C-13 NMR谱图数据库相似检索的网上实现

本文对C-13 NMR谱图数据库相似检索的网上实现进行了研究。文章介绍了在网上实现C-13 NMR谱图数据库相似检索的方法以及提高相似检索效率的一些方法。

Zn_4B_6O_(13)∶Ce~(3+),Tb~(3+)的合成与发光

高温固相扩散方法首次合成了Zn4 B6 O1 3:Ce3+ ,Tb3+ 光致发光材料。通过XRD分析获得晶胞参数 :a =0 7472nm ,V =0 .4172nm3,为立方晶系。研究Ce3+ 和Ce3+ ,Tb3+ 在Zn4 B6 O1 3中的激发和发射光谱 ,发现Ce3+ 在Zn4 B6 O1 3中的激发和发射带比Ce3+ 在其他基质中红移2 3 8～ 4.94KK ,Ce3+ 的发射带与Tb3+ 的 7F6 → 5G2 ,5D1 ,5H7吸收带有很好的重叠 ,使Ce3+ 对Tb3+ 有良好的敏化作用。Ce3+ ,Tb3+ 在基质中的能量传递机理为 :Ce3+ →Ce3+ 和Ce3+ →Tb3+ 之间的偶极子—偶极子的电多级相互作用的共振传递机理。色坐标为 :x =0 2 81,y =0 .619。SEM摄取产物的晶貌 ,颗粒均匀 ,平均粒度为 0 .2 3 μm ,接近纳米级。

双-Keggin型四元杂多化合物[Nd(SiMo_7W_4O_(39))_2]~(13-)多层膜在化学修饰玻碳电极上的组装及电催化

报道双－Ｋｅｇｇｉｎ型四元杂多化合物Ｋ１０Ｈ３［Ｎｄ（ＳｉＭｏ７Ｗ４Ｏ３９）２］ＸＨ２Ｏ（简称［Ｎｄ（ＳｉＭｏ７Ｗ４）２］１３－）聚合物的交替组装多层膜在４－氨基苯甲酸修饰玻碳电极上的制备及其电化学特性。各层的循环伏安行为证明膜的均匀增长，峰电流随层数的增加而增加。与溶液中的电化学行为相比，位于多层膜中的杂多化合物的氧化还原特征峰随着多层膜层数的增加，具有一定程度的形变。该电极具有较高的稳定性。并讨论了ｐＨ对其氧化还原行为的影响，考察了该多层膜修饰电极对ＢｒＯ３－、ＨＮＯ２和Ｈ２Ｏ２等的电催化性能。

C-13 NMR study of ethylene/propylene/octene-1 terpolymers synthesized with TiCl4/MgCl2/i-Bu3Al as the catalyst

The theory of chemical shift effect of substituent was applied to the assignment of the C-13 NMR spectra of the ethylene/propylene and ethylene/octene-1 copolymers. Using the parameters derived above and the DEFT technique, we then entirely assigned the C-13 NMR spectra of the ethylene/propylene/octene(-1) terpolymers synthesized in the presence of the same heterogeneous supported Ziegler-Natta catalyst, TiCl4/MgCl2/i-Bu3Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene-1 terpolymers.

Carbon-13 nuclear magnetic resonance spectrum simulation of pyridines and quinolines

Artificial neural network (ANN) and multiple linear regression (MLR) were used for the simulation of C-13 NMR chemical shifts of 118 central carbon atoms in 18 pyridines and quinolines. The electronic and geometric features were calculated to describe the environments of the central carbon atom. The results provided by ANN method were better than that achieved by MLR.

Preparation of borates doped with divalent rare earth ions (RE2+) in air and spectroscopy of divalent rare earth ions (RE2+ = Sm, Eu, Tm, Yb)

The spectroscopic feature of divalent Sm2+, Eu2+, Tm2+ and Yb2+ is discussed in this paper. Especially the spectroscopic properties of some berates containing tetrahedral BO4 group such as SrB4O7, SrB6O10 and BaB8O13 doped with these divalent ions are reported. When the divalent alkaline earth ion in these berates is replaced partially by the above trivalent rare earth ion, the charge carried in the produced defects can be used as reductant to reduce the doped rare earth ion into divalent state at high temperature even in air. Therefore, a convenient and safe method is provided to prepared phosphors doped with these divalent rare earths.

