Orbital Distribution Research Articles

Density functional theory study on the enhanced adsorption mechanism of VOCs by Cu4 cluster decorated UiO-66

Volatile organic compounds (VOCs) are a class of air pollutants that greatly harm human health and the ecological environment, convenient and effective treatment of VOCs has become a challenge. This work proposed a transition metal cluster decorated UiO-66 (a typical type of metal-organic framework) as the effective adsorbent for the purification of VOCs with typical functional groups based on density functional theory (DFT) calculations. The results show that the VOCs adsorption energy on the modified UiO-66 increased significantly, especially for Cu4 cluster-modified UiO-66, and the adsorption energy of trichloroethene is greater than that of the other considered VOCs, which may be induced by halogens or carbon-carbon double bond in trichloroethene. We compared chloromethane, chloroethylene, and ethylene and found that VOCs with carbon-carbon double bond have stronger adsorption energy, increasing with the number of chlorine atoms. The density of states (DOS), Hirshfeld charge analysis, and orbital distribution further confirm the charge distribution in UiO-66 after the decoration of the Cu4 cluster. Cu4 cluster can act as a bridge to promote the formation of chemical bonds between UiO-66 and VOCs molecules. Therefore, Cu4 cluster-modified UiO-66 can be a promising VOCs adsorption material, especially for vinyl chloride molecules.

Dynamics of 2023 FW14, the second L4 Mars trojan, and a physical characterization using the 10.4 m Gran Telescopio Canarias

Context. Known Mars trojans could be primordial small bodies that have remained in their present-day orbits for the age of the Solar System. Their orbital distribution is strongly asymmetric; there are over a dozen objects at the L5 point and just one at L4, (121514) 1999 UJ7. Most L5 trojans appear to form a collision-induced asteroid cluster, known as the Eureka family. Asteroid 2023 FW14 was recently discovered and it has a robust orbit determination that may be consistent with a Mars trojan status. Aims. Our aim is determine the nature and dynamical properties of 2023 FW14. Methods. We carried out an observational study of 2023 FW14 to derive its spectral class using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias. We investigated its possible trojan resonance with Mars using direct N-body simulations. Results. The reflectance spectrum of 2023 FW14 is not compatible with the olivine-rich composition of the Eureka family; it also does not resemble the composition of the Moon, although (101429) 1998 VF31 does. The Eureka family and 101429 are at the L5 point. The spectrum of 2023 FW14 is also different from two out of the three spectra in the literature of the other known L4 trojan, 121514, which are of C-type. The visible spectrum of 2023 FW14 is consistent with that of an X-type asteroid, as is the third spectrum of 121514. Our calculations confirm that 2023 FW14 is the second known L4 Mars trojan although it is unlikely to be primordial; it may remain in its present-day “tadpole” path for several million years before transferring to a Mars-crossing orbit. It might be a fragment of 121514, but a capture scenario seems more likely. Conclusions. The discovery of 2023 FW14 suggests that regular Mars-crossing asteroids can be captured as temporary Mars trojans.

The phase-space distribution of the M 81 satellite system

The spatial distribution of dwarf galaxies around their host galaxies is a critical test for the standard model of cosmology because it probes the dynamics of dark matter halos and is independent of the internal baryonic processes of galaxies. Comoving planes of satellites have been found around the Milky Way, the Andromeda galaxy, and the nearby Cen A galaxy, which seems to be at odds with the standard model of galaxy formation. Another nearby galaxy group, with a putative flattened distribution of dwarf galaxies, is the M 81 group. In this paper, we present a quantitative analysis of the distribution of the M 81 satellites using a Hough transform to detect linear structures. Using this method, we confirm a flattened distribution of the dwarf galaxies. Depending on the morphological type, we find a minor-to-major axis ratio of the satellite distribution of 0.5 (all types) or 0.3 (dSph), which is in line with previous results for the M 81 group. Comparing the orientation of this flattened structure in 3D with the surrounding large-scale matter distribution, we find a strong alignment with the local sheet and the planes of satellites around the Andromeda galaxy and Cen A. Furthermore, the satellite system seems to be lopsided. Employing line-of-sight velocities for a subsample of the dwarfs, we find no signal of corotation. Comparing the flattening and motion of the M 81 dwarf galaxy system with TNG50 of the IllustrisTNG suite we find good agreement between observations and simulations, but caution that i) velocity information of half of the satellite population is still missing, ii) current velocities mainly come from dwarf irregulars clustered around NGC 3077, which may indicate an infall of a dwarf galaxy group, and iii) some of the dwarfs in our sample may be tidal dwarf galaxies. From the missing velocities, we predict that the observed frequency within IllustrisTNG may still range between 2 to 29%. Any final conclusions about the agreement or disagreement with cosmological models needs to wait for a more complete picture of the dwarf galaxy system.

