Orbit Interaction Research Articles

Three-Dimensional Topological Semimetal/Insulator States in α-Type Organic Conductors with Interlayer Spin–Orbit Interaction

Three-Dimensional Topological Semimetal/Insulator States in <i>α</i>-Type Organic Conductors with Interlayer Spin–Orbit Interaction

Engineering the electron localization of metal sites on nanosheets assembled periodic macropores for CO2 photoreduction

Photocatalytic conversion of CO2 into syngas is highly appealing, yet still suffers from the undesirable product yield due to the sluggish carrier transfer and the uncontrollable affinity between catalytic sites and intermediates. Here we report the fabrication of Co sites with tunable electron localization capability on two dimensional (2D) nanosheets assembled three dimensional (3D) ordered macroporous framework (3DOM-NS). The as-prepared Co-based 3DOM-NS catalysts exhibit attractive photocatalytic performances toward CO2 reduction, among which the cobalt sulfide one (3DOM Co-SNS) shows the highest syngas generation rate up to 347.3 μmol h−1 under the irradiation of visible light and delivers a remarkable catalytic activity (1150.7 μmol h−1) in a flow reaction system under natural sunlight. Mechanism studies reveal that the high electron localization of metal sites in 3DOM Co-SNS strengthens the interaction between Co and HCOO* via the orbital interactions of dyz/dxz-p and s-s, thus facilitating the cleaving process of C-O bond. Additionally, the ordered macroporous framework with nanosheet subunits elevates the transfer efficiency of photoexcited electrons, which contributes to its high activity.

Computational Insights into the Effect of Ligands and Transition-Metal Centers on the Mechanism and Regioselectivity of Hydrosilylation of Alkenes.

Development of sustainable synthetic methods for the hydrosilylation of alkenes, catalyzed by 3d transition metals, offers a promising alternative to traditional noble metal catalysts. This study presents a computational mechanistic investigation into the hydrosilylation of alkenes, focusing on the role of ligands and metal centers in modulating the reaction's mechanism and regioselectivity. The ligand's electronic and steric properties were found to modulate the regioselectivity for cobalt catalysts, with phosphine ligand (xantphos) promoting higher linear selectivity compared to nitrogen-based ligand (mesPDI). The energy decomposition analysis reveals that the xantphos ligand favors linear products due to stronger electrostatic and orbital interactions despite increased steric repulsion. The metal center also plays a crucial role, with cobalt catalysts favoring the modified Chalk-Harrod mechanism for branched product formation in the presence of PNN ligand (iPrPCNNMe), due to lower activation barriers in alkene insertion. Beneficial electrostatic and orbital interactions predominate, rendering the alkene insertion transition state for cobalt more favorable compared to that for iron. This work provides a comprehensive understanding of how ligand and metal center effects can be harnessed to control regioselectivity in hydrosilylation reactions.

Effect of a single water molecule on the conformational preferences of a capped Pro–Gly dipeptide in the gas phase

Herein, we have investigated the effect of microhydration on the secondary structure of a capped dipeptide Boc-DPro-Gly-NHBn-OMe (Boc = tert-butyloxycarbonyl, Bn = Benzyl), i.e., Pro–Gly (PG) with a single H2O molecule using gas-phase laser spectroscopy combined with quantum chemistry calculations. Observation of a single conformer of the monohydrated peptide has been confirmed from IR-UV hole-burning spectroscopy. Both gas-phase experimental and theoretical IR spectroscopy results confirm that the H2O molecule is inserted selectively into the relatively weak C7 hydrogen bond (γ-turn) between the Pro C=O and NHBn N–H groups of the peptide, while the other C7 hydrogen bond (γ-turn) between the Gly N–H and Boc C=O groups remains unaffected. Hence, the single H2O molecule in the PG⋯(H2O)1 complex significantly distorts the peptide backbone without appreciable modification of the overall secondary structural motif (γ–γ) of the isolated PG monomer. The nature and strength of the intra- and inter-molecular hydrogen bonds present in the assigned conformer of the PG⋯(H2O)1 complex has also been examined by natural bond orbital and non-covalent interaction analyses. The present investigation on the monohydrated peptide demonstrates that several H2O molecules may be required for switching the secondary structure of PG from the double γ-turn to a β-turn that is favorable in the condensed phase.

