An interface between a metallic cluster (MgAl12) and a semiconducting cluster (Re6Se8(PMe3)5) is shown to be marked by a massive dipole reminiscent of a dipolar layer leading to a Schottky barrier at metal-semiconductor interfaces. The metallic cluster MgAl12 with a valence electron count of 38 electrons is two electrons short of 40 electrons needed to complete its electronic shells in a superatomic model and is marked by a significant electron affinity of 2.99 eV. On the other hand, the metal-chalcogenide semiconducting cluster Re6Se8(PMe3)5, consisting of a Re6Se8 core ligated with five trimethylphosphine ligands, is highly stable in the +2 charge-state owing to its electronic shell closure, and has a low ionization energy of 3.3 eV. The composite cluster Re6Se8(PMe3)5-MgAl12 formed by combining the MgAl12 cluster through the unligated site of Re6Se8(PMe3)5 exhibits a massive dipole moment of 28.38 D resulting from a charge flow from Re6Se8(PMe3)5 to the MgAl12 cluster. The highest occupied molecular orbital (HOMO) of the composite cluster is on the MgAl12 side, which is 0.53 eV below the lowest unoccupied molecular orbital (LUMO) localized on the Re6Se8(PMe3)5 cluster, reminiscent of a Schottky barrier at metal-semiconductor interfaces. https://www.selleckchem.com/products/cirtuvivint.html Therefore, the combination can act as a rectifier, and an application of a voltage of approximately 4.1 V via a homogeneous external electric field is needed to overcome the barrier aligning the two states the HOMO in MgAl12 with the LUMO in Re6Se8(PMe3)5. Apart from the bias voltage, the barrier can also be reduced by attaching ligands to the metallic cluster, which provides chemical control over rectification. Finally, the fused cluster is shown to be capable of separating electron-hole pairs with minimal recombination, offering the potential for photovoltaic applications.Seven partially and fully fluorinated/chlorinated pyridines were investigated by means of FT-IR and Raman spectroscopy combined with quantum chemical calculations, mainly aiming to detect how the nature and position of F and Cl substituents affect the in-plane ring normal modes (RNMs) of pyridines in terms of vibrational wavenumbers, force constants, IR intensities and Raman activities. Taking pyridine as the reference, the RNMs and some derived RNMs through coupling with related C-X (X = F, Cl) stretching vibrations were identified on the basis of their composition in terms of internal coordinates. The impact of fluorination and chlorination on these RNMs was also discussed from the perspective of frontier molecular orbitals (MOs), maps of the molecular electrostatic potential (MEP) and the molecular topology. Natural bond orbital (NBO) analysis revealed the consequences of substitutions on the intramolecular charge delocalisation and consequently the ring bond strength. Moreover, the effects of anharmonicity of the potential on vibrational frequencies were presented and discussed.Semiconducting two-dimensional Janus materials have drawn increasing attention due to their novel optoelectronic properties. Here, employing first-principles calculations, we systematically explore the stability and electronic and optical properties of Janus diamane C4FCl. The energetic and dynamical stabilities of C4FCl have been verified using the cohesive energy and phonon dispersion calculations. It is predicted to possess a direct bandgap of ∼3 eV at the Γ point using the G0W0 method. Also, the optical absorption spectrum of C4FCl is dominated by the enhanced excitonic effects, in which a bright bound exciton with a large binding energy beyond 1 eV can be observed. The light absorption coefficient of C4FCl for sunlight can be as large as 8 × 104 cm-1 in the range of visible and near-ultraviolet light, suggesting its potential for optoelectronic applications. These findings enable a deep understanding of the physical properties of novel C4FCl.The origin of enantioselectivity in asymmetric catalysis is often built around the differential steric interaction in the enantiocontrolling transition states (TSs). A closer perusal of enantiocontrolling TSs in an increasingly diverse range of reactions has revealed that the cumulative effect of weak noncovalent interactions could even outweigh the steric effects. While enunciating this balance is conspicuously important, quantification of such intramolecular forces within a TS continues to remain scarce and challenging. Herein, we demonstrate the utility of the fragment molecular orbital method in establishing the relative contributions of various attractive and repulsive contributions in the total interaction energy between the suitably chosen fragments in enantiocontrolling TSs. Three types of reactions of high contemporary importance, namely, axially chiral phosphoric acid (CPA) catalyzed kinetic resolution of rac-α-methyl-γ-hydroxy ester (reaction I), asymmetric dearomative amination of β-naphthols by de interactions. These quantitative insights on the intramolecular interactions in the stereocontrolling TSs could help in the rational design of asymmetric catalysis.Zinc(ii) tetraphenylporphyrin (ZnTPP) has very broad application prospects in the fields of supramolecular chemistry, solar cells and nanomaterials. In this paper, by using scanning tunneling microscopy (STM), we systematically investigated the ZnTPP molecule and its four derivatives formed by thermal annealing were characterized unambiguously by bond-resolved STM (BR-STM). The electronic properties of the ZnTPP molecule and its four cyclodehydrogenation products were investigated by scanning tunneling spectroscopy (STS) combined with DFT calculations. The spatial distribution of molecular frontier orbitals of four products was obtained by dI/dV mappings. This work gives rise to a full-scale investigation of ZnTPP on Au(111), which will be potentially useful in nanodevices and optoelectronics.The relationship between the adsorption of water on MIL-53 (Al) MOF, the structural phase of MIL-53 (Al), and the quadrupole coupling constant of 27Al framework