Research

Bidentate Lewis Acids Catalysis

Nature shows in every living system the power of catalysis. The high effectiveness and selectivity in Natures chemistry is without comparison. One trick Nature uses is the effect of multidentate binding, meaning that the substrates are hold in place by multiple interactions.

We learned from Nature by designing bidentate Lewis acids as new catalysts for Organic Synthesis. We illustrated the principle by developing the first catalyzed inverse electron-demand Diels-Alder (IEDDA) reaction of 1,2-diazines by a bidentate Lewis acid. We have also been able to incorporate such bidentate Lewis acid catalyzed IEDDA reactions in domino transformations.

We also applied our method for the preparation of novel electrolytes, diazaquinones, for organic flow battery applications. Furthermore, we could extend the concept of bidentate catalysis to other processes, such as the activation of carbon dioxide CO2 or the release of hydrogen from ammonia borane.

Boron-Nitrogen materials

Based on the simultaneous interaction of bis-boron compounds with dinitrogen, we could access novel scaffold with unique properties, such as B,N-acenes or stable neutral diradicals.

Recent Publications

"Combining Bidentate Lewis Acid Catalysis and Photochemistry: Formal Insertion of o-Xylene into an Enamine Double Bond", S. Ahles, J. Ruhl, M. A. Strauss, H. A. Wegner, Org. Lett., 2019, 21, 11, 3927-3930; DOI: 10.1021/acs.orglett.9b01020.

"Control of excited state conformation in B,N‐acenes", Z. Lu, H. Quanz, J. Ruhl, G. Albrecht, C. Logemann, D. Schlettwein, P. R. Schreiner, H. A. Wegner, Angew. Chem. Int. Ed., 2019, 58, 4259-4263; DOI: 10.1002/anie.201814104.

Cycloparaphenylenes (CPPs)

Carbon materials are gaining increased interest, especially as new materials. The control on the molecular level allows to precisely tune their properties. In this context we explore unique structures such as the class of macrocyclic cycloparaphenylenes (CPPs). Besides establishing new synthetic strategies, for instance relying on flow chemistry, to efficiently access this compound class we study their supramolecular interactions.

Organic on-surface-synthesis

In collaboration we envision to establish reliable processes to prepare nanocarbons directly on surface in a efficient and selective manner. Special focus is on the elucidation of mechanism of these on-surface-syntheses and the utilization of this knowledge to create novel transformations.

Recent Publications

"Long-lived azafullerenyl radical stabilized by supramolecular shielding with a [10]cycloparaphenylene", A. Stergiou, J. Rio, J. H. Griwatz, D. Arcon, H. A. Wegner, C. Ewels, N. Tagmatarchis, Angew. Chem. Int. Ed., 2019, ASAP, DOI: 10.1002/anie.201909126.

"Adsorption Structure of Mono- and Diradicals on a Cu(111) Surface: Chemoselective Dehalogenation of 4-Bromo-3″-iodo-p-terphenyl", D. Ebeling, Q. Zhong, T. Schlöder, J. Tschakert, P. Henkel, S. Ahles, L. Chi, D. Mollenhauer, H. A. Wegner, A. Schirmeisen, ACS NANO, 2019, 13, 324-336; DOI: 10.1021/acsnano.8b06283

Controlling structure on the molecular levels enables also controlling function in the macroscopic world. Especially interesting are geometries which can be reversibly altered between two, or even more states.

In this respect we synthesize and investigate molecular entities with multiples switching units, which are arranged in a cycle. Such an assembly induces changes from 2D to 3D. Additionally, the connectivity allows to control the switching process and to probe mechanistic insights, which are difficult with their linear counterpart. 

We developed efficient syntheses for various azobenzene macrocycles, presenting a ternary chiroptical switch, a switchable gel material or a molecular logic gate.

Azobenzenes also represent a powerful tool to study fundamental interactions, such as London dispersion.

The understanding of factors to tune stability, efficiency, as well as energetic issues is utilized to design novel materials for molecular solar thermal storage systems.

Recent Publications

"Exploring London dispersion and solvent interactions at alkyl-alkyl interfaces using azobenzene switches", M. A. Strauss, H. A. Wegner, Angew. Chem. Int. Ed., 2019, ASAP ; DOI: 10.1002/anie.201910734

"Intermolecular London Dispersion Interactions of Azobenzene Switches for Tuning Molecular Solar Thermal Energy Storage Systems", A. Kunz, A. H. Heindl, A. Dreos, Z. Wang, K. Moth-Poulsen, J. Becker, H. A. Wegner, ChemPlusChem, 2019, 84, 1145-1148; DOI: 10.1002/cplu.201900330