Regulation of Reaction Pathways in Coordinated Chains by Directional Mechanical Force.

Mechanochemistry refers to chemical reactions induced by mechanical forces. Due to different reaction mechanisms, products obtained through mechanochemistry can be distinct from those produced by thermochemistry and photochemistry. Scanning probe microscopy is a powerful tool for studying single-molecule mechanochemical processes.

Chirality induced spin selectivity in electron transport investigated by scanning probe microscopy.

Chirality induced spin selectivity (CISS) effect implies the relationship between chirality and magnetism, attracting extensive attention in the fields of physics, chemistry and biology. Since it was first discovered with photoemission method in 1999, the CISS effect has been investigated and measured by a variety of methods. Among different means of measurements, scanning probe microscopy (SPM) as a powerful tool to explore the CISS effect, can directly measure and present the spin filtering property of chiral molecules in electron transport.

Conformational Control of σ-Interference Effects in the Conductance of Permethylated Oligosilanes.

As silicon-based integrated circuits continue to shrink, their molecular characteristics become more pronounced. However, the structure-property relationship of silicon-based molecular junctions remains to be elucidated. Here, an intuitive explanation of the effects of backbone dihedral angles on transport properties in permethylated oligosilanes is presented employing the Ladder C model Hamiltonian combined with nonequilibrium Green's function formalism.

Exploring Aromaticity Effects on Electronic Transport in Cyclo[n]carbon Single-Molecule Junctions.

Cyclo[n]carbon (C) is one member of the all-carbon allotrope family with potential applications in next-generation electronic devices. By employing first-principles quantum transport calculations, we have investigated the electronic transport properties of single-molecule junctions of C, with n = 14, 16, 18, and 20, connected to two bulk gold electrodes, uncovering notable distinctions arising from the varying aromaticities. For the doubly aromatic C and C molecules, slightly deformed complexes at the singlet state arise after bonding with one Au atom at each side; in contrast, the reduced energy gaps between the highest occupied and the lowest unoccupied molecular orbitals due to the orbital reordering observed in the doubly anti-aromatic C and C molecules lead to heavily deformed asymmetric complexes at the triplet state.

The Growth and Shape Evolution of Indium Nanoplates Studied by In Situ Liquid Cell TEM.

Understanding the growth mechanisms of nanomaterials is crucial for effectively controlling their morphology which may affect their properties. Here, the growth process of indium nanoplates is studied using in situ liquid cell transmission electron microscopy. Quantitative analysis shows that the growth of indium nanoplate is limited by surface reaction.

Tuning Surface Organic Structures by Small Gas Molecules through Catassembly and Coassembly.

The field of molecular assembly has seen remarkable advancements across various domains, such as materials science, nanotechnology, and biomedicine. Small gas molecules serve as pivotal modulators, capable of altering the architecture of assemblies via tuning a spectrum of intermolecular forces including hydrogen bonding, dipole-dipole interactions, and metal coordination. Surface techniques, notably scanning tunneling microscopy and atomic force microscopy, have proven instrumental in dissecting the structural metamorphosis and characteristic features of these assemblies at an unparalleled single-molecule resolution.

Effectively Enhancing the Conductance of Asymmetric Molecular Wires by Aligning the Energy Level and Symmetrizing the Coupling.

An asymmetric structure is an important strategy for designing highly conductive molecular wires for a gap-fixed molecular circuit. As the conductance enhancement in the current strategy is still limited to about 2 times, we inserted a methylene group as a spacer in a conjugated structure to modulate the structural symmetry. We found that the conductance drastically enhanced in the asymmetric molecular wire to 1.

Unzipping Carbon Nanotubes to Sub-5-nm Graphene Nanoribbons on Cu(111) by Surface Catalysis.

Graphene nanoribbons (GNRs) are promising in nanoelectronics for their quasi-1D structures with tunable bandgaps. The methods for controllable fabrication of high-quality GNRs are still limited. Here a way to generate sub-5-nm GNRs by annealing single-walled carbon nanotubes (SWCNTs) on Cu(111) is demonstrated.

Structure transformation from Sierpiński triangles to chains assisted by gas molecules.

Reversible transformations between fractals and periodic structures are of fundamental importance for understanding the formation mechanism of fractals. Currently, it is still a challenge to controllably achieve such a transformation. We investigate the effect of CO and CO molecules on Sierpiński triangles (STs) assembled from Fe atoms and 4,4″-dicyano-1,1':3',1″-terphenyl (C3PC) molecules on Au surfaces.

Robust covalent pyrazine anchors forming highly conductive and polarity-tunable molecular junctions with carbon electrodes.

In molecular electronics, electrode-molecule anchoring strategies play a crucial role in the design of stable and high-performance functional single-molecule devices. Herein, we employ aromatic pyrazine as anchors to connect a central anthracene molecule to carbon electrodes including graphene and armchair single-walled carbon nanotubes (SWCNTs), and theoretically investigate their atomic structures and electronic transport properties. These molecular junctions can be constructed condensation reactions of the central molecules terminated with -phenylenediamines with -quinone-functionalized nanogaps of graphene and SWCNT electrodes.

Observation of Biradical Spin Coupling through Hydrogen Bonds.

Investigation of intermolecular electron spin interaction is of fundamental importance in both science and technology. Here, radical pairs of all-trans retinoic acid molecules on Au(111) are created using an ultralow temperature scanning tunneling microscope. Antiferromagnetic coupling between two radicals is identified by magnetic-field-dependent spectroscopy.

Evaluation of toxicological safety and quality control of Luobufukebiri pill.

