[{Cu(phen)2}(μ‐malato){Cu(phen)(NO3)}](NO3)·4H2O: malate acting as a tetra­dentate and dibridging ligand in a dinuclear copper complex

The crystal structure of the title compound, μ‐2‐hydroxy­butane­dioato‐1κ²O⁴,O^4′:2κ³O¹,O²,O⁴‐nitrato‐2κO‐tris­(1,10‐phen­anthroline)‐1κ⁴N,N′;2κ²N,N′‐dicopper(II) nitrate tetra­hydrate, [Cu₂(C₄H₃O₅)(NO₃)(C₁₂H₈N₂)₃](NO₃)·4H₂O, contains an unsymmetrical dinuclear copper complex with Cu(phen)₂ and Cu(phen)(NO₃) moieties (phen is 1,10‐phenanthroline) bridged by a malate (2‐hydroxy­butane­dioate) ligand, which acts as a double‐bridging and tetra­dentate ligand. As a result of this double‐bridging action, especially the direct coordination of the O atom of one carboxyl­ate group of malate to the two Cu atoms, the Cu⋯Cu distance is only 4.199 (1) Å and the two phen planes are roughly parallel [the shortest inter­planar distance is 3.28 (1) Å], exhibiting an obvious intra­molecular π–π stacking inter­action.     

catena‐Poly[[tetra­aqua­manganese(II)]‐μ‐4‐(carboxyl­ato­methyl­sulfanyl)­phenoxy­acetato]

The title compound, [Mn(C₁₀H₈O₅S)(H₂O)₄]_n, a one‐dimensional manganese(II) complex comprising helical chains bridged by 4‐(carboxylatomethylsulfanyl)phenoxyacetate ligands has been characterized by single‐crystal X‐ray diffraction analysis. Hydrogen‐bonding inter­actions between adjacent chains extend the complex into a three‐dimensional supra­molecular architecture.     

Xanthine Sensors Based on Anodic and Cathodic Detection of Enzymatically Generated Hydrogen Peroxide

A xanthine biosensor was fabricated by the covalent immobilization of xanthine oxidase (XO) onto a functionalized conducting polymer (Poly‐5, 2′: 5′, 2″‐terthiophine‐3‐carboxylic acid), poly‐TTCA through the formation of amide bond between carboxylic acid groups of poly‐TTCA and amine groups of enzyme. The immobilization of XO onto the conducting polymer (XO/poly‐TTCA) was characterized using cyclic voltammetry, quartz crystal microbalance (QCM), and X‐ray photoelectron spectroscopy (XPS) techniques. The direct electron transfer of the immobilized XO at poly‐TTCA was found to be quasireversible and the electron transfer rate constant was determined to be 0.73 s^?1. The biosensor efficiently detected xanthine through oxidation at +0.35 V and reduction at ?0.25 V (versus Ag/AgCl) of enzymatically generated hydrogen peroxide. Various experimental parameters, such as pH, temperature, and applied potential were optimized. The linear dynamic ranges of anodic and cathodic detections of xanthine were between 5.0×10^?6?1.0×10^?4 M and 5.0×10^?7 to 1.0×10^?4 M, respectively. The detection limits were determined to be of 1.0×10^?6 M and 9.0×10^?8 M with anodic and cathodic processes, respectively. The applicability of the biosensor was tested by detecting xanthine in blood serum and urine real samples.     

catena‐Poly[[[pyridinecopper(II)]bis[μ3‐4‐(2‐oxidobenzylideneamino)benzoato]] dimethylformamide disolvate], a polymer composed of dimeric dicopper building units

The title compound, {[Cu(C₁₄H₉NO₃)(C₅H₅N)]·C₃H₇NO}_n or {[Cu₂L₂(py)₂]·2DMF}_n [py is pyridine, L is 4‐(salicylideneamino)benzoate and DMF is dimethylformamide], is composed of dimeric dicopper [CuL(py)]₂ building units, which are interlinked into a one‐dimensional chain through the formation of Cu—O_COO bonds. The dimeric unit is centrosymmetric, containing two Cu^II atoms linked by bridging phenolate O atoms into a Cu₂O₂ plane with a chelating Cu—O bond length of 1.927 (2) Å and a bridging Cu—O bond length of 2.440 (2) Å. Interchain C—H...O and π–π stacking interactions are responsible for an extensive three‐dimensional structure in which the resulting channels are filled by DMF solvent molecules.     

Thermotropic Liquid Crystals Based on Extended 2,5‐Disubstituted‐1,3,4‐Oxadiazoles: Structure–Property Relationships,Variable‐Temperature Powder X‐ray Diffraction,and Small‐Angle X‐ray Scattering Studies

