Matthias Bechmann

Our group has recently introduced chiral isotelluroureas as a new class of Lewis base catalysts, which show increased nucleophilicity and basicity as compared to the lighter chalcogen-based congeners within the family of isochalcogenoureas. This short perspective article aims to introduce the readers to these novel catalysts which show promising reactivity profiles and allow for increased reaction rates, thus making them particularly appealing for applications where some of the established isothioureas or isoselenoureas may not be nucleophilic enough and thus reach their limits.

The limitations of fossil fuel feedstocks, which are the main sources of starting materials for most polymer synthesis, necessitate the development of new, more sustainable synthesis routes and materials. An alternative could be biological feedstocks, such as plants and their products, for example, plant oils and their fatty acids. In this study, we synthesized and characterized new graft-polymer and crosslinked polymer networks from fatty acids and poly(2-isopropenyl-2-oxazoline) (PiPOx). The reaction was performed without solvents or catalysts and does not lead to any by-products, reducing the amount of waste material produced during the formation of the materials. The ring-opening reaction of the 2-oxazoline ring of PiPOx with carboxylic acids was analyzed by 1H‑NMR and FTIR spectroscopy, as well as monitored by rheology and was observed to be fast, clean and quantitative. Crosslinking through an addition reaction of diacid with pendant 2-oxazoline groups of PiPOx was observed to increase the mechanical strength of the polymers considerably. To further enhance the material's sustainability, waste cooking oil (WCO) was used as a source, with the final materials having a waste-feedstock content of 66‑67 wt%. This work thus demonstrates an efficient and sustainable approach to convert fatty acids into advanced polymer networks, offering significant potential for environmentally friendly material technologies.

TeHyperBTM [= (2 S ,3 R )‐3‐isopropyl‐2‐phenyl‐3,4‐dihydro‐2 H ‐benzo[4,5][1,3]tellurazolo[3,2‐a]pyrimidine] is introduced as a novel, highly effective, chiral, Lewis basic isochalcogenourea organocatalyst. Compared to its established sulphur‐ and selenium‐based homologues HyperBTM and SeHyperBTM, the increased nucleophilicity and Lewis basicity of TeHyperBTM directly impact its catalytic performance by increasing reaction rates and often also improving enantioselectivities for organocatalytic (4 + 2)‐cycloadditions between Michael acceptors and electron‐deficient allenes or alkynes. Furthermore, less reactive reagents, such as diethyl allenylphosphonate or ethyl but‐2‐ynoate, that were not sufficiently activated by HyperBTM and SeHyperBTM catalysts, underwent smooth (4 + 2)‐cycloadditions with Michael acceptors when using TeHyperBTM as the catalyst, which underscores the high catalytic potential of this novel chiral highly nucleophilic Lewis base.

Radio amplification using stimulated emission of radiation (RASER) effects in the NMR can increase NMR signals over time due to a feedback loop between the sample magnetization and the probe coil coupled with radiation damping (RD). Previously, RD rates had been directly observed only for the ¹H, ³He, ¹⁷O and ¹²⁹Xe nuclei. We report that experimental direct measurements of an NMR RASER to determine RD time constants for the three heteronuclei (¹³³Cs (I = 7/2), ⁷Li (I = 3/2) and ³¹P (I = 1/2)) in a highly concentrated solution from the NMR RASER emissions using a conventional NMR probe. Under conditions where the RD rate exceeds the transverse relaxation rate (i.e., the NMR RASER condition is fulfilled), we recorded both the transverse NMR RASER response to imperfect inversion and the recovery of longitudinal magnetization. The data were directly evaluated based on the well-known Bloom model as estimated RD rate constants of 8.0, 1.8 and 25 Hz for ¹³³Cs, ⁷Li and ³¹P, respectively. The proposed method can be applied to observe RD rate constants for the other nuclei as well.

The majority of energy storage devices like batteries, fuel cells or electrolyzers require heterogeneous electrodes. Immobilization of redox‐active organic molecules by a polymeric approach seems to be a promising route towards organic electrodes for electrocatalytic energy storage or in batteries. Although numerous reports on synthesis and application of new poly‐anthraquinones exist, a universal guideline or tool for selection of the best polymer, concerning several energy storage applications, is still underdeveloped. Moving into the direction of developing such a tool, we have selected and synthesized three poly(anthraquinones). NMR, FTIR, UV‐Vis, TGA, contact angle measurement and SEM revealed certain structure‐property trends, which can be correlated with the performance in the electrochemical investigation. The insights gained within this work demonstrate correlations between the FTIR frequencies and the electrochemical reduction potential, as well as between the polymer hydrophobicity and the electrochemical performance.

A novel route to highly aromatic polyimides is presented and is used to form multiblock copolymers which is inherently difficult to achieve via traditional routes for this important polymer family.

A major breakthrough in speed and sensitivity of 2 D spin‐noise‐detected NMR is achieved owing to a new acquisition and processing scheme called “double block usage” (DBU) that utilizes each recorded noise block in two independent cross‐correlations. The mixing, evolution, and acquisition periods are repeated head‐to‐tail without any recovery delays and well‐known building blocks of multidimensional NMR (constant‐time evolution and quadrature detection in the indirect dimension as well as pulsed field gradients) provide further enhancement and artifact suppression. Modified timing of the receiver electronics eliminates spurious random excitation. We achieve a threefold sensitivity increase over the original snHMQC (spin‐noise‐detected heteronuclear multiple quantum correlation) experiment (K. Chandra et al., J. Phys. Chem. Lett. 2013, 4, 3853) and demonstrate the feasibility of spin‐noise‐detected long‐range correlation.