Fabrication of ultrathin films with large third-order nonlinear optical properties.

An ultrathin composite film containing anionic Ag-His complexes (His: L-Histidine) and oppositely charged BH-PPV was fabricated by means of the electrostatic layer-by-layer self-assembly technique. UV/Vis spectra showed a continuous deposition process of Ag-His complexes and BH-PPV. The film structure was characterized by using small-angle X-ray diffraction, AFM, and SEM. The nonlinear optical properties of the ultrathin film were studied by using the Z-scan technique with a laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited a strong nonlinear saturated absorption, with an alpha2 value of -3.9 x 10(-5) mW(-1) and a self-defocusing effect with an n2 value of -4.78 x 10 (-12) m2W(-1).     

Cyano-bridged CuII-MV (M = Mo, W) bimetallic layered complexes exhibiting novel honeycomblike structures

Self-assembly of a new precursor [Cu(L)](ClO4)2 (1) (L = macrocyclic ligand) with octacyanometalates [M(CN)8]3- (M = Mo, W) produced two-dimensional cyano-bridged Cu(II)-M(V) bimetallic assemblies [Cu(L)]3n[M(CN)8]2n.6nH2O [M = Mo (2), W (3)] with novel honeycomblike structures, characterized by spectroscopic data, single-crystal X-ray diffraction studies, and magnetic measurements. The crystallographic determination reveals that compounds 2 and 3 are isostructural and crystallize in the triclinic system (P). The Cu atom in a distorted octahedral environment experiences a tetragonal elongation of apical nitrogen atoms exhibiting average Cu-Nax lengths of 2.566 Angstroms for 2 and 2.593 Angstroms for 3, which accounts for the Jahn-Teller effect of a Cu(II) ion. The Cu-NC angles are magnetically important, ranging from 135.7 to 159.2 degrees. Three types of L in the crystal lattice are observed, which are dependent on the relative positions of the pendant hydroxyl groups with respect to the CuN4 basal plane. The positions are correlated with hydrogen bonding of OH groups to neighboring atoms. The magnetic data indicate that ferromagnetic and antiferromagnetic interactions between Cu(II) and M(V) through the CN linkage coexist.     

C9‐Iridoids from Scrophularia buergeriana

Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis.     

Microwave-accelerated derivatization processes for the determination of phenolic acids by gas chromatography-mass spectrometry

A rapid method for the derivatization of phenolic antioxidants using microwave irradiation has been developed. Six antioxidatively active phenolic components of wines and fruits, namely gallic acid, gentisic acid, vanillic acid, caffeic acid, ferulic acid and p-coumaric acid were used in the model study. The solution of phenolic acids was evaporated to dryness on a rotary evaporator followed by further drying under microwave irradiation (600 W, 30 s). The resultant residue was dissolved in pyridene and treated with bis(trimethylsilyl)acetamide while irradiated by microwave using high power for 30 s. Controlled reaction was carried out employing bis(trimethylsilyl)trifluoroacetamide under conventional heating for 30 min. The trimethylsilyl derivatives were identified and quantified on a gas chromatography/mass selective detector. The mass spectral fragmentation patterns of the derivatives obtained by microwave irradiation were identical to those prepared by heating. The yields of microwave-assisted silylation were comparable to those from conventional heating. The rsd were less than 8% for six replicates. The linearity in wine matrix was nearly perfect. This method is a useful protocol to examine the phenolic constituents in wines and agricultural products.     

Raman scattering from Pt(CN)42− adsorbed on Pt colloids

Raman scattering from Pt(CN)₄^2? adsorbed on Pt colloids (average diameter of 16 A) is compared with the Raman signal from the same amount of Pt(CN)₄^2? in solution. The wavelength dependence of the adsorbate Raman intensity is measured from 308 to 647 nm and compared with a Lorenz/Mie calculation of the enhancement factor for the electromagnetic field intensity on the surface of a Pt sphere as a function of sphere radius and incident wavelength.     

Pyrolysis of poly(vinyl chloride)

A pyrolysis–gas chromatography–mass spectrometric technique has been developed to study the thermal degradation of poly(vinyl chlorides) polymerized at different temperatures. Hydrogen chloride and benzene evolution during successive stages of pyrolysis have been quantitatively determined and correlated to the tacticity and molecular weight of the polymer. It was found that lowering the temperature of polymerization and molecular weight depresses benzene evolution and increases char weight but does not affect the HCl yield. It is suggested that the syndiotactic trans microstructure favored at low temperature of polymerization yields polyenes which cannot cyclize to form benzene. As the molecular weight decreases, the increase in number of vinyl chain ends facilitates pyrolytic crosslinking and char formation.     

胺、醇、醚类化合物电离能的自相关拓扑研究

原子的染色序数 fi 定义为 :fi=gi·xi,式中 gi 为原子i在分子中的序数 ,xi 为其染色系数 .基于fi 建立改进的原子序数自相关拓扑指数mF ,其中的1F对烷烃及其衍生物具有良好的结构选择性 .使用第一电离能 (Ip)与0 F ,1F的数量关系模型对 32种脂肪族胺、醇、醚进行估算、预测 ,结果令人满意     

HCN及其氢加成物分子间氢键问题的量子化学研究

采用量子化学(MNDO、CNDO/2)方法,探讨了HCN、H_2CNH和H_3CNH_2分子间的N…H-C氢键的构成。计算表明:HCN-HCN分子间氢键作用较强,支持了实验结果。HCN及其氢加成物H_2CNH、H_3CNH_2等分子间的氢键作用依次减弱,其随C≡N、C=N、C-N的差异而变化,碳氮链中氮原子的作用是构成N…H-C型氢键的一个决定性因素。     

甲苯甲醇侧链烷基化反应中沸石催化剂酸碱中心的作用Ⅱ．改性的X型和双组分改性的X／ZSM－5双沸石催化剂

制备了改性的ｘ型和ｘ／ＺＳＭ－５型沸石催化剂，并对其进行了评价和ＴＰＤ、ＥＳＣＡ表征，将实验结果进行了关联。结果表明，采用ＫＯＨ，Ｈ＿３ＢＯ＿３和碱土金属化合物等作为改性剂，可以调变沸石催化剂的酸碱中心，其中碱酸密度比为０．５３９的ＫＸ（Ｂ＿３）·ＫＺＳＭ－５（Ｃａ）催化剂，能显著提高甲苯、甲醇侧链烷基化制取苯乙烯反应的选择性和收率。井根据对实验结果的分析，初步探讨了甲苯、甲醇侧链烷基化反应的机理。     

红厚壳属植物化学成份及药理活性研究进展

综述了近年来对红厚壳属植物中的化学成分及药理活性研究，重点讨论了18种 红厚壳属植物中Zhao吨酮类，香豆素类，黄酮类和萜类的化学成分，并讨论了它们 的药理活性。