Synthesis,Crystal Structures,and Magnetic Properties of Two Copper(II) Radical Heterospin Complexes

Two heterospin complexes [Cu(NIT3Py)(cda)H₂O] · H₂O ( 1 ) and [Cu(NIT2Py)(cda)H₂O] · H₂O · CH₃OH ( 2 ) with Cu^II ions and pyridyl‐substituted nitronyl nitroxide radicals (NITxPy = 2‐(x′‐pyridyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide, x = 3, 2; H₂cda = 4‐hydroxy‐pyridine‐2,6‐dicarboxylic acid) were synthesized and characterized structurally and magnetically. The single crystal structures show that the two complexes are both two‐spin complexes, in which the different radicals make the two complexes have different hydrogen bonding interactions to form 2D and 1D supramolecular network for complexes 1 and 2 , respectively. The magnetic measurements indicate that complexes 1 and 2 both exhibit antiferromagnetic interactions between Cu^II and radicals.     

Dinuclear Macrocyclic Quinoline Bridged Mercury and Silver Bis(N‐heterocyclic Carbene) Complexes: Synthesis,Structure, and Spectroscopic Studies

Quinoline bridged imidazolium precursors 5,8‐bis(N‐R‐imidazolylidenylmethylene)quinoline PF₆^– salts [H₂L](PF₆)₂ [R = Me ( 1a ), R = naphthylmethyl ( 1b )] were prepared by quaternization of N‐methylimidazole and N‐naphthylmethylimidazole with 5,8‐bis(bromomethyl)quinoline, respectively. Reaction of the imidazolium ligands 1a and 1b with Hg(OAc)₂ and Ag₂O in acetonitrile gave the macrocyclic transition metal carbene complexes [Hg₂L₂](PF₆)₄ ( 2a and 2b ) and [Ag₂L₂](PF₆)₂ ( 3a and 3b ), respectively. All the N‐heterocyclic carbene complexes were characterized in detail by NMR, ESI‐MS, and elemental analysis. Structures of complexes 2a and 3a were determined by X‐ray diffraction studies. Structural studies revealed that the coordination arrangement of the central mercury atom in complex 2a displays a tricoordinate mode and the molecular conformation results in a“closed” form with the bridging quinoline functionality in the macrocycle, whereas the silver complex 3a does not show an coordiantion between the bridging quinoline and the Ag^I ion, which results in an “open” conformation of the macrocycle. The Hg^II and Ag^I NHC complexes showed similar UV absorption and luminescence in acetonitrile solutions.     

The effect of ionic strength on the diffusion of 125I in Gaomiaozi bentonite

The diffusion of ¹²⁵I^? in compacted Gaomiaozi (GMZ) bentonite was investigated by capillary in-diffusion method. Apparent and effective diffusion coefficients and accessible porosity of iodide in GMZ bentonite were obtained, and the effect of ionic strength on diffusion parameters was studied. The apparent diffusion coefficients of iodide in compacted GMZ bentonite are in the range of 1.0–6.0 × 10^?10 m² s^?1 under the conditions of dry bulk density 1,500 kg m^?3 and temperature 298 K, and increase with increasing ionic strength. This effect was explained through the analysis of microscopic structure of compacted bentonite. The iodide can only diffuse in unbound interparticle pore solution of compacted bentonite. The apparent diffusion coefficient is a function of accessible porosity which is decided by the thickness of diffusion double layer, and the thickness is in turn controlled by ionic strength.     

Studies on the Effects of Additional Components on Micellization of CTAB via Surface Tension Measurements

The effects of Tris-HCl buffer solution on the cmc of cetyltrimethylammonium bromide (CTAB) were studied by surface tension measurement. The result shows that the effect of the buffer solution depends on the interaction between CTAB and NaCl and the structure accelerants of water, Tris. A series of parameters, including the critical micelle concentration (cmc), the surface tension at cmc (γ_cmc), the adsorption efficiency (pC₂₀), and the effectiveness of surface tension reduction (∏_cmc) were obtained from the surface tension measurements in the presence of glycine with different concentration in the Tris-HCl buffer solution at 27°C. In addition, maximum surface excess concentration (Γ _max) and minimum surface area per molecule (A_min) at the air-water interface were estimated according to the Gibbs adsorption isotherm. The thermodynamic parameters (Δ C _p,m , Δ H _m,tr , Δ C _p,m,tr ) of micellization for CTAB in the absence and presence of glycine at different temperature were also been obtained.     

Migration study of iodine in Beishan granite by a column method

The fate and migration behavior of radionuclides in environment are influenced by a series of physical and chemical processes such as advection, hydrodynamic dispersion (including mechanical dispersion and molecular diffusion), retention, chemical reaction and so on. In this study, the migration of ¹²⁵I^? in Beishan granite and the potential retention of iodine by silver halide additives were investigated by a pulse injection column method. All breakthrough curves were analyzed according to the analytical solution of transport equation and the dispersion coefficient (D), and first-order sorption constant (k) were obtained. For conservative nuclide, the dispersion behavior is only related to the dispersion medium. Silver halides were proved having sorption ability for ¹²⁵I^? in the order of AgCl > AgBr > AgI. The transport of iodine in the crushed granite column can be adequately described by the advection–dispersion equation with a first-order, irreversible sorption term. The pulse injection column method can be used as a fast method to evaluate the sorption or retention ability of solid phase.     