The origin of lopsided satellite galaxy distribution around isolated systems in MillenniumTNG

ABSTRACT Dwarf satellites in galaxy groups are distributed in an anisotropic and asymmetric manner, which is called the ‘lopsided satellite distribution’. This lopsided signal has been observed not only in galaxy pairs but also in isolated systems. However, the physical origin of the lopsided signal in isolated systems is still unknown. In this work, we investigate this in the state-of-the-art hydrodynamical simulation of the MillenniumTNG Project by tracing each system back to high redshift. We find that the lopsided signal is dominated by satellites located in the outer regions of the halo and is also dominated by recently accreted satellites. The lopsided signal originates from the anisotropic accretion of galaxies from the surrounding large-scale structure and that, after accretion, the non-linear evolution of satellites inside the dark matter halo weakens the lopsidedness. The signal decreases as cosmic time passes because of a competition between anisotropic accretion and internal evolution within dark matter haloes. Our findings provide a useful perspective for the study of galaxy evolution, especially for the origin of the spatial satellite galaxy distributions.

Orbital and Absolute Magnitude Distribution of Jupiter Trojans

Jupiter Trojans (JTs) librate about the Lagrangian stationary centers L4 and L5 associated with this planet on typically small-eccentricity and moderate-inclination heliocentric orbits. The physical and orbital properties of JTs provide important clues about the dynamical evolution of the giant planets in the early solar system, as well as populations of planetesimals in their source regions. Here we use decade-long observations from the Catalina Sky Survey (station G96) to determine the bias-corrected orbital and magnitude distributions of JTs. We distinguish the background JT population, filling smoothly the long-term stable orbital zone about L4 and L5 points and collisional families. We find that the cumulative magnitude distribution of JTs (the background population in our case) has a steep slope for H ≤ 9, followed by a moderately shallow slope until H ≃ 14.5, beyond which the distribution becomes even shallower. At H = 15 we find a local power-law exponent 0.38 ± 0.01. We confirm the asymmetry between the magnitude-limited background populations in L4 and L5 clouds characterized by a ratio 1.45 ± 0.05 for H < 15. Our analysis suggests an asymmetry in the inclination distribution of JTs, with the L4 population being tighter and the L5 population being broader. We also provide a new catalog of the synthetic proper elements for JTs with an updated identification of statistically robust families (9 at L4, and 4 at L5). The previously known Ennomos family is found to consist of two overlapping Deiphobus and Ennomos families.

Analyzing isothermal crystallization of poly(lactic acid)/polyol systems: Correlated DSC and simulation studies

The isothermal crystallization behavior and kinetics of poly(l-lactic acid) (PLLA) melt-blended small amounts (0.7%–1%) of polyols (D-mannitol, D-sorbitol, and xylitol) were investigated by differential scanning calorimetry (DSC), and the interaction between polyols and PLLA was clarified via multiscale theoretical simulations. The decreased peak crystallization time and full width at half peak maximum (FWHM) of polyol-modified PLLA indicates that the crystallization capability of PLLA was improved, and the process was accelerated. The crystallinity remains unchanged before and after modification at the same temperature. The Avrami exponent (n) is largely unaffected, indicating that polyols as nucleation accelerants hardly alter the nucleation and growth mechanisms of PLLA crystallization. The outputs of long-term molecular dynamics simulations were fulfilled toward large-scale periodic models for three polyol-PLLA models that involved over 20,000 atoms. Therein, the interaction energies and the derived radial distribution function (RDF) implied the hydrogen bonding occurred between polyol and PLLA. To visualize the interaction sites between the polyol and PLLA, the frontier orbital distributions of the polyols were further calculated according to density functional theory (DFT). Theoretical evidence suggests that polyols improve the crystallization capability of PLLA by hydrogen bonding between the terminal hydroxyl group and the carbonyl oxygen of PLLA.