4d Metal-doped liquid Ga for efficient ammonia electrosynthesis at wide N2 concentrations

Electrocatalytic nitrogen reduction reaction under ambient conditions is a promising pathway for ammonia synthesis. Currently nitrogen reduction reactions are carried out in N2-saturated environments and use high-purity nitrogen as feedstock, which is costly. Here, we prepared carbon-coated ultra-low 4d metal Ru-doped liquid metal Ga (Ru0.06/LM@C) for NRR over a wide range of N2 concentrations. Comprehensive analyses show that the introduction of the ultra-low 4d element Ru can effectively adjust the electronic structure through orbital interactions, thus enhancing the adsorption of nitrogen-containing intermediates. The liquid catalyst utilized its mobility to provide a higher density of active sites. In addition, the material Ru0.06/Ga@C itself has the ability to promote product desorption. The three act synergistically to optimize the N2 mass transfer path, thereby increasing the *NNH coverage and further improving the ammonia yield over a wide range of N2 concentrations. The maximum NH3 yield of the catalyst can reach 126.0 μg h−1 mgcat−1 (at –0.3 V vs. RHE) with high purity N2 as feed gas, and the Faraday efficiency is 60.4% at –0.1 V vs. RHE. Over a wide range of N2 concentrations, the NH3 yield of the catalyst was greater than 100 μg h−1 mgcat−1 with a Faraday efficiency higher than 47%. The catalytic performance is much higher than that of solid Ga@C and reported p-block metal-based catalysts.

Synthesis, structure, DFT study and molecular docking inspection of spirobi[hexahydropyrimidine]-diones derivative

It has been established that three-component condensation of benzaldehyde, acetone and urea catalyzed H2SO4 leads to the formation of spirobi[hexahidropyrimidine]-dione derivatives. The structure of the synthesized compound has been proved by X-ray method. The results of the quantum theory of atom-in-molecule and noncovalent interaction index analysis showed no intramolecular hydrogen bonds in the molecule studied. However, it contains four N-H bonds and two C=O groups. Based on the result of the DFT-NBO analysis, it was the lone pairs of oxygen on the C=O group which are forming strong orbital interactions with the antibonding orbital of the C-N single bond. The molecular docking was performed to investigate potential binding interactions of the compound with four target proteins including 5I4T (HIV-1), 5R7Z, 6M71 and 6VYB (SARS-Cov-2). Additionally, in-silico drug-likeness and ADME studies suggested oral activity (violations ≤ 1) of scaffold and predicted to be actively effluxed by P-gp (PGP+).

Intrinsic spin-orbit interaction in ferromagnet/superconductor hybrid nanostructures: Unveiling the role in triplet generation and critical temperature modulation

Recent theoretical advancements propose an innovative approach to induce triplet generation beyond the conventional inhomogeneous magnetic field-driven singlet-triplet conversion. Here, we investigate a hybrid nanostructure comprising a conventional BCS superconductor proximitized with a homogeneous ferromagnet possessing intrinsic spin–orbit coupling arising from broken symmetries due to lattice mismatch at the interface. Through extensive simulations, we explore the impact of spin–orbit interaction on the critical temperature, revealing the pivotal role played by the in-plane component of the magnetic exchange field and the dimensional characteristics of the hybrid system in singlet-triplet conversion. Remarkably, our findings demonstrate that a single homogeneous ferromagnet with intrinsic spin–orbit coupling governs triplet generation and exhibits a spin valve effect. Notably, we quantify our observations through the superconducting critical temperature (Tc), showcasing a spin-valve like functionality dependent on the orientation of magnetization. Moreover, we observe a significant reduction in the critical temperature of the hybrid structure, even reaching zero under specific dimensions, attributed to the controlled generation and regulation of spin-1 triplets. Crucially, our investigation also validates the notion of the mechanism where a π2 rotation of the in-plane magnetic exchange field toggles superconductivity, offering a promising avenue for actively controlling triplet generation—a pivotal step towards high-performance storage devices in emerging superconducting spintronics applications.

