Towards Responsive Single‐Molecule Device

Molecular magnetoresistance enhanced by destructive quantum interference of a [π⋯π] supramolecule

Molecular magnetoresistance shows promise for future computer memory and storage technology applications. In this study, we design a novel molecular device to achieve this magnetoresistance, where a [π⋯π] supramolecule composed of two DCV4T (dicyanovinyl end-capped quaterthiophene) monomers is employed as the functional unit, and sandwiched between two ferromagnetic electrodes. Density functional theory investigations reveal that the magnetoresistance ratio (MR) is influenced by the configuration of the supramolecule and the temperature. Remarkably, the maximum MR of the designed device can reach up to 18 000% even at room temperature. This exceptional magnetoresistance is basically associated with the destructive quantum interference (DQI) between electron transmissions through the highest-occupied and lowest-unoccupied molecular orbitals of the [π⋯π] supramolecule, occurring near the Fermi level of the device. Our study paves the way for significant enhancement of molecular magnetoresistance grounded in the DQI effect, especially through the use of [π⋯π] supramolecules.

Single-Molecule Conductance of Neutral Closed-Shell and Open-Shell Diradical Indenofluorenes

Organic diradicals are highly promising candidates as future components in molecular electronic and spintronic devices because of their low spin-orbit coupling. To advance toward final circuit realizations, a thorough knowledge of the behavior of diradicals within a single-molecule junction framework is imperative. In this work, we have measured for the first time the single-molecule conductance of a neutral open-shell diradical compound, a [2,1-b] isomer of indenofluorene (IF). Our results reveal that the conductance of the [2,1-b] isomer is about 1 order of magnitude higher than that of the corresponding closed-shell regioisomer [1,2-b] IF. This is significant, as it fundamentally demonstrates the possibility of forming stable single-molecule junctions using neutral diradical compounds which are also highly conducting. This opens up a new approach to the development of externally addressable spintronic devices operable at room temperature.

The Rise of 1,4-BN-Heteroarenes: Synthesis, Properties, and Applications

BN-heteroarenes, which employ both boron and nitrogen in aromatic hydrocarbons, have gained great attention in the fields of organic chemistry and materials science. Nevertheless, the extensive studies on BN-heteroarenes are largely limited to 1,2-azaborine-based compounds with B-N covalent bonds, whereas 1,3- and 1,4-BN-heteroarenes are relatively rare due to their greater challenge in the synthesis. Recently, significant progresses have been achieved in the synthesis and applications of BN-heteroarenes featuring 1,4-azaborines, especially driven by their significant potential as multiresonant thermally activated delayed fluorescence (MR-TADF) materials. Therefore, it is timely to review these advances from the chemistry perspective. This review summarizes the synthetic methods and recent achievements of 1,4-azaborine-based BN-heteroarenes and discusses their unique properties and potential applications of this emerging class of materials, highlighting the value of 1,4-BN-heteroarenes beyond MR-TADF materials. It is hoped that this review would stimulate the conversation and cooperation between chemists who are interested in azaborine chemistry and materials scientists working in the fields of organic optoelectronics, metal catalysis, and carbon-based nanoscience etc.