Scattering Field Intensity and Orbital Angular Momentum Spectral Distribution of Vortex Electromagnetic Beams Scattered by Electrically Large Targets Comprising Different Materials

In this study, we obtained the intensity and orbital angular momentum (OAM) spectral distribution of the scattering fields of vortex electromagnetic beams illuminating electrically large targets composed of different materials. We used the angular spectral decomposition method to decompose a vortex beam into plane waves in the spectral domain at different elevations and azimuths. We combined this method with the physical optics algorithm to calculate the scattering field distribution. The OAM spectra of the scattering field along different observation radii were analyzed using the spiral spectrum expansion method. The numerical results indicate that for beams with different parameters (such as polarization, topological charge, half-cone angle, and frequency) and targets with different characteristics (such as composition), the scattering field intensity distribution and OAM spectral characteristics varied considerably. When the beam parameters change, the results of scattering from different materials show similar changing trends. Compared with beams scattered by uncoated metal and dielectric targets, the scattering field of the coating target can better maintain the shape and OAM mode of beams from the incident field. The scattering characteristics of metal targets were the most sensitive to beam-parameter changes. The relationship between the beam parameters, target parameters, the scattering field intensity, and the OAM spectra of the scattering field was constructed, confirming that the spiral spectrum of the scattering field carries the target information. These findings can be used in remote sensing engineering to supplement existing radar imaging, laying the foundation for further identification of beam or target parameters.

Re-engineering and regulating molecular architecture of synthetic capsaicin for enhanced water-based degradation performance

Synthetic capsaicin, also known as pelargonic acid vanillylamide (PAVA), constitutes the primary component in riot control agents. Due to the propensity of PAVA agglomerated in aqueous environments, the interaction between the active site of PAVA molecular and catalyst was restricted, consequently reducing its degradation efficiency in water-based oxidizing agents. This study used a cationic surfactant, dodecyl trimethyl ammonium chloride (DTAC), in combination with KOH for the precise regulation and arrangement of PAVA molecules, resulting in the formation of a distinctive hydrophilic structure. This approach resolved its poor solubility in aqueous solutions while the relationship between solubility and degradation rate was obtained. The frontier orbital distribution and surface electrostatic potential distribution of PAVA molecular were predicted through first-principles calculation. The mechanism of PAVA solubilization was studied by 1H NMR techniques and infrared spectroscopy methods. The results showed that KOH substitutes the phenolic hydroxyl group “–OH” of PAVA, forming potassium phenoxide “–OK”, which enhanced the solubility of PAVA in water. Additionally, KOH might reduced the surface tension in the solution. It promotes the formation of the DTAC/PAVA complex micelle structure, which exhibited the PAVA agglomerates to exposing the catalytic activation reaction sites and accelerating the catalytic oxidation.

Quantum chemical explanation and APT atomic charge index of substituent orienting effect proposed by DFT calculation and MO Theory

AbstractIn organic chemistry textbooks, the electron resonance states are used to explain the orienting effect of benzene substituent. However, these resonance states do not exist in the C6H5‐S + E+ electrophilic addition, so the resonance state discussions actually are meaningless. The density functional theory (DFT) calculation shows that the C6H5‐S + E+ addition follows the transition state theory and needs to overcome a barrier. Benzene molecule C6H6 has two degenerate highest occupied molecular orbitals (HOMOs), but after becoming substituted benzenes, the two HOMOs split to HOMO and HOMO‐1 with different orbital energies and electron distributions. It makes the addition barrier on two or three benzene ring carbons is low, and the addition rate is fast, but the barrier of other carbons is high, and the rate is slow. Therefore, substituent splits the two degenerate HOMOs of benzene molecule, which is the origin of substituent orienting effect. For the substituted benzenes with halogen group ‐X and electron‐releasing group, their HOMO images alone can determine that the two types of substituents are the ortho‐ and para‐orienting groups, but for the substituted benzenes with electron‐withdrawing group, their HOMO alone cannot determine whether the substituent is a meta‐orienting group. The study found that atomic polar tensor (APT) charges are a good judgment index of substituent orienting effect because based on its physic‐chemical model, the charges represent the number of active electrons on the benzene ring carbons. The DFT calculation gives the APT charges of 19 mono‐substituted and 12 di‐substituted benzenes and some aromatic molecules. The APT charges can all correctly determine their orienting effects, showing that APT atomic charge from quantum theoretical calculation is a good substituent orienting index.

