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Dr. Julian Holstein and Prof. Guido Clever from the Department of Chemistry and Chemical Biology at TU Dortmund University are working with scientists from the University of Vienna to establish a method to elucidate complex molecular structures more quickly and easily. Instead of X-ray photons – which are normally used to determine the structures – electrons are diffracted on the crystal. This means that even tiny crystals of a substance under examination can now be used. The international research project has now been presented as the cover story in the renowned journal Nature Reviews Chemistry.
Molecular structures are usually determined using X-ray diffraction on single crystals. This method makes it possible to establish the three-dimensional structure of complex substances in the crystal lattice and derive a wide range of information, such as the arrangement of the atoms and the expected chemical reactivity of the compound. X-ray diffraction is therefore the standard method of characterizing unknown substances. The challenge here is that the crystals of the substances under examination must be of a suitable size. This is why researchers often fail to determine a substance’s structure.
New method reduces sample size requirements
With electron crystallography, on the other hand, electrons are diffracted on the crystal instead of X-ray photons. “What makes this method special is that we can use tiny, crystalline particles with sizes in the range of 100-1000 nanometers,” says Dr. Julian Holstein, who is the correspondent author of the article alongside Dr. Tim Grüne from the University of Vienna. As a result, powdery, crystalline deposits, which can often even be found in raw products that are still contaminated, become accessible as samples. These particles cannot be seen with the naked eye or even with extremely powerful optical microscopes. “Even samples that are unsuitable for high-brilliance synchrotron radiation due to their small crystal size can be examined using electron diffraction. Due to less stringent demands on sample size, we are also able to shorten the very time-consuming crystallization processes in the laboratory,” adds Dr. Julian Holstein. As a result, this method also has a lot of interesting potential for other scientific areas such as materials science or pharmacy.
Hydrogen atoms can be recognized more easily
Electron diffraction also offers yet another advantage. Using this method, very light hydrogen atoms, which often play a key role in both chemical reactions and biological processes, can be detected particularly effectively. What’s more, the oxidation state of certain elements in the crystal can be experimentally determined, which was previously not possible. This opens up new research opportunities in the field of catalyst research, hydrogen storage and drug development.
Prof. Guido Clever, Professor of Bioinorganic Chemistry at TU Dortmund University and one of the authors of the project says: “We are enthusiastic about the results of the measurements we carried out on our samples at ETH Zurich and the University of Vienna. We are confident that this method can lead to a series of previously inaccessible results in the areas of functional molecules and materials, solvation science and drug research.”
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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 South Campus), and from B 1 / A 40 “Dortmund-Dorstfeld” (closer to North Campus). 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 North Campus to South Campus by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at North Campus 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 15 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 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 H-Bahn is one of the hallmarks of TU Dortmund University. There are two stations on North Campus. 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 South Campus) Eichlinghofen. The other station is located at the dining hall at North Campus and offers a direct connection to South Campus every five minutes.
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”.