aluminium atom (QCC) of the MOF AlO4(OH)2 centres (Al-sites) has been investigated by combining solid-state 27Al MAS NMR spectroscopy with XRD analysis and DFT calculations. It is established that 27Al QCC is primarily sensitive to water adsorption to the Al-sites and by a minor extent to the framework contraction/expansion interconversions. We thus conclude that the 27Al MAS NMR method is sensitive enough to differentiate the effects of pore contractions and water adsorption to Al-sites basing on the changes of the QCC value.Two-dimensional (2D) materials with outstanding electronic and mechanical properties have attracted considerable attention as efficient thermoelectric materials. Here, we propose a generalized eight-valence electron rule for designing 2D semiconductor materials, i.e., metal-shrouded bimetallic phosphides ABP (A group IA element, B group IIA element). Following this rule, we screen out ten stable semiconductors (LiMgP, LiCaP, LiSrP, NaBeP, NaMgP, KMgP, KCaP, RbMgP, RbCaP and RbSrP) with tunable bandgaps in the range of 0.35-2.40 eV by comprehensive first-principles calculations. Among them, the electron mobility of RbMgP can be as high as 2.3 × 104 cm2 V-1 s-1, and the hole mobility of KMgP is estimated to be 9.9 × 103 cm2 V-1 s-1. Moreover, KMgP, KCaP, RbCaP and RbSrP exhibit an ultralow thermal conductivity of 0.02, 0.14, 0.08 and 0.14 W m-1 K-1, respectively. As a result, KMgP and RbCaP monolayers are p-type or n-type thermoelectric materials with a figure of merit of 2.25 and 1.13 at room temperature, respectively. The underlying mechanism of high electron conductivity and low thermal conductivity has been correlated with their unique bonding characteristics, narrow phonon band gap and the scattering from low-frequency phonons. This work demonstrates not only a guiding electron principle to design stable 2D semiconductors, but also a powerful metal-shrouded strategy for discovering high performance thermoelectric materials by decoupling electronic and thermal transport properties.Converting earth-abundant nitrogen (N2) gas into ammonia (NH3) under mild conditions is one of the most important issues and a long-standing challenge in chemistry. Herein, a new superatom Ca3B was theoretically designed and characterized to reveal its catalytic performance in converting N2 into NH3 by means of density functional theory (DFT) computations. The alkali-metal-like identity of this cluster is verified by its lower vertical ionization energy (VIE, 4.29 eV) than that of potassium (4.34 eV), while its high stability was guaranteed by the large HOMO-LUMO gap and binding energy per atom (Eb). More importantly, this well-designed superatom possesses unique geometric and electronic features, which can fully activate N2via a "double-electron transfer" mechanism, and then convert the activated N2 into NH3 through a distal reaction pathway with a small energy barrier of 0.71 eV. It is optimistically hoped that this work could intrigue more endeavors to design specific superatoms as excellent catalysts for the chemical adsorption and reduction of N2 to NH3.Calcite (CaCO3, space group R3[combining macron]c) is a solid phase whose well-known highly anisotropic physical properties can be exploited to compare and calibrate various theoretical simulation methods. In this work, to benchmark different ab initio Density Functional Theory approaches that include for the first time corrections for dispersive forces, a systematic analysis of structural, electronic, dielectric, optical and vibrational properties of calcite is performed. The simulations considered the generalized-gradient approximation functional PBE and the hybrid B3LYP and PBE0, whereas the DFT-D2 and DFT-D3 schemes were adopted to account for the long-range interactions. This study suggests an overall better agreement between the theoretical results obtained with the DFT functionals corrected for the dispersive forces, with a better performance of hybrid functionals over PBE.This study designs a carbon nanotube (CNT)-based rotary nanomotor actuated by four graphene origami (G-ori) drivers with adjustable positions. When the drivers' tips have different contact states with the CNT rotor at a finite temperature, the rotor has different rotational states due to different interaction strength between the rotor and the tips. Using the molecular dynamics simulation approach, we study the effects of the drivers' position, such as the gaps between the rotor and the drivers' tips and their layout angles. Numerical results indicate that both the stable rotational frequency (SRF) and the rotational direction change with the layout angles. In an interval from -40° to -25°, the SRF increases monotonously. There also exists an angle interval in which the G-ori drivers fail to actuate the rotor's rotation. The gap offset leads to different SRF of the same rotor. Hence, one can design a rotary nanomotor with controllable rotation, which is critical for its applications in a nanomachine.Understanding the wetting properties of reservoir rocks can be of great benefit for advanced applications such as the effective trapping and geological storage of CO2. Despite their importance, not all mechanisms responsible for wetting mineral surfaces in subsurface environments are well understood. Factors such as temperature, pressure and salinity are often studied, achieving results with little unanimity; other possible factors are left somewhat unexplored. One such factor is the effect of contamination. In the present study, the effects of adding a non-aqueous organic contaminant, ethanol, on the CO2-water interfacial tension (IFT) and the CO2/water/calcite contact angle were investigated using molecular dynamics simulations. Within the conditions studied, relatively small amounts of ethanol cause a significant decrease in the CO2-water IFTs, as well as a pronounced increase in the water-calcite-CO2 three phase contact angle. The latter result is due to the decrease of the IFT between CO2 and water and the strong adsorption of ethanol on the solid substrate.