A class of extended 2,5‐disubstituted‐1,3,4‐oxadiazoles R¹‐C₆H₄‐{OC₂N₂}‐C₆H₄‐R² (R¹=R²=C₁₀H₂₁O 1 a , p‐C₁₀H₂₁O‐C₆H₄‐C?C 3 a , p‐CH₃O‐C₆H₄‐C?C 3 b ; R¹=C₁₀H₂₁O, R²=CH₃O 1 b , (CH₃)₂N 1 c ; F 1 d ; R¹=C₁₀H₂₁O‐C₆H₄‐C?C, R²=C₁₀H₂₁O 2 a , CH₃O 2 b , (CH₃)₂N 2 c , F 2 d ) were prepared, and their liquid‐crystalline properties were examined. In CH₂Cl₂ solution, these compounds displayed a room‐temperature emission with λ_max at 340–471 nm and quantum yields of 0.73–0.97. Compounds 1 d , 2 a – 2 d , and 3 a exhibited various thermotropic mesophases (monotropic, enantiotropic nematic/smectic), which were examined by polarized‐light optical microscopy and differential scanning calorimetry. Structure determination by a direct‐space approach using simulated annealing or parallel tempering of the powder X‐ray diffraction data revealed distinctive crystal‐packing arrangements for mesogenic molecules 2 b and 3 a , leading to different nematic mesophase behavior, with 2 b being monotropic and 3 a enantiotropic in the narrow temperature range of 200–210 °C. The structural transitions associated with these crystalline solids and their mesophases were studied by variable‐temperature X‐ray diffractometry. Nondestructive phase transitions (crystal‐to‐crystal, crystal‐to‐mesophase, mesophase‐to‐liquid) were observed in the diffractograms of 1 b, 1 d , 2 b, 2 d , and 3 a measured at 25–200 °C. Powder X‐ray diffraction and small‐angle X‐ray scattering data revealed that the structure of the annealed solid residue 2 b reverted to its original crystal/molecular packing when the isotropic liquid was cooled to room temperature. Structure–property relationships within these mesomorphic solids are discussed in the context of their molecular structures and intermolecular interactions.     

A Selective Cholesterol Biosensor Based on Composite Film Modified Electrode for Amperometric Detection

An amperometric cholesterol biosensor based on immobilization of cholesterol oxidase in a Prussian blue (PB)/polypyrrole (PPy) composite film on the surface of a glassy carbon electrode was fabricated. Hydrogen peroxide produced by the enzymatic reaction was catalytically reduced on the PB film electrode at 0 V with a sensitivity of 39 μA (mol/L)^?1. Cholesterol in the concentration range of 10^?5 ? 10^?4 mol/L was determined with a detection limit of 6 × 10^?7 mol/L by amperometric method. Normal coexisting compounds in the bio‐samples such as ascorbic acid and uric acid do not interfere with the determination. The excellent properties of the sensor in sensitivity and selectivity are attributed to the PB/PPy layer modified on the sensor.     

A novel three‐dimensional cadmium(II) coordination polymer incorporating 1,4‐bis­(1,2,4‐triazol‐1‐ylmethyl)­benzene and thio­cyanate

In the title complex, poly[cadmium(II)‐μ₂‐1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene‐di‐μ₂‐thio­cyanato], [Cd(NCS)₂(C₁₂H₁₂N₆)]_n, the Cd^II atom lies on an inversion centre in a distorted octa­hedral environment. Four N atoms from the thio­cyanate and 1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene (bbtz) ligands occupy the equatorial positions, and two S atoms from symmetry‐related thio­cyanate ligands occupy the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thio­cyanate bridges link the Cd^II atoms into two‐dimensional sheets containing novel 16‐membered [Cd₄(μ‐NCS‐N:S)₄] rings. The bbtz ligands further link these two‐dimensional sheets into an unprecedented covalent three‐dimensional network for the cadmium–thio­cyanate system.     

过氧化氢与N—甲基苯胺盐酸盐引发体系的研究

在水介质中,研究了新型的过氧化氢/N-甲基苯胺盐酸盐引发体系对 AM 与 PVA 的接枝共聚。产物经紫外光谱、红外光谱和 ~1H-核磁共振进行表征,并提出了引发机理。     

Particle interactions in electrophoresis: I. Motion of two spheres along their line of centers

The electrophoretic motion of two charged colloidal spheres with very thin electrical double layers in a constant applied electric field along their line of centers is considered. The particles may differ in radius and in zeta potential at the surface. The electrostatic and hydrodynamic governing equations are solved in the quasi-steady situation using bipolar coordinates and the electrophoretic velocities of particles are calculated for various cases. The interaction effect between particles can be very significant when the distance between particle surfaces gets close to zero. The particle with smaller zeta potential is speeded up by the motion of the other, which is retarded at the same time by the motion of the former one, if the two spheres have unequal zeta potentials of the same electrical sign. For two particles of different signs in zeta potential, motions of both are hindered by each other. The influence of the interaction between particles in general is stronger on the smaller one than on the larger one. For the special case of two electrophoretic spheres with identical zeta potentials, there is no particle interaction for all particle sizes and separations.     

Studies on Liquid/liquid Extraction of Copper Ion with Room Temperature Ionic Liquid

Room temperature ionic liquids are regarded as “Green solvents” for their nonvolatile and thermally stable properties. They are employed to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. In this work, a water immiscible room temperature ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate [C₄mim][PF₆], was used as an alternative solvent for liquid/liquid extraction of copper ions. Metal chelators, including dithizone, 8‐hydroxyquinoline, and 1‐(2‐pyridylazo)‐2‐naphthol, were employed to form neutral metal‐chelate complexes with copper ions so that copper ions were extracted from aqueous solution into [C₄mim][PF₆]. The parameters that affect the extraction of copper ions with this biphasic system were investigated. The extraction behavior in this novel biphasic system is shown to be consistent with that of traditional solvents. For example, the extraction with this biphasic system is strongly pH dependent. So, the extraction efficiency of coppers ion from an aqueous phase can be manipulated by tailoring the pH value of the extraction system. Hence, the extraction, separation and preconcentraction of copper ions can be accomplished by controlling the pH value of the extraction system. It appears that the use of ionic liquid as an alternate solvent system in liquid/liquid extraction of copper ions is very promising.