层状复合氧化物La_4BaCu_(5-x)M_xO_(13+λ)的制备、表征及对CO还原NO的活性

采用柠檬酸爆炸法合成了系列层状钙钛矿型复合氧化物Ｌａ４ＢａＣｕ５ － ｘＭｘＯ１３＋ λ（Ｍ＝ Ｍｎ，Ｃｏ； ｘ＝ ０ ～５） 催化剂． 用ＴＰＤ，ＴＰＲ 和化学分析法对催化剂进行了表征，考察了催化剂在ＣＯ还原ＮＯ 中的催化活性．结果表明，掺杂Ｍｎ，Ｃｏ 后催化剂中的活性氧含量及氧化还原性质发生了变化． 掺杂少量Ｍｎ，Ｃｏ 可使催化剂在ＣＯ 还原ＮＯ中的催化活性明显提高，且掺杂Ｃｏ 的样品比掺杂Ｍｎ 的样品活性提高更明显．这是由于ＣｕＭｎ 与ＣｕＣｏ 之间的协同作用不同导致的结果.

吡啶和喹啉类化合物的碳-13核磁共振波谱模拟

运用多元回归分析和人工神经网法对１８个吡啶和喹啉类化合物的１１８个化学位移进行计算机模拟，并应用碳原子的空间和电子结构特征来表征其所处的化学环境，从而获得了比较好的相关模型。波谱模拟技术对辅助有机化合物结构解析和化学位移的确认是十分有用的工具。

用多元回归方法模拟烷烃的碳-13化学位移

用多元回归方法对 59个直链或支链烷烃化合物进行碳 - 1 3NMR波谱模拟。在这个实验中提取了分子连接性指数和几何参数 ,取得了很好的效果。

环己烷~(13)C NMR化学位移的预测

通过计算机辅助方法对1 3 CNMR化学位移进行预测 .这个方法包括分子拓扑指数和几何参数特征值的计算及对所选特征进行的变量压缩 ,并对所选共振碳的化学位移与其提取的特征进行多元回归分析 ,从而得出其相关数学模型 .本文预测了环己烷中 45个仲碳原子的1 3 C化学位移 ,其标准误差约为 1 .4ppm.

醛酮类化合物的~(13)C核磁共振波谱模拟

为饱和醛酮类化合物的1 3C核磁共振波谱模拟 .根据该类化合物的特点 ,提取了分子的拓扑特征 ,几何特征及电子特征 .应用变量最优子集回归法进行了变量的选择 ,并用这些变量构造了回归模型 .交叉验证的结果表明 ,所得数学模型比较稳定 ,并得到了较好的预测结果

在空气下制备掺二价稀土的硼酸盐及二价稀土离子(RE~(2+)=Sm,Eu,Tm,Yb)的光谱特征

本文讨论了Sm2 + 、Eu2 + 、Tm2 + 、Yb2 + 等二价稀土离子的光谱特征 ,特别是在一些含四面体硼酸根的硼酸盐如SrB4 O7、SrB6 O10 和BaB8O13中它们的光谱性质。当以三价稀土离子取代化合物中的二价碱土离子时 ,利用不等价取代而产生的缺陷所带的电荷 ,可在高温的空气下使上述的稀土离子还原成二价 ,不需加入化学还原剂 ,从而提出了一个简便、安全的制备含二价稀土离子发光材料的方法

Tb~(3+)在YAG中的发光及Tb~(3+)与Tm~(3 +)间的能量传递

采用溶胶 -凝胶方法合成了系列化合物 (Y1 -x- yTbxTmy) 3Al5O1 2 ,研究了Tb3+在该化合物中的发光及其浓度对发光性质的影响 ,以及Tb3+与Tm3+间的能量传递现象。

Prediction of C-13-nuclear magnetic resonance chemical shifts for aliphatic amines

Prediction of C-13-nuclear magnetic resonance chemical shifts for aliphatic amines is performed. The topological, geological and electronic descriptors are generated. To reduce the variables, the best subsets of the descriptors are obtained by using leaps-and-bounds regression analysis. The model is achieved using multiple regression with satisfactory results.

Electrochemical and in situ spectroelectrochemical behavior of 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H(2)OHTTAP) and (Zn(II)OHTTAP)

The characterization of free base porphyrin 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H(2)OHTTAP) and its zinc(II) complexes [Zn(II)OHTTAP] containing eight thioether groups at the beta -pyrrole positions of the macrocycle was reported. Results obtained by cyclic voltammetry and differential pulse voltammetry indicated a five-electron reduction in five steps for each complex. They were oxidized in two single-electron-transfer steps to yield pi -cation radicals and dications and reduced in three single-electron-transfer steps to yield pi -anion radicals, dianions and trianions, respectively. The redox property of H(2)OHTTAP was unusual as compared to porphyrins (PPs) and phthalocyanines (Pcs). Each process was monitored by in situ thin-layer spectroelectrochemistry, which indicated that only the Ligand was electroactive. The existence of the eight hexylthio groups was responsible for the intrastack interactions and enhanced intracolumnar and intercolumnar electron motions, resulting in improved conductivity. Copyright (C) 2001 John Wiley & Sons, Ltd.