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News AG Wegner

News, topics and planned events of the Wegner group are posted here.

October 7th, "Perspective isomorphs" published in Beilstein J. Org. Chem.

The Publication originated from an interdisciplinary collaboration of the Art & Chemistry departements of the JLU. The concept of the central perspective is transfered to chemistry to develop new graphical representations for molecules and atoms. The project was supported by the Schering Stiftung.

The interdisciplinary research project was designed by Prof. Dr. Ansgar Schnurr (Institute for Art Education), Prof. Dr. Hermann Wegner (Institute for Organic Chemistry), and Jannis Neumann (student of art education and biology), Justus Liebig University (JLU) Giessen.

A new classification of molecular structures, so-called perspective isomorphs, applying an interdisciplinary crossing of epistemological concepts between chemistry and art is presented. The idea originates from the notion that molecules can be classified, if they appear equivalent from one standpoint in a specific orientation. A group of such molecules was termed perspective isomorphs. The general concept was outlined together with a nomenclature system. The concept has been visualized by artistic representations of molecules from the artists Patrick Borchers, Jette Flügge, and Christoph Kern. DOI:10.3762/bjoc.15.224

The artistic sketches were also part of an exhibition at the central library of the university Giessen. Further information concerning the exhibition is online available at the Giessener Anzeiger or the hompage of the Schering Stiftung.

September 26th, Two new publications in Angewandte Chemie!

The two publications with the titles: "Long-lived azafullerenyl radical stabilized by supramolecular shielding with a [10]cycloparaphenylene" and "Exploring London dispersion and solvent interactions at alkyl-alkyl interfaces using azobenzene switches" are now available online as accepted article in Angew. Chem. Int. Ed..

In collaboration with the groups of Dr. N. Tagmatarchis, Dr. C. P. Ewels and Prof. Dr. D. Arčona an innovative radical shielding approach based on supramolecular complexation, using the protection offered by a [10]cycloparaphenylene ([10]CPP) nanobelt encircling the C59N• has been developed. This method allowed tracing of a characteristic triplet signal of C59N•⊂[10]CPP even after several weeks. DOI: 10.1002/anie.201909126

Angew_Griwatz_2019

For another study London dispersion in conjunction with solvent interactions between linear alkyl chains were examined by an azobenzene-based setup. Investigations via 1H NOESY NMR indicate additional long-range interactions with the opposite phenyl core in the Z-state. This work provides a rare insight into the stabilizing contributions of highly flexible groups in an intra- as well as intermolecular setting. DOI: 10.1002/anie.201910734

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July 15th, Goodbye Dr. Sebastian!

Sebastian Ahles obtained his doctoral degree today. For his Thesis, he mainly worked on new Applications of the Inverse Electron Demand Diels-Alder (IEDDA) reaction and successfully merged it with a photochemical approach.

The members of the Wegner group wants to express their gratitude for his continuous support and wishes him all the best for his future career. At the moment, he pursuits further studies as a postdoc in the group of Urs Gellrich.

July 5th, New member of the committee on "Kinetics and reaction mechanisms" of the DECHEMA

Hermann Wegner has been appointed as a member of the committee on "Kinetics and reaction mechanisms" of the DECHEMA.

May 13th, New Paper in Org. Lett. selected as Editors' Choice.

In the publikation with the title "Combining Bidentate Lewis Acid Catalysis and Photochemistry: Formal Insertion of o-Xylene into an Enamine Double Bond" a new reaction pathway for o-quinodimethane derivatives upon irradiation with blue LEDs is presented.

A bidentate Lewis acid catalyzed domino inverse-electron-demand Diels–Alder reaction combined with a photoinduced ring opening formally inserts o-xylene moieties into enamine double bonds. After reduction, phenethylamines were obtained in good yields. The scope of the reaction was determined by variation of all three starting compounds: phthalazines, aldehydes, and amines.

The results were published as open access article in Organic Letters and were selected as ACS Editors' Choice.

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May 1st, New bachelor student Conrad welcomed.

The Wegner group welcomes its new new bachelor candidate Conrad Averdunk.

He has just started his studies of meta-trisazobenzenes as a molecular triple photoswitch with selectively and independently switchable subunits. We hope, that you will enjoy your time in the Wegner group.

April 30th, Research stay of Assoc. Prof. Yakimova.