High-Throughput Search for Photostrictive Materials Based on a Thermodynamic Descriptor.

Photostriction is a phenomenon that can potentially improve the precision of light-driven actuation, the sensitivity of photodetection, and the efficiency of optical energy harvesting. However, known materials with significant photostriction are limited, and effective guidelines to discover new photostrictive materials are lacking. In this study, we perform a high-throughput computational search for new photostrictive materials based on simple thermodynamic descriptors, namely, the band gap pressure and stress coefficients. Using the Δ-SCF method based on density functional theory, we establish that these descriptors can accurately predict intrinsic photostriction in a wide range of materials. Subsequently, we screened over 4770 stable semiconductors with a band gap below 2 eV from the Materials Project database to search for strongly photostrictive materials. This search identifies Te2I as the most promising candidate, with photostriction along out-of-plane direction exceeding 8 × 10-5 with a moderate photocarrier concentration of 1018 cm-3. Furthermore, we provide a detailed analysis of factors contributing to strong photostriction, including bulk moduli and band-edge orbital interactions. Our results provide physical insights into the photostriction of materials and demonstrate the effectiveness of using simple descriptors in high-throughput searches for new functional materials.

Catalyst-free in-plane growth of high-quality ultra-thin InSb nanowires

InSb nanowires (NWs) show an important application in topological quantum computing owing to their high electron mobility, strong spin–orbit interaction, and large g factor. Particularly, ultra-thin InSb NWs are expected to be used to solve the problem of multiple sub-band occupation for the detection of Majorana fermions. However, it is still difficult to epitaxially grow ultra-thin InSb NWs due to the surfactant effect of Sb. Here, we develop an in-plane self-assembled technique to grow catalyst-free ultra-thin InSb NWs on Ge(001) substrates by molecular-beam epitaxy. It is found that ultra-thin InSb NWs with a diameter as small as 17 nm can be obtained by this growth manner. More importantly, these NWs have aspect ratios of 40–100. We also find that the in-plane InSb NWs always grow along the [110] and [11¯0] directions, and they have the same {111} facets, which are caused by the lowest-surface energy of {111} crystal planes for NWs grown with a high Sb/In ratio. Detailed structural studies confirm that InSb NWs are high-quality zinc blende crystals, and there is a strict epitaxial relationship between the InSb NW and the Ge substrate. The in-plane InSb NWs have a similar Raman spectral linewidth compared with that of the single-crystal InSb substrate, further confirming their high crystal quality. Our work provides useful insights into the controlled growth of in-plane catalyst-free III–V NWs.

Examining the reactivity of oxygen-bridged intramolecular group 13 element/phosphorus and boron/group 15 element frustrated Lewis pairs in 1,2-addition reactions with CS2.

