Solid-state magnetic resonance studies of polyaniline as a radical scavenger

The first detailed study of polyaniline (PANI) and reduced PANI (R-PANI) before and after reaction with the stable organic free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) by using solidstate¹³C CP MAS (cross-polarization magic-angle spinning), NQS (nonquaternary suppressed) and CPPI (cross-polarization phase inversion) nuclear magnetic resonance techniques is reported. These techniques reveal relatively subtle structural changes that occur upon reaction with DPPH free radicals and confirm the radical scavenging ability of PANI. The integrated intensity of the PANI CP MAS spectrum after reaction with DPPH is about 8% larger than that of PANI and this cannot be explained by an oxidation process alone. The increase is attributed to a decrease in the polaron concentration in the polymer, which is consistent with electron paramagnetic resonance (EPR) data that show a decrease of the EPR signal intensity after reaction of chemically synthesized PANI with DPPH.     

Fast proton spin-lattice relaxation time in the rotating frame during the application of time averaged precession frequency

A relatively rapid phase alternation of the effective field in the time averaged precession frequency (TAPF) sequence results in averaging of the proton RF spin-lock field. The spin-locking of the proton magnetization becomes less efficient and thus shortens T(1rho)(H), the proton spin-lattice relaxation time in the rotating frame. The relaxation time also depends on the ratio of tau(1) and tau(2) intervals i.e. tau(1)/tau(2) and not only on the number of tau(c)=tau(1)+tau(2) blocks, i.e. the number of the phase transients. Experiments are performed on solid samples of ferrocene and glycine and for some time intervals, T(1rho)(H) is shortened by factors of 9-100 compared to the relaxation times obtained in the standard experiment.     

电感耦合等离子体原子发射光谱法测定马奶酒中的多种元素

电感耦合等离子体原子发射光谱法测定马奶酒中的多种元素嘎日迪,乌地（内蒙古师范大学化学系,配位化学研究所,呼和浩特,０１００２２）关键词电感耦合等离子体原子发射光谱,马奶酒,微量金属元素蒙古民族喜爱的传统饮料──马奶酒（蒙语“策格”）是用鲜马奶为原料发...     

抗阿尔兹海默症藏药三味豆蔻汤的化学成分分析研究

三味豆蔻汤作为藏药的经典方剂,由药材豆蔻、香旱芹、荜茇和牦牛奶熬煮制成,其对阿尔兹海默症(Alzheimer's disease,AD)具有一定的治疗作用.该方剂化学成分复杂且极性、挥发性差异大,相关的物质基础研究较少.该研究分别采用气相色谱-质谱(GC-MS)、超高效液相色谱-高分辨串联质谱(UPLC-HRMS/MS...     

加速度环境下微槽流动与传热特性

航空电子设备在加速度环境下工作时,采用液体工质进行散热的电子设备的散热性能将受到加速度的影响。本文采用有限体积法对加速度环境下矩形微槽中体积浓度30%的乙二醇水溶液的流动和传热特性进行了系统研究。考察了加速度大小和方向对微槽中流动与传热特性的影响,以及加速度环境对不同微槽结构和工质流量下流动与传热特性的影响。研究表明,与不考虑加速度影响时相比,在开始的瞬间,微槽传热性能大幅降低,流动阻力系数急剧上升,     

基于SEM的我国重要城市现代化水平综合评价模型研究

基于结构方程(SEM)理论,以2008年统计数据为样本对影响城市现代化的测量指标进行了一阶、二阶验证性因素分析,得到了结构方程模型.并以测量指标在因子上的负荷、路径系数为基础构建权重,建立了城市现代化水平综合评价模型.对我国重要城市(直辖市、主要省会城市)现代化水平程度进行了相对评价,得到较为满意的结果.     

Structural and Infrared Spectroscopic Studies of Some Adducts of Divalent Metal Dihalides (MX2, M = Zn,Cd; X = CI,Br, I) with Variously Hindered Monodentate Nitrogen (Pyridine) Base Ligands (L = Pyridine, 2‐Methylpyridine,and Quinoline) of 1:2 Stoichiometry

