Robby Vroemans

Nature Synthesis, Published online: 02 January 2023; doi:10.1038/s44160-022-00195-1

Cross-coupling between two different C–H bonds with the release of hydrogen is a powerful yet challenging transformation. Catalytic methods that harness photo- or electrochemistry facilitate thermodynamically unfavourable coupling reactions under mild conditions. This Perspective outlines strategies based on photoinduced hydrogen-atom transfer for the cross-coupling of various hydrocarbons.

SASSY NMR is a novel 2-in-1 technique capable of observing solid and solution phases simultaneously. Gel-like material appears in both fractions with a distribution proportional to the rigidity of the C−H dipoles. SASSY is advantageous when monitoring processes involving multiphase changes, as traditional sequential solid and solution NMR can miss rapid fluctuations. SASSY is easy to use, time efficient and can be applied universally.

Abstract

Synergism between different phases gives rise to chemical, biological or environmental reactivity, thus it is increasingly important to study samples intact. Here, SASSY (SimultAneous Solid and Solution spectroscopY) is introduced to simultaneously observe (and differentiate) all phases in multiphase samples using standard, solid-state NMR equipment. When monitoring processes, the traditional approach of studying solids and liquids sequentially, can lead to information in the non-observed phase being missed. SASSY solves this by observing the full range of materials, from crystalline solids, through gels, to pure liquids, at full sensitivity in every scan. Results are identical to running separate ¹³C CP-MAS solid-state and ¹³C solution-state experiments back-to-back but requires only a fraction of the spectrometer time. After its introduction, SASSY is applied to process monitoring and finally to detect all phases in a living freshwater shrimp. SASSY is simple to implement and thus should find application across all areas of research.

Nature Reviews Chemistry, Published online: 01 January 2023; doi:10.1038/s41570-022-00451-0

Twenty five years ago, Christopher Lipinski and colleagues published arguably the most influential sentence in small-molecule drug discovery. Their cleverly crafted ‘rule of 5’ (Ro5) mnemonic was adopted into everyday medicinal chemistry practice and has influenced a generation of small-molecule drug discovery scientists. Five times five years later, we consider the impact of the Ro5 and ask to what extent it should still guide today’s medicinal chemistry efforts.

Levulinic acid conversion was studied on Ru/SrZrO₃ and Ru/BaZrO₃ catalysts, where the principal focus was the perovskite's basicity effect on the activity and selectivity into value-added chemicals. The results shown that LA conversion is associated to higher strength of the basic sites of Ru/BaZrO₃, and the formation of GVL was proposed to proceed via the intermediacy of 4-hydroxypentanoic acid.

Abstract

The catalytic performance of Ru impregnated perovskites-based catalysts (Ru/SrZrO₃ and Ru/BaZrO₃) in the conversion of levulinic acid (LA) into higher valuable chemicals was carried out at different reaction temperatures. The Ru/SrZrO₃ and Ru/BaZrO₃ catalysts, with a loading of 2.0 Ru atoms nm⁻², were prepared by incipient impregnation, and characterized by different techniques. The characterization results indicate presence of dispersed Ru catalysts, with a crystalline structure, with absence of carbonate species for Ru/SrZrO₃ and larger carbonates as segregated phase and with stronger basic sites for Ru/BaZrO₃. At higher reaction temperatures (200 °C – 250 °C), the higher strength of the basic sites of Ru/BaZrO₃ had a direct influence on the levulinic acid (LA) conversion reaction. Differences in the apparent activation energy (E_ap) values follow the same trend. The catalysts produce a 100 % of selectivity towards GVL. The formation of GVL was proposed to proceed via the intermediacy of 4-hydroxypentanoic acid due to the presence of basic surface sites.

Nature, Published online: 20 December 2022; doi:10.1038/d41586-022-04555-x

Researchers have never found fossils of dinosaurs’ sound-producing organs. Plus, South Korea’s lunar orbiter has arrived at the Moon and a historic global deal to save species.

Nature, Published online: 20 December 2022; doi:10.1038/d41586-022-04479-6

Fossils of adult and infant ichthyosaurs suggest that the ocean-going giants congregated to have their young.

Publication date: 1 March 2023

Source: Coordination Chemistry Reviews, Volume 478

Author(s): Shuzhen Lv, Huijie Wang, Yuting Zhou, Dianping Tang, Sai Bi

A new generation of solid superbases derived from potassium single atoms is described by You Han, Lin-Bing Sun, and co-workers in their Research Article (e202215157). The source of basicity is different from conventional basicity originating from oxygen and nitrogen atoms. Because of the superbasicity as well as high dispersion and anchoring of the basic sites, the potassium single atoms on graphene exhibit excellent catalytic activity and stability in transesterification reactions.