Meeting the UN Sustainable Development Goals with Mechanochemistry.

Chemistry traditionally relies on reactions in solution, but this method is increasingly problematic due to the scale of chemical processes and their economic and environmental impact. Handling residual chemical waste, including solvents, incurs significant costs and environmental pressure. Conversely, novel chemical approaches are needed to address pressing societal issues such as climate change, energy scarcity, food insecurity, and waste pollution.

Supramolecular intermediates in thermo-mechanochemical direct amidations.

We present a solvent-free thermo-mechanochemical approach for the direct coupling of carboxylic acids and amines, which avoids activators and additives. Detailed analysis of the reactions by and monitoring methods led to the observation, isolation, and characterisation of multicomponent crystalline intermediates that precede the formation of amides. We applied our methodology for the quantitative synthesis of the active pharmaceutical ingredient moclobemide.

Diamondoid ether clusters in helium nanodroplets.

Diamondoid ethers were introduced into superfluid helium nanodroplets and the resulting clusters were analyzed by time-of-flight mass spectrometry. Clusters of higher abundances (magic number clusters) were identified and the corresponding potential cluster geometries were obtained from GFN2-xTB and DFT computations. We found that the studied diamondoid ethers readily self-assemble in helium nanodroplets and that London dispersion attraction between hydrocarbon subunits acts as a driving force for cluster formation.

Preparation and characterization of non-aromatic ether self-assemblies on a HOPG surface.

On-surface self-assemblies of aromatic organic molecules have been widely investigated, but the characterization of analogous self-assemblies consisting of fully sp-hybridized molecules remains challenging. The possible on-surface orientations of alkyl molecules not exclusively comprised of long alkyl chains are difficult to distinguish because of their inherently low symmetry and non-planar nature. Here, we present a detailed study of diamondoid ethers, structurally rigid and fully saturated molecules, which form uniform 2D monolayers on a highly oriented pyrolytic graphite (HOPG) surface.

London dispersion dominating diamantane packing in helium nanodroplets.

Diamantane clusters formed inside superfluid helium nanodroplets were analyzed by time-of-flight mass spectrometry. Distinct cluster sizes were identified as "magic numbers" and the corresponding feasible structures for clusters consisting of up to 19 diamantane molecules were derived from meta-dynamics simulations and subsequent DFT computations. The obtained interaction energies were attributed to London dispersion attraction.