Single crystal X‐ray structure determinations are described for a number of adducts of 1:2 MX₂:L stoichiometry, [M = divalent metal (Zn, Cd); X = halide (Cl, Br, I), L = (variously hindered) monodentate nitrogen (pyridine) base: py = pyridine, 2‐mpy = 2‐methylpyridine, quin = quinoline]: [(2‐mpy)₂ZnX₂] (X = Cl, Br) (isotypic, triclinic P , a ≈? 7.9₆, b ≈? 8.7, c ≈? 11.4 Å, α ≈? 86, β ≈? 79.3, γ ≈? 67°, Z = 2), [(2‐mpy)₂ZnI₂], [(quin)₂ZnX₂] (X = Br) (isotypic with the previously determined chloride, X = Cl, triclinic, P , a ≈? 8.7, b ≈? 9.6, c ≈? 11.1 Å, α ≈? 81, β ≈? 73, γ ≈? 72°, Z = 2); [(quin)₂ZnI₂]; [(2‐mpy)₂CdX₂], X = Br {isotypic with [(2‐mpy)₂ZnX₂], X = Cl, Br (above)}, X = I {isotypic with [(2‐mpy)₂ZnI₂] (above)}; [(quin)₂CdI₂]. A single molecule, with a four‐coordinate quasi‐tetrahedral metal atom, N₂MX₂, comprises the asymmetric unit of the structure in each of these. A one‐dimensional polymer is found for [(quin)₂Cd(μ‐Cl)₂]_(∞‖∞), similar to those recorded previously for CdX₂:py (1:2) (X = Cl, Br, I), the cadmium atom here lying on a 2‐axis in tetragonal space group P 2₁c, and the quin ligands coordinating trans in a six‐coordinate array about the cadmium, with successive cadmium atoms being linked by pairs of bridging chlorines. Adducts of MX₂:L (1:1) stoichiometry, defined for M = Cd: [(2,4,6‐trimethylpyridine)Cd(μ‐I)₂]_(∞‖∞) and [(quin)Cd(μ‐Br)₂]_(∞‖∞), are both infinite one‐dimensional polymers … (μ‐X)₂Cd(L)(μ‐X)₂Cd(L) … , with five‐coordinate trigonal bipyramidal cadmium atoms, the nitrogen donors being equatorial in the coordination spheres. The far‐IR spectra of [L₂MX₂] (L = py, 2‐mpy, quin; M = Zn, Cd; X = Cl, Br, I) are assigned and discussed in relation to the structures of the complexes.     

Mechanochemical synthesis in copper(II) halide/pyridine systems: single crystal X-ray diffraction and IR spectroscopic studies

Whereas complexes of divalent metal halides (X = Cl, Br, I) with/from pyridine commonly crystallise as trans-[M(py)(4)X(2)]·2py, M on a site of 222 symmetry in space group Ccca, true for CuCl(2) and CuBr(2) in particular, the copper(II) iodide adduct is of the form [Cu(py)(4)I]I·2py, Cu on a site of mm2 symmetry in space group Cmcm, and five-coordinate (square-pyramidal), the same cationic species also being found in 2[Cu(py)(4)I](I(3))·[(py)(2)Cu(μ-I)(2)Cu(py)(2)] (structurally defined). Bromide or N-thiocyanate may be substituted for the unbound iodide ion in the solvated salt, resulting in complexes which crystallize in space group Ccca, but with both anions and the metal atom disordered. In [Cu(py)(4)(I(3))(2)], a pair of long Cu···I contacts approach a square-planar Cu(py)(4) array. Assignments of the ν(CuN) and ν(CuX) (X = Br, I, SCN) bands in the far-IR spectra are made, the latter with the aid of analogous assignments for [Cu(py)(2)X(2)] (X = Cl, Br), which show a dependence of ν(CuX) on the Cu-X bond length that is very similar to that determined previously for copper(i) halide complexes. The structure of the adventitious complex [(trans-)(H(2)O)(py)(4)CuClCu(py)(4)](I(3))(3)·H(2)O is also recorded, with six- and five-coordinate copper atoms; rational synthesis provides [{Cu(py)(4)}(2)(μ-Cl)](I(3))(3)·H(2)O with one water molecule less. In [{Cu(py)(4)Cl}((∞|∞))](I(3))·3py, square pyramidal [Cu(py)(4)Cl](+) cations, assisted by Cl···Cu interactions, stack to give rise to infinite polymeric strings. Several of these compounds were prepared mechanochemically, illustrating the applicability of this method to syntheses involving redox reactions as well as to complex syntheses involving up to five components. The totality of results demonstrates that the [Cu(II)(py)(4)] entity can be stabilized in an unexpectedly diverse range of mononuclear and multinuclear complexes through the presence of lattice pyridine molecules, the bulky triiodide ion, or a combination of both.     

Chemical synthesis and characterization of poly(aniline‐co‐ethyl 3‐aminobenzoate) copolymers

Copolymers of aniline and ethyl 3‐aminobenzoate (3EAB) were synthesized by chemical polymerization in several mole ratios of aniline to functionalized aniline, and their physicochemical properties were compared to those of poly(aniline‐co‐3‐aminobenzoic acid) (3ABAPANI) copolymers. The copolymers were characterized with UV–vis, FTIR, Raman, SEM, EPR, and solid‐state NMR spectroscopy, elemental analysis, and conductivity measurements. The influence of the carboxylic acid and ester group ring substituents on the copolymers was investigated. The spectroscopic studies confirmed incorporation of 3ABA or 3EAB units in the copolymers and hence the presence of C?O group in the copolymer chains. The conductivity and EPR signals both decreased with increasing 3EAB content of the copolymers emeraldine salt (ES) form. The conductivity of the ES form of 3ABAPANI was found to be high (1.4 × 10^?1 S cm^?1) compared with the conductivity (10^?2–10^?3 S cm^?1) of 3EABPANI (ES) copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1339–1347, 2010