The 1,2-addition reactions involving CS2 and oxygen-bridged intramolecular G13/P-based (G13 = group 13 element) and B/G15-based (G15 = group 15 element) frustrated Lewis pairs (FLPs) have been theoretically analyzed through density functional theory (DFT). Our DFT calculations suggest that of the nine FLP-assisted compounds, only B/P-Rea, Al/P-Rea, Ga/P-Rea, and In/P-Rea can kinetically and thermodynamically initiate energetically favorable 1,2-addition reactions with CS2, forming five-membered heterocyclic adducts. Our findings from the activation strain model suggest that the atomic radius of the Lewis acceptor (G13) and donor (G15) is critical in setting the barrier heights needed for optimal orbital interactions between G13/P-Rea, B/G15-Rea, and CS2. The EDA-NOCV (energy decomposition analysis-natural orbitals for chemical valence) analysis we conducted indicates that donor-acceptor bonding (singlet-singlet) plays a more dominant role than electron-sharing bonding (triplet-triplet) in the transition states G13/P-TS and B/G15-TS. Based on frontier molecular orbital theory and EDA-NOCV analyses, the bonding in the 1,2-addition reactions of oxygen-bridged intramolecular G13/P-Rea and B/G15-Rea with CS2 is primarily influenced by the forward interaction (lone pair (G15) → p-π*(CS2)), while the backward interaction (p-π*(G13) ← p-π(CS2)) has a relatively minor influence. Several significant findings derived from the current theoretical analyses are discussed in this work.

High-Entropy Metal Sulfide Promises High-Performance Carbon Dioxide Reduction.

The efficient conversion of carbon dioxide (CO2) requires the development of stable catalysts with high selectivity and reactivity within a wide potential range. Here, the high-entropy metal sulfide CuAgZnSnS4 is designed for CO2 reduction with excellent performance (FEcarbonproducts ≥ 90%) in whole test potential windows (600 mV) based on the synergistic effect of the high-entropy metal sulfide. In particular, CuAgZnSnS4 exhibits better single-product selectivity with the highest FEHCOOH/FECO value (29.03) at -1.28 versus reversible hydrogen electrode (RHE). In combination with in situ measurements and theoretical calculations, it is further revealed that the synergistic effect of CuAgZnSnS4 realizes the controllable regulation of the surface electronic structure at Sn active sites, strengthening orbital interactions between *OCHO and Sn active sites. As a result, the effective adsorption and activation of *OCHO instead of *H are obtained, improving the single-product selectivity of electrocatalytic CO2 reduction and inhibiting the competitive hydrogen evolution reaction significantly. Our findings may complete the understanding of the synergistic effect for high-entropy materials in catalysis and offer new insight into the design of efficient electrocatalysts with high catalytic activity.

Theoretical investigation of electric field influence on the decomposition species and reaction routes of C4F7N over Cu(111) surface

The use of eco-friendly insulation gas C4F7N as a replacement for the greenhouse gas SF6 is critical for achieving net-zero emissions. However, the discharge-induced decomposition mechanisms of C4F7N on electrode surfaces remain unclear, posing significant challenges to the development of new insulation equipment. In this study, we performed density functional theory (DFT) calculations to investigate the discharge-induced decomposition of C4F7N on the Cu(111) surface. The adsorption energy of decomposition intermediates is influenced by both the strength and polarity of the electric field (E-field) by altering surface charge transfer and orbital interactions. Negative E-fields enhance the adsorption stability, whereas positive E-fields destabilize it. Stable products, such as CF4, C2F6, C3F6, and C3F8, exhibit physical adsorption on Cu(111) and are insensitive to the E-field. The decomposition process of C4F7N follows multiple pathways when it transitions from C4 to C3 species, with the reaction energy closely related to the detachment and desorption of intermediates. A negative E-field reduces the reaction enthalpy and lowers the overall energy of the decomposition pathway, while a positive E-field facilitates the formation of stable CxFy products. This study offers insights into the decomposition mechanism of C4F7N in discharge, providing guidance for the development of new eco-friendly insulation equipment.

Interband optical absorption coefficient of the diluted magnetic semiconductor ellipsoid quantum dot with Rashba spin orbit interaction

Interband optical absorption coefficient of the diluted magnetic semiconductor ellipsoid quantum dot with Rashba spin orbit interaction

A Double-walled Noncovalent Carbon Nanotube by Columnar Packing of Nanotube Fragments.