交联聚乙烯基吡咯烷酮快速前处理方法结合液相色谱-串联质谱分析红葡萄酒中酪蛋白过敏原

建立了红葡萄酒酪蛋白过敏原的质谱分析方法。选择专一性SRM离子对,建立3种亚型酪蛋白α-S1,α-S2,β的质谱定性与定量方法;利用交联聚乙烯基吡咯烷酮(PVPP)处理红葡萄酒有效提取蛋白,并直接快速酶解,使前处理缩短到2 h以内。结果表明,酪蛋白的回收率提高到80%以上,检出限达10μg/L。     

A real-time AFM study on crystal nucleation and growth in nanodroplets of isotactic polypropylene

Isotactic polypropylene (iPP) nanodroplets were prepared by using the classical droplet method in this study. The formation of nanodroplets allowed the controlled observation of polymer nucleation as well as access to crystal growth at exceptionally high supercooling in iPP. Three cases including the heterogeneous nucleation and fast crystallization in iPP droplets, the formation of multiple independent homogeneous nuclei within a single droplet and a single nucleus within a single droplet were detected by using atomic force microscopy (AFM) during gradually cooling after remelting the nanodroplets. Moreover, it is found that when the volume of droplet is larger than the value of ca. 130000 nm3, the first case was observed. Otherwise, the latter two cases appeared. The temperature at which the onset of nucleation was observed in individual droplets was found to be mainly dependent on height of the droplets when the size scale of the droplet is comparable to the size of the critical nucleus in at least one dimension, which indicates the nucleation behavior under confinement.     

Influence of clay on the morphology and phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blends

The effect of clay on the morphology and phase-separation behavior of poly(methyl methacrylate)/poly(styreneco-acrylonitrile)(PMMA/SAN) blends and the variation of clay dispersion have been investigated. With the evolution of phase separation in PMMA/SAN, most of the clays are first located at the boundaries between PMMA and SAN, and then gradually move to the PMMA-rich domain, owing to the affinity of clay to PMMA. The introduction of clay causes the increase of binodal and spinodal temperatures of PMMA/SAN and enlarges their metastable region, indicating the phase stabilizing effect of clay on the matrix. But the influence of clay on the cloud points obviously depends on the composition of PMMA/SAN. The selective adsorption of PMMA on the clay results in the difference between the composition of surface layer and that of polymer matrix. Hence, the clay plays the role of an agent changing the conditions of phase structure formation.     

Dynamics of viscous fingers in Hele-Shaw cells of liquid crystals Theory and experiment

The theoretical and experimental developments in the interfacial dynamics and the formation of viscous fingering patterns in Hele-Shaw cells of liquid crystal-air systems are summarized and discussed. These include radial and linear cells with or without grooves engraved on the cell plates. Instabilities of fingers, the role of intrinsic and extrinsic anisotropies, etc., are emphasized. In a linear cell, when the injected air is kept at constant pressure, a whole sequence of successive instabilities of fingers (hump, tip-splitting, sidewrinkling, sidebranching and DLA-like structure) is observed in a single run of the experiment. In our theory, the equations of motion of nematic flows in Hele-Shaw cells are derived from the Ericksen-Leslie equations. In the linear approximation, the equations resemble those of isotropic liquids with the presence of effective viscosities and anisotropic surface tension. Experimental observations are interpreted with the introduction of an effective control parameter which may be time dependent. Special features of viscous fingers in liquid crystals in contrast to those in isotropic liquids, such as asymmetric dendritics, displacement of the finger from the central axis of the linear cell, and reentrant sequence of patterns, are pointed out. Plausible explanations of these phenomena are given. In this newly developed field, a large number of interesting problems remain to be solved.     

Self-assembly behavior of fluorocarbon-end-capped poly(glycerol methacrylate) in aqueous solution

Well-defined perfluoroalkyl-terminated poly(glycerol methacrylate) (R _F-PGMA) semitelechelics are prepared by atom transfer radical polymerization and copper(I)-catalyzed alkyne–azide cycloaddition reaction. R _F-PGMA has a similar architecture as the well-studied perfluorinated poly(ethylene oxide) (R _F-PEO) semitelechelics but bears two hydroxyl groups on each glycerol methacrylate unit. Because of the strong hydrophobic interaction of the perfluoroalkyl group, R _F-PGMA semitelechelics self-associate to form core–corona spherical micelles in water above the critical micellization concentration (cmc) which depends on poly(glycerol methacrylate) (PGMA) content and temperature. For comparison, the R _F-PEO semitelechelics with the same perfluoroalkyl terminal group as R _F-PGMA are also prepared. The cmc values of R _F-PGMA semitelechelics are found to increase with increasing temperature in water, which is opposite to the tendency of R _F-PEO semitelechelics. According to the thermodynamic studies, the micellization process of R _F-PGMA in aqueous solution is driven by both a negative enthalpy and an increase of entropy, whereas the micellization of R _F-PEO is an entropy-driven process exhibiting a positive micellization enthalpy. This striking different behavior originates from intra-/intermolecular hydrogen bonds between the hydroxyl groups of the PGMA chains. These strong inter- and intramolecular hydrogen bonds between PGMA segments lead to a self-aggregation of R _F-PGMA evident in temperature-dependent ¹H and ¹⁹F NMR spectroscopy and dynamic light scattering measurements.