Synthesis of V-shaped Thiophene Based Rotor-Stilbene: Substituent Dependent Aggregation and Photophysical Properties.

Thiophene core V-shaped rotor-stilbene derivatives have been synthesized utilizing two-fold Heck coupling reaction. These compounds are blue emitters with moderate quantum yield in dilute solution. Rotor nature of the synthesized stilbenes supports aggregation induced emission (AIE) behaviour and they show substituent dependent emission behavior in aggregate state. In presence of donating groups (e.g., tert-butyl, methoxy, diphenylamine group) in stilbenes, they exhibit AIE property. But with the introduction of electron withdrawing group (nitro group), they shows aggregation caused quenching (ACQ) behavior. Different types of nano-aggregates formation is observed in aggregated state, which was confirmed by dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies. The details photophysical (absorption, fluorescence, and lifetime), electrochemical property (cyclic voltammetry) and thermal stability have been investigated. Optimized structure, energy and electronic distribution of molecular orbitals have been studied by theoretical calculation.

The cataclysmic variable orbital period gap: More evident than ever

Context.Recently, large and homogeneous samples of cataclysmic variables identified by the Sloan Digital Sky Survey (SDSS) were published. In these samples, the famous orbital period gap, which is a dearth of systems in the orbital period range ∼2 − 3 h and the defining feature of most evolutionary models for cataclysmic variables, has been claimed not to be clearly present. If true, this finding would completely change our picture of cataclysmic variable evolution.Aims.In this Letter we focus on potential differences with respect to the orbital period gap between cataclysmic variables in which the magnetic field of the white dwarf is strong enough to connect with that of the donor star, so-called polars, and non-polar cataclysmic variables as the white dwarf magnetic field in polars has been predicted to reduce the strength of angular momentum loss through magnetic braking.Methods.We separated the SDSS I–IV sample of cataclysmic variables into polars and non-polar systems and performed statistical tests to evaluate whether the period distributions are bimodal as predicted by the standard model for cataclysmic variable evolution or not. We also compared the SDSS I–IV period distribution of non-polars to that of other samples of cataclysmic variables.Results.We confirm the existence of a period gap in the SDSS I–IV sample of non-polar cataclysmic variables with &gt; 98% confidence. The boundaries of the orbital period gap are 147 and 191 min, with the lower boundary being different to previously published values (129 min). The orbital period distribution of polars from SDSS I–IV is clearly different and does not show a similar period gap.Conclusions.The SDSS samples as well as previous samples of cataclysmic variables are consistent with the standard theory of cataclysmic variable evolution. Magnetic braking does indeed seem get disrupted around the fully convective boundary, which causes a detached phase during cataclysmic variable evolution. In polars, the white dwarf magnetic field reduces the strength of magnetic braking and consequently the orbital period distribution of polars does not display an equally profound and extended period gap as non-polars. It remains unclear why the breaking rates derived from the rotation of single stars in open clusters favour prescriptions that are unable to explain the orbital period distribution of cataclysmic variables.

Analysis of the Unusual Chemical Bonds and Dipole Moments of AeF- (Ae=Be-Ba): A Lesson in Covalent Bonding.