Ethnopharmacological Relevance: The Luobufukebiri pill is one of the characteristic medicines of Uygur nationality in Xinjiang. It has the effect of warming and tonifying the brain and kidney, benefiting the heart and filling the essential functions, mainly used to treat impotence, depression, spermatorrhea, premature ejaculation, bodily weakness, emaciation, and neurasthenia.

Aim Of The Study: This study evaluated the toxicology and developed a quality control protocol of Luobufukebiri pill to ensure its safety and effectiveness in clinical applications.

In Situ Tuning of the Charge-Carrier Polarity in Imidazole-Linked Single-Molecule Junctions.

Manipulating the nature of the charge carriers at the single-molecule level is one of the major challenges of molecular electronics. Using first-principles quantum transport calculations, we have investigated the electronic transport properties of imidazole-linked single-molecule junctions and identified the hydrogen atom bonded to the pyrrole-like nitrogen in imidazole as a switch to tune the polarity of the charge carriers. Our calculations show that the chemical nature of the imidazole anchors is dramatically altered by dehydrogenation, which changes the dominant charge carriers from electrons to holes.

Improving the short-term frequency stability of a magnetic-state-selected cesium beam clock with optical detection.

The microwave spectrum line shape and the signal-to-noise ratio of a compact optically detected magnetic-state-selection cesium beam clock are analyzed in this paper. As the noise analysis shows, the performance is related to the atomic utilization ratio and locking parameters when the laser frequency noise is the dominant noise source. Methods are adopted for realizing better short-term frequency stability of the clock, including using a highly efficient state-selection cesium beam tube, optimizing the locking parameters, and stabilizing the microwave power to maximize the error signal.

Using Weakly Supervised Deep Learning to Classify and Segment Single-Molecule Break-Junction Conductance Traces.

In order to design molecular electronic devices with high performance and stability, it is crucial to understand their structure-to-property relationships. Single-molecule break junction measurements yield a large number of conductance-distance traces, which are inherently highly stochastic. Here we propose a weakly supervised deep learning algorithm to classify and segment these conductance traces, a method that is mainly based on transfer learning with the pretrain-finetune technique.

On-surface preparation of coordinated lanthanide-transition-metal clusters.

The study of lanthanide (Ln)-transition-metal (TM) heterometallic clusters which play key roles in various high-tech applications is a rapid growing field of research. Despite the achievement of numerous Ln-TM cluster compounds comprising one Ln atom, the synthesis of Ln-TM clusters containing multiple Ln atoms remains challenging. Here, we present the preparation and self-assembly of a series of Au-bridged heterometallic clusters containing multiple cerium (Ce) atoms via on-surface coordination.

Surface self-assembly involving the interaction between S and N atoms.

Controllable molecular self-assembly is vital for nanostructure construction. Here, three different self-assembling networks are realized by varying the chemical composition of the molecular building blocks of the same architecture. This is the first time that SN electrostatic attraction has been employed to regulate surface self-assembly.

Manipulation of Molecular Spin State on Surfaces Studied by Scanning Tunneling Microscopy.

The adsorbed magnetic molecules with tunable spin states have drawn wide attention for their immense potential in the emerging fields of molecular spintronics and quantum computing. One of the key issues toward their application is the efficient controlling of their spin state. This review briefly summarizes the recent progress in the field of molecular spin state manipulation on surfaces.

Packing Sierpiński Triangles into Two-Dimensional Crystals.

Fractals are of fundamental importance in science and technology. Theoretical simulations indicate that Sierpiński triangles (STs) possess specific optical and electronic properties. To study their properties and uncover their potential applications, it is necessary to pack STs into large-scale two-dimensional crystalline structures.

Single-Molecule Conductance through an Isoelectronic B-N Substituted Phenanthrene Junction.

Single-molecule conductance of a B-N substituted phenanthrene derivative and its isoelectronic C═C counterpart was investigated by the scanning tunneling microscopy break junction (STM-BJ) technique. The incorporation of the B-N motif results in a better single-molecule conductivity than the C═C analogue. Furthermore, the Lewis acid-base reaction between F and the B atom of the B-N motif leads to a decrease of the conductance of the BN derivative, which can be understood due to the shifting of the energy positions of the LUMO, as revealed by quantum transport calculations, even though the HOMO-LUMO gap decreases in the B-F Lewis acid-base.

Tuning rotation axes of single molecular rotors by a combination of single-atom manipulation and single-molecule chemistry.

Defining the axis of a molecular rotation is vital for the bottom-up design of molecular rotors. The rotation of tin-phthalocyanine molecules on the Ag(111) surface is studied by scanning tunneling microscopy and atomic/molecular manipulation at 4 K. Tin-phthalocyanine acts as a molecular rotor that binds to Ag adatoms and the substrate.

Construction and Properties of Sierpiński Triangular Fractals on Surfaces.

Fractal structures are of fundamental importance in science, engineering, mathematics, and aesthetics. Construction of molecular fractals on surfaces can help to understand the formation mechanism of fractals and a series of achievements have been acquired in the preparation of molecular fractals. This review focuses on Sierpiński triangles (STs), representatives of various prototypical fractals, on surfaces.

A two-dimensional crystal formed by pentamers on Au(111).

A new type of two-dimensional crystal comprising supramolecular pentamers on Au(111) is studied using an ultra-high vacuum low-temperature scanning tunnelling microscope. (2E,4E)-3-Methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienoic acid molecules form pentamers through five-fold OH-O hydrogen bonds. In ordered arrays, pentamers interact with each other via van der Waals interactions.