News AG Wegner
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 theor the hompage of the .
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 cycloparaphenylene (CPP) nanobelt encircling the C59N• has been developed. This method allowed tracing of a characteristic triplet signal of C59N•⊂CPP even after several weeks. DOI: 10.1002/anie.201909126
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
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.
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.
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.
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.
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.
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.
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
We wish you a successful year and that you keep enjoying your time in the Wegner group!