Quantum chemical calculations of the anions AeF- (Ae=Be-Ba) have been carried out using ab initio methods at the CCSD(T)/def2-TZVPP level and density functional theory employing BP86 with various basis sets. The detailed bonding analyses using different charge- and energy partitioning methods show that the molecules possess three distinctively different dative bonds in the lighter species with Ae=Be, Mg and four dative bonds when Ae=Ca, Sr, Ba. The occupied 2p atomic orbitals (AOs) and to a lesser degree the occupied 2s AO of F- donate electronic charge into the vacant spx(σ) and p(π) orbitals of Be and Mg which leads to a triple bond Ae F-. The heavier Ae atoms Ca, Sr, Ba use their vacant (n-1)d AOs as acceptor orbitals which enables them to form a second σ donor bond with F- that leads to quadruply bonded Ae F- (Ae=Ca-Ba). The presentation of molecular orbitals or charge distribution using only one isodensity value may give misleading information about the overall nature of the orbital or charge distribution. Better insights are given by contour line diagrams. The ELF calculations provide monosynaptic and disynaptic basins of AeF- which nicely agree with the analysis of the occupied molecular orbitals and with the charge density difference maps. A particular feature of the covalent bonds in AeF- concerns the inductive interaction of F- with the soft valence electrons in the (n)s valence orbitals of Ae. The polarization of the (n)s2 electrons induces a (n)spx hybridized lone-pair orbital at atom Ae, which yields a large dipole moment with the negative end at Ae. The concomitant formation of a vacant (n)spx AO of atom Ae, which overlaps with the occupied 2p(σ) AO of F-, leads to a strong covalent σ bond.

The Orbital Structure and Selection Effects of the Galactic Center S-star Cluster

The orbital distribution of the S-star cluster surrounding the supermassive black hole in the center of the Milky Way is analyzed. A tight dependence of the pericenter distance r p on orbital eccentricity e ⋆ is found, log(rp)∼(1−e⋆) , which cannot be explained simply by a random distribution of semimajor axis and eccentricities. No stars are found in the region with high e ⋆ and large log(rp) or in the region with low e ⋆ and small log(rp) . Although the sample is still small, the G-clouds show a very similar distribution. The likelihood P(log(rp),(1−e⋆)) to determine the orbital parameters of S-stars is determined. P is very small for stars with large e ⋆ and large log(rp) . S-stars might exist in this region. To determine their orbital parameters, one however needs observations over a longer time period. On the other hand, if stars would exist in the region of low log(rp) and small e ⋆, their orbital parameters should by now have been determined. That this region is unpopulated therefore indicates that no S-stars exist with these orbital characteristics, providing constraints for their formation. We call this region, defined by log(rp/AU)<1.57+2.6(1−e⋆) , the zone of avoidance. Finally, it is shown that the observed frequency of eccentricities and pericenter distances is consistent with a random sampling of log(rp) and e ⋆ if one takes into account the fact that no stars exist in the zone of avoidance and that orbital parameters cannot yet be determined for stars with large r p and large e ⋆.

The distribution of stellar orbits in eagle galaxies – the effect of mergers, gas accretion, and secular evolution

ABSTRACT The merger history of a galaxy is thought to be one of the major factors determining its internal dynamics, with galaxies having undergone different types or mergers (e.g. dry, minor, or major mergers) predicted to show different dynamical properties. We study the instantaneous orbital distribution of galaxies in the eagle simulation, colouring the orbits of the stellar particles by their stellar age, in order to understand whether stars form in particular orbits (e.g. in a thin or thick disc). We first show that eagle reproduces well the observed stellar mass fractions in different stellar orbital families as a function of stellar mass and spin parameter at z = 0. We find that the youngest stars reside in a thin disc component that can extend to the very inner regions of galaxies, and that older stars have warmer orbits, with the oldest ones showing orbits consistent with both hot and counter-rotating classifications, which is consistent with the trend found in the Milky Way and other disc galaxies. We also show that counter-rotating orbits trace galaxy mergers – in particular dry mergers, and that in the absence of mergers, counter-rotating orbits can also be born from highly misaligned gas accretion that leads to star formation.