From February, 1st until April 30th, 2019, Assoc. Prof. Yakimova stayed at the Justus-Liebig University Giessen under the DAAD program Stimuli-responsive macrocyclic assembly induced by complexation of molecular switches.

In the context of the scientific exchange between the Justus Liebig University Giessen and the Kazan Federal University, Assoc. Prof. Yakimova has been a guest of the Wegner group from February, 1st until April 30th, 2019. She stayed at the Justus-Liebig University Giessen under the DAAD program Stimuli-responsive macrocyclic assembly induced by complexation of molecular switches.

February 28th, Publication in J. Chem. Phys. marked as Editor's Pick!

In collaboration with the group of Prof. Lars H. Andersen "Action-spectroscopy studies of positively charge-tagged azobenzene in solution and in the gas-phase" were conducted. Our results were published in the Journal of Chemical Physics. The investigation demonstrates the potential of this technique to provide the intrinsic absorption properties of the ammonium-tagged azobenzene.

The absorption of a positively charge-tagged azobenzene molecule is studied in the gas-phase by measuring photoinduced fragmentation of ions as a function of time. This technique provides information on prompt as well as delayed fragmentation, and a single dissociation channel after one-photon absorption is identified. The spectra in solution, as well as in the gas-phase, show a weak S0 → S1, a strong S0 → S2, and a broad absorption band in the UV regime. The bands are assigned through time-dependent density functional theory calculations. The ratio of the various absorption bands depends on the trans to cis isomerization fraction and may be tuned by light irradiation. Gas-phase absorption spectra are presented and discussed in terms of trans and cis isomers.

DOI: 10.1063/1.5085743

February 14th, Application of Air-stable Bisborane catalyst in Total Synthesis Reported.

Recently, Burns and co-workers reported the successful implementation of the air-stable catalyst complex of 9,10-dimethyl-9,10-diboraanthracene with pyridazine in their total synthesis of azamerone.

Their "Enantioselective Synthesis of Azamerone" published in JACS demonstrated the applicability of the air-stable bisboron complex as a powerful tool to catalyse Inverse Electron Demand Diels-Alder(IEDDA) reactions even at a late stage in total synthesis. Especially the possibility to establish IEDDA reactions between tetrazines and electron deficient 1,4-naphthoquinones can be very auspicious to introduce a 2,3-diaza-anthraquinone motif into complex molecular structures.

January 31st, Farewell of our Apprentice Elena.

After the successful completion of her apprenticeship as the best of her class, Elena Berger left the Justus-Liebig University Giessen to pursue her career in industry at the Panacol- Elosol GmbH. The Wegner group likes to express its gratitude for her commitment and for supporting science. We wish her all the best for her future. Goodbye Elena!

January 21st, First Publication for 2019 online!

The investigation of B,N-acenes was conducted together with the groups of P. R. Schreiner and D. Schlettwein. The paper with the title "Control of excited state conformation in B,N-acenes" was published in Angewandte Chemie and is now online available.
Herein we show a new concept to control conformation in molecules in the excited state through
harvesting negative hyperconjugation. The strategy was realized with the 2,3,1,4-benzodiazadiborinane scaffold that was prepared by a new synthetic protocol. Photochemical studies identify dual light emission that can be assigned to originate from well-defined conformers. The emission at longer wavelength can be switched off by restricting the rotational degrees of freedom in the solid-state as well as by controlling the energy level of the excited states through solvent polarity.
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January 17th, Research Article Highlighted by Press Office of the JLU.

One recent publication in 2018 of the Wegner group draw the attention of the press office of the JLU. As a result, the work was highlighted in a press release on the university homepage. As additional advantage, this release provides a comprehensive description of the work in German. See below for further information:

Link to the Press Release: http://www.uni-giessen.de/ueber-uns/pressestelle/pm/pm10-19

 

Details to the original publication:

"An Amine Group Transfer Reaction Driven by Aromaticity", S. Ahles, S. Götz, L. Schweighauser, M. Brodsky, S. N. Kessler, A. H. Heindl, H. A. Wegner, Org. Lett., 2018, 20, 7034-7038; DOI: 10.1021/acs.orglett.8b02967

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January 3rd, New co-workers in 2019 welcome!

The Wegner group welcomes its new co-workers Julia Ruhl and Jan Griwatz, who started their PhD studies in the fields of Boron based Lewis acid catalysis and cycloparaphenylenes respectively.

We wish you  a successful year and that you keep enjoying your time in the Wegner group!