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[en] Several novel disubstituted benzene-bridged bisimidazole derivatives (3a–3h) were prepared and characterized. Their optical properties, crystal structures and quantum chemical calculations were also investigated. The UV–vis spectra observed (λAbsmax: 325–348 nm) in acetonitrile showed low optical band gaps (Egopt: 2.89–3.25 eV). All these compounds display strong fluorescence in solution with emission spectra (λEmmax: 389.5–418 nm) (fluorescence quantum yield in the range 0.46–0.95) and significant Stokes shift (3670–5490 cm−1). The single crystal structures of 3h solvates were presented and discussed. The space groups of 3h solvates (3h1: 3h·2H2O and 3h2: 3h·DMSO·2H2O) were C2/c and P21/c, respectively. Quantum chemical calculations using DFT B3LYP/6-31G(d) showed obvious difference in LUMO (−1.273 to −1.715 eV) and HOMO (−4.838 to −5.296 eV) while they were similar in Egcal (3.393–3.599 eV) values of these compounds. These results demonstrate that these novel disubstituted benzene-bridged bisimidazole derivatives are promising electron-transporting electro luminescent materials and blue-light emitting materials for OLED. -- Highlights: • A series of novel benzene-bridged bisimidazole derivatives were synthesized. • The spectral and photophysical properties were investigated. • The crystal structures and ground state electronic structures (DFT) were discussed
[en] The metal-deposited magnetic catalyst microspheres (MCM-MPs) were successfully synthesized by one facile, high yield and controllable approach. Here, the bare magnetic microspheres were firstly synthesized according to the solvothermal method. Then silica shell were coated on the surface of the magnetic microspheres via sol–gel method, and subsequently with surface modifying with amino in the purpose to form SiO_2–NH_2 shell. Thus, metal particles were easily adsorbed into the SiO_2–NH_2 shell and in-situ reduced by NaBH_4 solution. All the obtained products (MCM-Cu, MCM-Ag, MCM-Pd) which were monodisperse and constitutionally stable were exhibited high magnetization and excellent catalytic activity towards dyes solution reduction. The catalytic rate ratio of MCM-Pd: MCM-Cu: MCM-Ag could be 10:3:1. Besides, some special coordination compound Cu_2(OH)_3Br had been generated in the in-situ reduced process of MCM-Cu, which produced superior cyclical stability (>20 times) than that of MCM-Ag and MCM-Pd. In all, those highly reusability and great catalytic efficiency of MCM-MPs show promising and great potential for treatment of dye-contaminated water. - Graphical abstract: Surface loaded metal particles magnetic catalyst microspheres MCM-MPs for rapid decolorizing dye-contaminated water: Synthesis, characterization and possible mechanisms. - Highlights: • A simple and high yield synthetic method for fabricate multi MCM-MPs is proposed with adequately optimize. • The highest reusability of MCM-Cu is attribute to the coordination compounds Cu_2(OH)_3Br. • MCM-MPs show excellent catalytic properties under different situations for various dyes • The catalytic mechanism of MCM-MPs is presented.
[en] Two kinds of high power scanning circuits for electron beams is described. Scanning homogeneities of more than 90% were experimentally achieved. They can be used in electron accelerators with energies of up to 20 MeV
[en] We put forward a model Hamiltonian to describe the influence of backbone energetics on charge transport through guanine-quadruplex DNA (G4-DNA) molecules. Our analytical results show that an energy gap can be produced in the energy spectrum of G4-DNA by hybridization effects between the backbone and the base and by on-site energy difference of the backbone from the base. The environmental effects are investigated by introducing different types of disorder into the backbone sites. Our numerical results suggest that the localization length of G4-DNA can be significantly enhanced by increasing the backbone disorder degree when the environment-induced disorder is sufficiently large. There exists a backbone disorder-induced semiconducting-metallic transition in short G4-DNA molecules, where G4-DNA behaves as a semiconductor if the backbone disorder is weak and behaves as a conductor if the backbone disorder degree surpasses a critical value.