Precise recognition and efficient recovery of Pd(II) from high-level liquid waste by a novel aminothiazole-functionalized silica-based adsorbent

Efficient recognition, separation and recovery of palladium from high-level liquid waste (HLLW) not only helps the safe, green and environmentally friendly disposal of nuclear waste, but also is an essential important supplement to overcome the growing shortage of natural palladium resources. Herein, a novel silica-based functional adsorbent named 2AT-SiAaC was prepared by a two-step method, i.e., grafting of 2-aminothiazole (2AT) via the amidated reaction after in-situ polymerization of acrylic monomers on porous silica. SEM, EDS, TG-DSC, BET and PXRD all proved the successful preparation of 2AT-SiAaC, and it exhibited ultrahigh adsorption selectivity for Pd(II) (Kd (distribution coefficient) ≥ 10,344.2 mL/g, SFPd/M (separation factor) ≥ 613.7), fast adsorption kinetics with short equilibrium time (t ≤ 1 h) and good adsorption capacity (Q ≥ 62.1 mg Pd/g). The dynamic column experiments shows that 2AT-SiAaC achieved efficiently separation of Pd(II) from simulated HLLW, and the enrichment coefficients (C/C0) of Pd(II) was as high as about 14 with the recovery rate nearly 99.9% and basically kept the same performance in three adsorption-desorption column cycle experiments. The adsorption mechanism was analyzed by FT-IR, XPS and DFT calculations, and the ultrahigh selectivity of 2AT-SiAaC was attributed to the preferred affinity of the soft N-donor atoms in 2AT for Pd(II). NO3− ions participated in the adsorption reaction to keep charge balance, and the frontier orbital electron density distribution diagram shows the charge transfer in the process of material preparation and adsorption. To sum up, 2AT-SiAaC adsorbent provided a new insight for precise recognition and efficient separation of Pd(II) from HLLW.

Surgical correction of sunken upper eyelid with upper arcus marginalis release and precision fat distribution technique.

Sunken upper eyelids, characterized by hollowing in the upper orbital region, can contribute to an aged or fatigued appearance. We aim to report on the surgical technique and its effects, involving the release of the arcus marginalis of the upper eyelid and the precise distribution of orbital fat. From December 2021 to March 2023, a total of 84 eyelids from 42 patients who underwent surgical correction for sunken upper eyelids, utilizing the upper arcus marginalis release and precision fat distribution technique, were included in this study. Preoperative and postoperative sunken depths were measured and statistically analyzed. Aesthetic satisfaction was assessed through patient questionnaires. Preoperative and postoperative sunken depths measured 9.2 ± 2.2 mm and 5.9 ± 2.3 mm, respectively. The mean improvement was 3.3 mm, a change of statistical significance. Aesthetic outcomes and patient satisfaction yielded favorable results. No major complications were observed during the follow-up period. The upper arcus marginalis release and orbital fat distribution technique demonstrated favorable outcomes in correcting sunken upper eyelids. This procedure ensures stable placement of orbital fat at the deepest sunken point, resulting in aesthetically pleasing and enduring results. This technique serves as a valuable alternative for patients with moderate to severe sunken eyelids.

Tidal Disruption of Near-Earth Asteroids during Close Encounters with Terrestrial Planets

Numerical modeling has long suggested that gravitationally bound (or so-called rubble-pile) near-Earth asteroids (NEAs) can be destroyed by tidal forces during close and slow encounters with terrestrial planets. However, tidal disruptions of NEAs have never been directly observed nor have they been directly attributed to any families of NEAs. Here we show population-level evidence for the tidal disruption of NEAs during close encounters with Earth and Venus. Debiased model distributions of NEA orbits and absolute magnitudes based on observations by the Catalina Sky Survey during 2005–2012 underpredict the number of NEAs with perihelion distances coinciding with the semimajor axes of Venus and Earth. A detailed analysis of the orbital distributions of the excess NEAs shows that their characteristics agree with the prediction for tidal disruptions, and they cannot be explained by observational selection effects or orbital dynamics. Accounting for tidal disruptions in evolutionary models of the NEA population partly bridges the gap between the predicted rate of impacts by asteroids with diameters of tens of meters and observed statistics of fireballs in the same size range.

Interactions and reactivity in crystalline intermediates of mechanochemical cyclorhodation reactions.

