Fabian Steudel

A shelf-stable and easy-to-prepare disulfurating reagent with chemoselectively displaceable amino and imide leaving groups is described. Protonation of this reagent promotes exclusive displacement of the amino group with various neutral carbon nucleophiles. The resulting dithiophthalimides are amenable to diverse substitution reactions under basic or neutral conditions, thus enabling expedient access to structurally diverse unsymmetrical disulfides.

Abstract

Synthetic methods for unsymmetrical disulfides are greatly needed owing to their applications in drug discovery, linker chemistry, and materials sciences. In this study, a new shelf-stable and easy-to-prepare bilateral disulfurating platform molecule, N-(morpholine-4-dithio)phthalimide, has been developed for the divergent synthesis of unsymmetrical disulfides. The amino and imide leaving groups of this reagent can be orthogonally transformed. Under acidic conditions, the amino moiety undergoes selective protonation and thus can be displaced by various carbon nucleophiles, such as allyl trimethylsilanes, alkynyl silanes, and electron-rich arenes, leaving the phthalimide moiety untouched. Meanwhile, the phthalimide leaving group is amenable to substitution under basic or neutral conditions. The combination of these transformations provides rapid access to diverse unsymmetrical disulfides through two C−S bond-forming reactions.

Nature Nanotechnology, Published online: 03 November 2022; doi:10.1038/s41565-022-01234-w

Homochiral helical toroids with micrometre-scale lengths are successfully fabricated by a combined solution–interface-directed hierarchical self-assembly strategy.

Dynamic covalent basket cages can now be made to exist for a tunable period of time as a function of the chemical fuel used to drive their formation. The stage is thus set to explore the functional characteristics of these fascinating molecules and mimic the action of natural systems capable of directing folding, catalysis, and transport in a spatiotemporal manner.

Abstract

Living systems use chemical fuels to transiently assemble functional structures. As a step toward constructing abiotic mimics of such structures, we herein describe dissipative formation of covalent basket cage CBC 5 by reversible imine condensation of cup-shaped aldehyde 2 (i.e., basket) with trivalent aromatic amine 4. This nanosized [4+4] cage (V=5 nm³, M _w=6150 Da) has shape of a truncated tetrahedron with four baskets at its vertices and four aromatic amines forming the faces. Importantly, tris-aldehyde basket 2 and aliphatic tris-amine 7 undergo condensation to give small [1+1] cage 6. The imine metathesis of 6 and aromatic tris-amine 4 into CBC 5 was optimized to bias the equilibrium favouring 6. Addition of tribromoacetic acid (TBA) as a chemical fuel perturbs this equilibrium to result in the transient formation of CBC 5, with subsequent consumption of TBA via decarboxylation driving the system back to the starting state.

Porphyrin nanoring template complexes provide a wealth of experimental NMR spectroscopy data, which are sensitive to global ring currents and which can be used to answer this question. Both experiment and theory confirm that nanoring cations are globally (anti)aromatic based on magnetic shielding evidence, and consistent with Hückel's rule.

Abstract

A recent Research Article in this journal by Matito and co-workers claimed that none of the oxidation states of a butadiyne-linked six-porphyrin nanoring exhibit global aromaticity or antiaromaticity. Here we show that this conclusion is incorrect. Experimental data from NMR spectroscopy for a whole family of nanorings provide strong evidence for global ring currents. The NMR data reveal these ring currents directly, without needing analysis by density functional theory (DFT). Furthermore, DFT calculations reproduce the experimental results when a suitable functional is used.

Nature Nanotechnology, Published online: 23 December 2021; doi:10.1038/s41565-021-01036-6

Beta-alumina solid electrolyte enhanced by yttria-stabilized zirconia can provide a very low interfacial impedance with a sodium metal anode and a critical current density higher than those previously reported in lithium and sodium batteries.

Nature Nanotechnology, Published online: 02 September 2021; doi:10.1038/s41565-021-00959-4

Although conventional analytical techniques can measure ensemble averages, single-molecule junctions can sense molecular reaction processes at the single-event level. The integration of a single-molecule Pd catalyst into a gapped graphene junction enables the electrical detection of a full catalytic cycle of the Suzuki–Miyaura coupling and clarifies the controversial transmetallation mechanism.