[en] The geometries, stability, electronic properties and magnetism of ScnO clusters up to n = 12 are systematically studied using density-functional theory. For the lowest energy structures of ScnO clusters, the equilibrium site of the O atom is located in the centre of the cluster and surrounded by the Sc atoms except for n = 2, 3 and 5. The calculated results show that clusters with n = 2, 6, 9 and 12 are more stable than their respective neighbours. In addition, the ionization potential (IP), the electron affinity (EA) and the HOMO-LUMO gaps are calculated and discussed. The total magnetic moments of ScnO clusters are larger than YnO except for n = 3 and 5, and also larger than the pure Scn at n = 4 and 7-12, indicating that the O atom can dramatically modify the magnetic properties of Scn, consistent with the observation of enhanced magnetic moments in the ScnO clusters. The lowest energy structure of the Sc12O cluster is a perfect icosahedron with the largest magnetic moment, 10 μB, in the investigated clusters. In addition, we find that the total magnetic moment is not quenched in small ScnO (n = 2-12) clusters. The possible reasons for the high magnetic moments of the clusters are also discussed.
[en] In view of the characteristics of pellets, the relation between perpendicularity and end circular run-out error was analyzed, and the perpendicularity detection system for nuclear fuel pellets was designed. Using the grating displacement transducer for measuring end circular run-out error during the pellet rotation course driven by a rotation stage, the system realized the pellet automatic detection.It obtained the resolution over 0.5 μm, the accuracy over 3.0 μm and the speed 3 pellets/min, and the functions such as data displaying in real time, rapid storage, alarm, and automatic report generation were endowed. The actual operation results indicated that the system was secure,stable and reliable. (authors)
[en] A novel method was developed to produce 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) by oxygen catalyzed by iron(II) phthalocyanine (FePc) and copper(II) phthalocyanine (CuPc). The order of activity for oxidation of NMST was found to be: FePc > CuPc. Meanwhile, major reaction parameters such as concentrations of catalyst and NaOH, reaction temperature and oxygen pressure have been investigated. Through optimization of the reaction parameters, the highest yield of NMSBA and conversion of NMST (up to 53%, 89.3%, respectively) were achieved with oxygen (2.0 MPa), FePc (), NaOH (), in methanol at 55 for 8 h. A plausible mechanism for this catalytic process is proposed which involved deprotonation and radical pathways.
Graphical AbstractA novel method to produce 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) by oxygen catalyzed by iron(II) phthalocyanine (FePc) and copper(II) phthalocyanine (CuPc) has been developed. The reaction parameters and mechanism were studied. The catalytic system will be readily applicable to large-scale production of NMSBA. .
[en] We investigate the dynamics of one electron wave packet in a linear chain with random on-site energies and a nonadiabatic electron-phonon interaction which is described by a delayed cubic nonlinear term in the time-dependent Schroedinger equation. We show that in the regime where the wave packet is delocalized in the case with only the delayed nonlinearity, the wave packet becomes localized when the disorder is added and the localization is enhanced by increasing the disorder. In the regime where the self-trapping phenomenon occurs in the case with only the delayed nonlinearity, by adding the disorder the general dynamical features of the wave packet do not change if the nonlinearity parameter is small, but the dynamics shows the subdiffusive behavior if the nonlinearity parameter is large. The numerical results demonstrate complicated wave packet dynamics of systems with both the disorder and nonlinearity.
[en] A class of highly fluorescent and stable carbazole end-capped phenylene ethynylene compounds have been synthesized and the comparative photophysical studies are presented. These compounds exhibit intense violet-blue emission in CH2Cl2 solution (λmaxem∼383-420 nm, ΦF∼0.36-0.88, τF∼1.14-6.63 ns), and show a red-shifted emission in the solid state relative to that in solution. The extent of the shift is highly dependent on the nature of the substituents and the π-conjugation length of phenylene ethynylene component. Their photophysical properties and structural characterization have been investigated with the aim to provide a basis for elucidating the structure-property correlations and developing new blue-emitting materials in organic light-emitting diodes (OLEDs). - Highlights: → Synthesis of carbazole end-capped phenylene ethynylene compounds bearing different chromophores. → Structure of products was characterized via spectroscopic techniques and single crystal X-ray crystallography. → Luminescent properties were characterized by UV-vis absorption and emission in both solution and solid state.
[en] A class of highly fluorescent and stable carbazole end-capped phenylene ethynylene compounds have been synthesized and characterized. They show high extinction coefficients of absorption (λmaxabs=330-340nm) and quantum yields of fluorescence (λmaxem=393-396nm; ΦF=0.52-0.73) in dichloromethane. The solid state absorptions and emissions are significantly red-shifted from the dilute solution ones (λmaxabs=358-375nm; λmaxem=396-458nm). Their photoluminescent properties and crystal structures have been investigated with the aim of providing a basis for elucidating the structure-physical property relationships. These data indicate their potential use as blue-emitting materials in organic light-emitting diodes (OLEDs).