Various shaped-ZnO nanocrystals via low temperature synthetic methods: Surfactant and pH dependence

ZnO nanocrystals, rod-, carnation-, and flower-like structures, have been synthesized in a high yield through low-temperature synthetic methods. Well-aligned ZnO nanorods having hexagonal wurtzite structure were grown on the ZnO thin films assembled by a spin-coating method. The morphologies of ZnO seed films are affected by pHs of sol–gel solutions, resulting smaller sizes and homogeneous roughness at higher pHs and higher number of spin-coating times. The carnation-like structures, average size of about 2–3 μm, were assembled by tens of uniform ZnO nanosheet petals of ∼50 nm in thickness when a different volume ratio of the precursory solution was used. ZnO nanocrystals on the facets of the compact ZnO nanorods have grown to linear nanorods having an average diameter of ∼500 nm and length of ∼2 μm. Furthermore, a noticeable difference in the growth of ZnO nanocrystals in the presence of various surfactants, polyvinylpyrrolidone, polyvinylsulphonic acid, and polyethyleneimine, has been observed and discussed.     

Effect of Non‐Specifically Adsorbed Ions on the Surface Oxidation of Pt(111)

The oxidation processes of a Pt(111) electrode in alkaline electrolytes depend on non‐specifically adsorbed ions according to in situ X‐ray diffraction and infrared spectroscopic measurements. In an aqueous solution of LiOH, an OH_ad adlayer is formed in the first oxidation step of the Pt(111) electrode as a result of the strong interaction between Li⁺ and OH_ad, whereas Pt oxidation proceeds without OH_ad formation in CsOH solution. Structural analysis by X‐ray diffraction indicates that Li⁺ is strongly protective against surface roughening caused by subsurface oxidation. Although Cs⁺ is situated near the Pt surface, the weak protective effect of Cs⁺ results in irreversible surface roughening due to subsurface oxidation.     

Temperature-Dependent Surface-Enrichment Effects of Imidazolium-Based Ionic Liquids

We present the first systematic study of the influence of temperature on the degree of surface enrichment of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs). Using angle-resolved X-ray photoelectron spectroscopy, we demonstrate that the degree of surface enrichment strongly decreases with increasing temperature for all the studied ILs. For ILs with the same cation, but different anions, [C₈C₁Im]Br, [C₈C₁Im][TfO] and [C₈C₁Im][Tf₂N], no significant differences of the temperature-induced partial loss of surface enrichment are found. Measurements for [C₄C₁Im][TfO], [C₈C₁Im][TfO] and [C₁₈C₁Im][TfO] indicate a small effect of the chain length. For [C₁₈C₁Im][TfO], a continuous decrease of alkyl surface enrichment is found with increasing temperature, with no abrupt changes at the phase-transition temperature from the smectic A to the isotropic phase, indicating that the surface enrichment is not affected by this phase transition.     

氯化铜的少溶剂固态连串配位化学反应

在少量水的存在下,由于 NH₄[CuCl₃]对水不稳定,CuCl₂·2H₂O 与氯化铵的配位化学反应只能得到 1:2 产物(NH₄)₂[CuCl₄(H₂O)₂];但在无水乙醇中,无水 CuCl₂与氯化铵按 1:1或 1:2的物质的量之比混合时,能相应地得到 NH₄[CuCl₃]或(NH₄)₂[CuCl₄]。CuCl₂·2H₂O与 2,2''-联吡啶(bipy)的少溶剂固态化学反应仍能像固态化学反应一样,根据反应物的配比生成相应的唯一产物,但在物质的量之比为1:1的反应中发现1:2产物曾经形成。热力学分析说明,如果连串反应的后一步的Δ_rG^⊖大于前一步的,则上述反应现象是可能的。     

基于两个取代四甲基环戊二烯基配体的金属羰基化合物的合成及晶体结构

配体[C₅Me₄HR][R=4-BrPh(1),(MeC₅H₃N)CH₂(2)]分别与Mo(CO)₆,Ru₃(CO)₁₂和Fe(CO)₅在二甲苯中加热回流,得到了6个双核配合物trans-[η⁵-C₅Me₄R]₂Mo₂(CO)₆(3,4),trans-[(η⁵-C₅Me₄R)Ru(CO)(μ-CO)]₂(5,6)和trans-[η⁵-(C₅Me₄R)Fe(CO)(μ-CO)]₂(7,8,).通过元素分析、红外光谱、核磁共振氢谱对配合物的结构进行了表征,并用X-射线单晶衍射法测定了配合物3,5,6和8的结构.     