Herein, we report the synthesis of double-walled noncovalent carbon nanotubes (CNTs) through host-guest complexation of nanotube fragments and tube-forming crystal engineering. As the smallest fragment of double-walled CNTs, a host-guest complex of perfluorocycloparaphenylene (PFCPP) and carbon nanobelt (CNB) was synthesized by mixing them in solvents. The immediate complexation of the PF[12]CPP⸧(6,6)CNB complex with a remarkably high association constant (Ka) of 2×105 L/mol was observed. Time-dependent 1H NMR and thermogravimetry measurements revealed that the stability of (6,6)CNB was significantly improved by encapsulation. X-ray crystallography confirmed the robust belt-in-ring structure of this complex. As indicated by the short distance between PF[12]CPP and (6,6)CNB (2.8 Å), intermolecular orbital interactions exist between the belt and the ring, which were further supported by theoretical calculation and phosphorescence quenching experiments. While the PF[12]CPP⸧(6,6)CNB complex adopts various crystal packing structures, chloroform was discovered to be a magic "glue" solvent inducing one-dimensional alignment of the PF[12]CPP⸧(6,6)CNB complex to build an unprecedented double-walled noncovalent CNT structure.

A Double‐walled Noncovalent Carbon Nanotube by Columnar Packing of Nanotube Fragments

AbstractHerein, we report the synthesis of double‐walled noncovalent carbon nanotubes (CNTs) through host–guest complexation of nanotube fragments and tube‐forming crystal engineering. As the smallest fragment of double‐walled CNTs, a host–guest complex of perfluorocycloparaphenylene (PFCPP) and carbon nanobelt (CNB) was synthesized by mixing them in solvents. The immediate complexation of the PF[12]CPP⸧(6,6)CNB complex with a remarkably high association constant (Ka) of 2×105 L/mol was observed. Time‐dependent 1H NMR and thermogravimetry measurements revealed that the stability of (6,6)CNB was significantly improved by encapsulation. X‐ray crystallography confirmed the robust belt‐in‐ring structure of this complex. As indicated by the short distance between PF[12]CPP and (6,6)CNB (2.8 Å), intermolecular orbital interactions exist between the belt and the ring, which were further supported by theoretical calculation and phosphorescence quenching experiments. While the PF[12]CPP⸧(6,6)CNB complex adopts various crystal packing structures, chloroform was discovered to be a magic “glue” solvent inducing one‐dimensional alignment of the PF[12]CPP⸧(6,6)CNB complex to build an unprecedented double‐walled noncovalent CNT structure.

Chirality-induced phonon spin selectivity by elastic spin–orbit interaction

Spin and orbital degrees of freedom are crucial in not only fundamental particles but also classical waves such as optical systems, wherein the spin-orbit interaction (SOI) of light provides new perspectives for manipulating electromagnetic waves. Elastic waves possess similar spin angular momentum (SAM) and orbital angular momentum (OAM). However, the elastic counterpart of SOI remains unexplored, even for ubiquitous elastic waveguides (WG). Here, we demonstrate the existence of elastic SOI in helical WG. We prove that the torsion and curvature of helical WG induces synthetic gauge potentials in describing the elastic vibrations. Through analytical theory and simulations, we unveil the interplay among elastic SAM, intrinsic OAM, and extrinsic OAM, impacted by the elastic SOI. Importantly, results show that elastic SOI can introduce the Chirality-Induced Phonon Spin Selectivity. These findings advance our understanding of angular momentum physics in elastic waves and enable practical strategies for wave manipulation.

Computational Studies of Molybdenum-Containing Metal–Sulfur and Metal–Hydride Clusters

The development of transition metal clusters is an active area of research in inorganic chemistry, as they can be used as catalysts to perform chemically or biologically relevant reactions. Computational chemistry, employing density functional theory (DFT), plays a key role in rationalizing the electronic structure and properties of transition metal clusters. This article reviews recent quantum chemical studies of Mo3S4M clusters (M = Fe, Co, Ni), their CO- or N2-bound variants, and metal–hydride clusters. The ground state of the cluster systems was computed, and properties such as metal–metal bonding, orbital interactions, fluxional behavior of ligands, spectroscopy, and reaction mechanisms were rationalized and compared with available experimental results. Our research findings evidence that computational studies employing quantum chemical methods can guide experimental researchers to develop novel transition metal clusters for potential applications in catalysis.

