort­mund Airport (DTM) to Dort­mund Central Station, taking you there in little more than 20 minutes. From Dort­mund Central Station, you can continue to the uni­ver­si­ty campus by interurban railway (S-Bahn). A larger range of in­ter­na­tio­nal flight connections is offered at Düsseldorf Airport (DUS), which is about 60 kilometres away and can be directly reached by S-Bahn from the uni­ver­si­ty station.

The facilities of TU Dort­mund University are spread over two campuses, the larger Campus North and the smaller Campus South. Additionally, some areas of the uni­ver­si­ty are located in the adjacent "Technologiepark".

Site Map of TU Dort­mund University (Second Page in English).