A selective electromembrane extraction of uranium (VI) prior to its fluorometric determination in water

A novel method for the selective electromembrane extraction (EME) of U⁶⁺ prior to fluorometric determination has been proposed. The effect of extraction conditions including supported liquid membrane (SLM) composition, extraction time and extraction voltage were investigated. An SLM composition of 1% di-2-ethyl hexyl phosphonic acid in nitrophenyl octyl ether (NPOE) showed good selectivity, recovery and enrichment factor. The best performance was achieved at an extraction potential of 80 volts and an extraction time of 14 minutes Under the optimized conditions, a linear range from 1 to 1000 ng mL⁻¹ and LOD of 0.1 ng mL⁻¹ were obtained for the determination of U⁶⁺. The EME method showed good performance in sample cleanup and the reduction of the interfering effects of Mn²⁺, Zn²⁺, Cd²⁺, Ni²⁺, Fe³⁺, Co²⁺, Cu²⁺, Cl⁻ and PO₄³⁻ ions during fluorometric determination of uranium in real water samples. The recoveries above 54% and enrichment factors above 64.7 were obtained by the proposed method for real sample analysis.     

Synthesis,Crystal Structure,Photophysical and Electrochemical Properties of rac‐6,13‐Dihydro‐6,13‐methanopentacene

The title compound, rac‐6,13‐dihydro‐6,13‐methanopentacene ( 1 ), has been synthesized and characterized by elemental analysis, FT‐IR, ¹H NMR, UV‐Vis, HRMS spectra, cyclic voltammetry and single‐crystal X‐ray diffraction. The crystal belongs to orthorhombic, space group P2₁2₁2₁, with Z = 4 and cell dimensions a = 6.0185(4), b = 8.1914(6), c = 31.4080(19) Å. In the crystal structure, two types of intermolecular C–H···π hydrogen bonds are observed, and further stabilize the crystal structure. Its photophysical and electrochemical properties and complementary density functional theory (DFT) calculations are reported.     

Tailoring the morphology and properties of waterborne polyurethanes by the procedure of cellulose nanocrystal incorporation

Polyurethane waterborne synthesis was performed using a two-step method, commonly referred to as a prepolymer method. Nanocomposites based on waterborne polyurethane and cellulose nanocrystals were prepared by the prepolymer method by altering the mode and step in which the nanofillers were incorporated during the polyurethane formation. The morphology, structural, thermal, and mechanical properties of the resulting nanocomposite films were evaluated by Fourier transform infrared spectroscopy (FTIR), small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and tensile tests. FTIR results indicated that the degree of interaction between the nanofillers and the WPU through hydrogen bonds could be controlled by the method of cellulose nanocrystal incorporation. Data obtained from SAXS experiments showed that the cellulose nanocrystals as well as the step of the reaction in which they are added influenced the morphology of the polyurethane. The reinforcing effect of CNCs on the nanocomposites depends on their morphology.     

A novel kind of dimmer (excimer)-induced-AIE compound 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one as high selective bisulfite anion probe

An interesting dimmer (excimer)-induced-AIE characteristic of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one was observed. By using a ring-opening reaction, we developed a novel fluorescent probe based on sub-micron particles of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one in water.     

Preparation,Crystal Structure,and Thermal Decomposition of the Intriguing Five‐coordinated Compound [Cu(IMI)4Cl]Cl (IMI = Imidazole)

The intriguing multi‐ligand compound [Cu(IMI)₄Cl]Cl ( 1 ) with the ligand imidazole (IMI) was synthesized and characterized by elemental analysis and FT‐IR spectroscopy. The crystal structure was determined by X‐ray single crystal diffraction and the crystallographic data showed that the compound belongs to the monoclinic P2₁/n space group [α = 8.847(2) Å, b = 13.210(3) Å, c = 13.870(3) Å, and β = 90.164(3)°]. Furthermore, the Cu^II ion is five‐coordinated by four nitrogen atoms from four imidazole ligands and a chlorine atom. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetric (TG‐DTG) analysis. The non‐isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa's method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (ΔS^≠), enthalpy of activation (ΔH^≠), and free energy of activation (ΔG^≠) were measured and calculated.