Lone Pair-π Interactions in Organic Reactions.

Noncovalent interactions between a lone pair of electrons and π systems can be categorized into two types based on the nature of π systems. Lone pair-π(C═O) interactions with π systems of unsaturated, polarized bonds are primarily attributed to orbital interactions, whereas lone pair-π(Ar) interactions with π systems of aromatic functional groups result from electrostatic attractions (for electron-deficient aryls) or dispersion attractions and Pauli repulsions (for electron-rich/neutral aryls). Unlike well-established noncovalent interactions, lone pair-π interactions have been comparatively underappreciated or less used to influence reaction outcomes. This review emphasizes experimental and computational studies aimed at integrating lone pair-π interactions into the design of catalytic systems and utilizing these interactions to regulate the reactivity and selectivity of chemical transformations. The role of lone pair-π interactions is highlighted in the stabilization or destabilization of transition states and ground-state binding. Examples influenced by lone pair-π interactions with both unsaturated, polarized bonds and aromatic rings as π systems are included. At variance with previous reviews, the present review is not structured according to the physical origin of particular classes of lone pair-π interactions but is divided into chapters according to ways in which lone pair-π interactions affect kinetics and/or selectivity of reactions.

Observation of acoustic hybrid topological phases induced by the p-d orbital interactions

Observation of acoustic hybrid topological phases induced by the p-d orbital interactions

Pd3 Sandwich Complexes with π-Cyclic Ligands: Theoretical Insight into Stability, Face-Capping Coordination Bond, Trans-Influence, and Backside-Ligand Effect.

Triangle Pd3 sandwich complexes with two face-capping π-cyclic ligands, [Pd3(Cm)(Cn)L3]2+ [L = acetonitrile; Cm, Cn = benzene, cycloheptatriene (CHT), cyclooctatetraene (COT), and [2.2]paracyclophane (PCP)], are theoretically investigated. The stability increases in the order [Pd3(C6H6)2L3]2+ ∼ [Pd3(C6H4Me2P)2L3]2+ (C6H4Me2P = p-xylene) < [Pd3(COT)2L3]2+ < [Pd3(CHT)2L3]2+ < [Pd3(PCP)2L3]2+ and [Pd3(C6H6)2L3]2+ ∼ [Pd3(C6H6)(C6H4Me2P)L3]2+ < [Pd3(C6H6)(PCP)L3]2+ < [Pd3(C6H6)(CHT)L3]2+ < [Pd3(C6H6)(COT)L3]2+ < [Pd3(CHT)(PCP)L3]2+ < [Pd3(COT)(PCP)L3]2+, where "bold" represents an experimentally isolated complex. Based on these results, we succeeded in synthesizing a new complex [Pd3(CHT)(PCP)L3]2+. Geometrical features suggest that benzene and PCP interact with one Pd atom using one C═C double bond and with two other Pd atoms using the other C═C double bond in the bridging manner. CHT interacts with three Pd atoms using three C═C double bonds. COT interacts with three Pd atoms using three C═C double bonds in [Pd3(COT)2L3]2+ and using π-allyl type MOs with additional participation of two C═C π bonds in [Pd3(C6H6)(COT)L3]2+. CHT and PCP weaken the benzene coordination bond in [Pd3(C6H6)(CHT)L3]2+ and [Pd3(C6H6)(PCP)L3]2+ like trans-influence. Unprecedentedly, COT strengthens the benzene coordination bond in [Pd3(C6H6)(COT)L3]2+. This "backside-ligand effect" arises from the characteristic coordination bond of the COT, which is elucidated based on the orbital interaction between the COT and Pd3 triangle.