There is experimental evidence that solid mixtures of the rhodium dimer [Cp*RhCl2]2 and benzo[h] quinoline (BHQ) produce two different polymorphic molecular cocrystals called 4α and 4β under ball milling conditions. The addition of NaOAc to the mixture leads to the formation of the rhodacycle [Cp*Rh-(BHQ)Cl], where the central Rh atom retains its tetracoordinate character. Isolate 4β reacts with NaOAc leading to the same rhodacycle while isolate 4α does not under the same conditions. We show that the puzzling difference in reactivity between the two cocrystals can be traced back to fundamental aspects of the intermolecular interactions between the BHQ and [Cp*RhCl2]2 fragments in the crystalline environment. To support this view, we report a number of descriptors of the nature and strength of chemical bonds and intermolecular interactions in the extended solids and in a cluster model. We calculate formal quantum mechanical descriptors based on electronic structure, electron density, and binding and interaction energies including an energy decomposition analysis. Without exception, all descriptors point to 4β being a transient structure higher in energy than 4α with larger local and global electrophilic and nucleophilic powers, a more favorable spatial and energetic distribution of the frontier orbitals, and a more fragile crystal structure.

Understanding and tuning the electronic structure of pentalenides.

Here we report the first example of systematic tuning of the electronic properties of dianionic pentalenides through a straightforward synthetic protocol which allows the controlled variation of substituents in the 1,3,4,6-positions to produce nine new compounds, representing the largest pentalenide study to date. Both electron-withdrawing as well as electron-donating aromatics have been incorporated to achieve different polarisations of the bicyclic 10π aromatic core as indicated by characteristic 1H and 13C NMR shifts and evaluated by DFT calculations including nucleus-independent chemical shift (NICS) scans, anisotropy of the induced current density (ACID) calculations, and natural bond orbital (NBO) charge distribution analysis. The introduction of methyl substituents to the pentalenide core required positional control in the dihydropentalene precursor to avoid exocyclic deprotonation during the metalation. Frontier orbital analyses showed arylated pentalenides to be slightly weaker donors but much better acceptor ligands than unsubstituted pentalenide. The coordination chemistry potential of our new ligands has been exemplified by the straightforward synthesis of a polarised anti-dirhodium(i) complex.

Adsorption configuration and assembly structure of vanadyl phthalocyanine molecule on copper oxide layer

In recent years, regulating organic functional molecule has gradually received much attention in the field of materials due to its significant contribution in improving the charge carrier mobility of nanometer optoelectronic device. Molecular configuration and assembly structure of vanadyl phthalocyanine (VOPc) are systemically investigated on pristine and oxidized Cu(110) surface by using low temperature scanning tunneling microscopy. In the initial deposition stage, two molecular adsorption configurations, referring to O-up and O-down, are randomly distributed on the pristine Cu(110) surface. By oxidizing Cu(110) at different oxygen atmospheres and substrate temperatures, two different copper oxide structures are obtained, i.e. CuO-(2×1) and Cu&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;-c(6×2). The VOPc molecules are then deposited on both surfaces via thermal evaporation. For the CuO-(2×1) surface, contrastly, extended molecular chains form in the initial adsorption and subsequently the VOPc molecules assemble into an ordered molecular film involving both configurations. The VOPc molecules shows two packing orientations with a rotation angle of about 36° relative to each other. On Cu&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;-c(6×2), the O-down and O-up molecules are isolatedly adsorbed at the initial coverage. As the coverage increases, molecular assembly film gradually forms a parallelogram-shaped unit cell that involves only the O-up molecules. The molecular film exhibits two distinct molecular orientations with a rotation angle of about 42° relative to each other. The dipole-dipole interaction drives the configuration transition from the O-up configuration to O-down configuration. The O-down VOPc molecules of the second layer tend to be adsorbed on the molecular membrane supported by the Cu&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;-c(6×2) surface. The dipole-dipole interaction between neighboring molecular layers may be responsible for the preferable adsorption of the second-layered molecules. This study suggests the importance of surface oxidization in modifying configurations and orbital distributions of adsorbed molecules that can affect the charge transport in molecular films during fabricating electronic devices.