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Metal-metal contacts, though not yet widely realized, may provide exciting opportunities to serve as tunable and functional interfaces in single-molecule devices. One of the simplest components which might facilitate such binding interactions is the ferrocene group. Notably, direct bonds between the ferrocene iron center and metals such as Pd or Co have been demonstrated in molecular complexes comprising coordinating ligands attached to the cyclopentadienyl rings. Here, we demonstrate that ferrocene-based single-molecule devices with Fe-Au interfacial contact geometries form at room temperature in the absence of supporting coordinating ligands. Applying a photoredox reaction, we propose that ferrocene only functions effectively as a contact group when oxidized, binding to gold through a formal Fe³⁺center. This observation is further supported by a series of control measurements and density functional theory calculations. Our findings extend the scope of junction contact chemistries beyond those involving main group elements, lay the foundation for light switchable ferrocene-based single-molecule devices, and highlight new potential mechanistic function(s) of unsubstituted ferrocenium groups in synthetic processes.

 

Since their first observation in 2017, atomically thin van der Waals (vdW) magnets have attracted significant fundamental, and application-driven attention. However, their low ordering temperatures,T_c, sensitivity to atmospheric conditions and difficulties in preparing clean large-area samples still present major limitations to further progress, especially amongst van der Waals magnetic semiconductors. The remarkably stable, high-T_cvdW magnet CrSBr has the potential to overcome these key shortcomings, but its nanoscale properties and rich magnetic phase diagram remain poorly understood. Here we use single spin magnetometry to quantitatively characterise saturation magnetization, magnetic anisotropy constants, and magnetic phase transitions in few-layer CrSBr by direct magnetic imaging. We show pristine magnetic phases, devoid of defects on micron length-scales, and demonstrate remarkable air-stability down the monolayer limit. We furthermore address the spin-flip transition in bilayer CrSBr by imaging the phase-coexistence of regions of antiferromagnetically (AFM) ordered and fully aligned spins. Our work will enable the engineering of exotic electronic and magnetic phases in CrSBr and the realization of novel nanomagnetic devices based on this highly promising vdW magnet.

 

Pseudocapacitors offer a unique strategy to combine the rapid charging rates of capacitors with the high energy density of batteries, potentially offering a unique solution to energy storage challenges. Bending and twisting aromatic building blocks to form contorted aromatics have emerged as a new strategy to create organic materials with unique and tunable properties. This paper studies the union between these two concepts: molecular contortion and organic pseudocapacitors. The recent development of fully organic pseudocapacitors, including high-performing devices based on perylene diimide organic redox units, introduces the added benefit of low cost, synthetic tunability, and increased flexibility. We synthesize a series of polymers by joining perylene diimide with various linkers that incorporate a helical moiety from [4]helicene to [6]helicene into the molecular backbone. We prepare three new electroactive polymers that incorporate benzene, naphthalene, and anthracene linkers and study their pseudocapacitive performance to infer key design principles for organic pseudocapacitors. Our results show that the naphthalene linker results in the most strongly coupled redox centers and displays the highest pseudocapacitance of 292 ± 47 F/g at 0.5 A/g. To understand the pseudocapacitive behavior, we synthesized dimer model compounds to further probe the electronic structure of these materials through electronic absorption spectroscopy and first-principles calculations. Our results suggest that the identity of the aromatic linker influences the contortion between neighboring perylene diimide units, the coupling between redox centers, and their relative angles and distances. We find that competing molecular design factors must be carefully optimized to generate high-performance devices. Overall, this study provides key insights into molecular design strategies for generating high-performing organic pseudocapacitor materials. 

Molecular clusters can function as nanoscale atoms/superatoms, assembling into superatomic solids, a new class of solid‐state materials with designable properties through modifications on superatoms. To explore possibilities on diversifying building blocks, here we thoroughly studied one representative superatom, Co₆Se₈(PEt₃)₆. We probed its structural, electronic, and magnetic properties and revealed its detailed electronic structure as valence electrons delocalize over inorganic [Co₆Se₈] core while ligands function as an insulated shell.⁵⁹Co SSNMR measurements on the core and³¹P,¹³C on the ligands show that the neutral Co₆Se₈(PEt₃)₆is diamagnetic and symmetric, with all ligands magnetically equivalent. Quantum computations cross‐validate NMR results and reveal degenerate delocalized HOMO orbitals, indicating aromaticity. Ligand substitution keeps the inorganic core nearly intact. After losing one electron, the unpaired electron in [Co₆Se₈(PEt₃)₆]⁺¹is delocalized, causing paramagnetism and a delocalized electron spin. Notably, this feature of electron/spin delocalization over a large cluster is attractive for special single‐electron devices.

 

The transport of energy and information in semiconductors is limited by scattering between electronic carriers and lattice phonons, resulting in diffusive and lossy transport that curtails all semiconductor technologies. Using Re₆Se₈Cl₂, a van der Waals (vdW) superatomic semiconductor, we demonstrate the formation of acoustic exciton-polarons, an electronic quasiparticle shielded from phonon scattering. We directly imaged polaron transport in Re₆Se₈Cl₂at room temperature, revealing quasi-ballistic, wavelike propagation sustained for a nanosecond and several micrometers. Shielded polaron transport leads to electronic energy propagation lengths orders of magnitude greater than in other vdW semiconductors, exceeding even silicon over a nanosecond. We propose that, counterintuitively, quasi-flat electronic bands and strong exciton–acoustic phonon coupling are together responsible for the transport properties of Re₆Se₈Cl₂, establishing a path to ballistic room-temperature semiconductors.