有机银溶胶的吸收光谱和表面增强Raman光谱研究

研究了2-氨基苯并咪唑(BIMNH₂)、LiCl、NaOEt对Ag/EtOH溶胶吸收光谱和表面增强Raman散射(SERS)光谱的影响。结果表明,少量的吸附分子BIMNH₂、LiCl、NaOEt均能改变溶胶聚集状态,从而影响其吸收光谱和SERS效应。此外,Cl^-还可与Ag、BIMNH₂形成表面络合物而增强SERS效应。对Ag溶胶体系SERS光谱的溶剂效应也作了初步研究。     

酸性染料在银溶胶上吸附状态的表面增强拉曼光谱研究

表面增强拉曼光谱技术 (SERS)能从分子水平上直接提供表面分子结构和动态过程等重要信息 ,被广泛地用于各种物质在金、银、铜等贵金属表面的吸附机理研究 ;本文通过对不同浓度的酸性黑和酸性红在银溶胶上的表面增强拉曼光谱的研究 ,探讨了浓度对其在银溶胶表面吸附状态的影响 ;结果表明 ,酸性黑和酸性红均为5×10-4 mol/L时 ,在银溶胶表面上发生吸附状态改变 ,并形成一个满单分子层 ,表面拉曼信号最强。     

C70分子吸附于铜表面的增强拉曼光谱研究

报道了C70分子吸附于铜表面的增强拉曼光谱.通过与正常拉曼光谱以及银表面SERS谱的比较发现,C70分子与铜表面之间的吸附属于物理吸附,增强机制主要是电磁增强.C70分子在银表面上的吸附状态与铜表面上的不同,这导致了两者特征峰谱线强度分布存在差异.以C60的振动模式为参考,推断出C70分子在2种金属表面上的吸附状态可能分别处于使碳笼的挤压振动模接近于“平躺”和“竖直”的2种状态.     

异烟酸在银溶胶上的表面增强喇曼散射及影响因素

本文研究了异烟酸吸附在银溶胶表面的表面增强喇曼散射(SERS)光谱以及卤素离子、溶液pH值及溶液浓度对异烟酸SERS光谱的影响。文章提出了离子在银溶胶表面的吸附方式,即主要以—COO~-端吸附于银溶胶表面。最后,对所述实验现象作了定性讨论。     

电解质对纳米银胶水溶液光谱行为的影响

纳米粒子因为具有量子尺寸效应和表面效应等特性而显示出体相材料不具备的各种性质[1] .贵金属纳米材料因其特有的光电磁性质、催化特性以及在微电子学领域中的潜在应用前景而成为纳米材料科学领域中的热点之一 [2～ 4 ] .纳米银胶粒子的表面性质对材料的性质和应用具有重要影响 .常用谱学手段研究纳米银胶的表面特性[5～ 7] .纳米银胶颗粒表面电子云的等离子体共振效应导致了银胶在紫外 -可见光谱上的特征吸收 ,而且吸收峰的峰形会受纳米银胶粒子的大小、分散溶剂及表面吸附分子等因素的影响 [8,9] .Arnim Henglein等 [9～ 11]系统研究了…     

尿嘧啶在银电极表面吸附状态的研究

综合分析了尿嘧啶在银电极表面不同条件的表面增强激光Ｒａｍａｎ光谱（ＳＥＲＳ）,利用扩展的Ｈüｃｋｅｌ分子轨道法（ＥＨＭＯ）对尿嘧啶分子在银电极表面的吸附状态进行了计算．结果表明：最稳定的吸附构型能较成功地阐明尿嘧啶吸附在银表面的ＳＥＲＳ谱;尿嘧啶在银表面主要是以Ｎ（３）去质子化的形式吸附;尿嘧啶在银表面的吸附取向是由其浓度和银表面电位共同决定;在较低浓度和较高电位时,Ｎ（３）去质子化的尿嘧啶离子在银表面主要是通过Ｃ（２）及整个嘧啶环上的π电子体系与银表面的相互作用平躺地吸附;在较高浓度和较低电位时,吸附取向发生改变,即主要是通过Ｎ（３）与Ｏ（１０）以及Ｎ（３）与Ｏ（８）垂直地共同吸附在银表面上     

阴离子吸附对Ag溶胶光学性质和表面增强拉曼散射的影响

本文研究了吸附几种不同阴离子(CO~3^2-, OH^-, I^-, Br^-, Cl^-)的Ag溶胶的吸光性质和表面增强拉曼散射(SERS)效应。研究发现, 亲核能力较强的阴离子在胶粒表面有较强的吸附, 并能有效降低胶粒表层的自由电子密度, 从而使Ag溶胶的吸收峰向长波方向移动; 溶胶中产生SERS的机理是阴离子在Ag胶粒表面上的化学吸附, SERS的强度随吸附覆盖度的增大而增大。     

银纳米粒子表面油酸盐吸附的分子模拟

采用分子力学方法模拟了油酸盐分子在银纳米粒子(111)表面的两种主要吸附形态: 双键吸附和羧基吸附, 计算了不同溶剂环境中油酸盐分子的吸附能和振动频率. 结果表明: 作为银纳米粒子保护剂的油酸盐能够稳定地存在于极性和非极性溶剂环境中, 与银表面的作用方式随溶剂极性的改变而改变, 水相中以双键吸附为主, 而在有机相中主要是羧基吸附. 这与红外光谱实验的推论基本吻合. 从而在分子水平上为实验结果提供了有价值的理论支持和微观信息.     

N,N'-二乙基喹啉菁染料分子吸附在溴化银溶胶上的表面增强喇曼散射

N,N'-二乙基喹啉菁染料分子吸附在硫敏化过的溴化银溶胶上产生强的表面增强喇曼散射,这种散射实际上是在直晒银上产生的。N,N'-二乙基喹啉菁染料分子吸附在硫敏化过的溴化银溶胶和银溶胶上的喇曼谱基本相似。而未经硫敏化的溴化银溶胶和经硫敏化后再被高硫酸钠氧化的溴化银溶胶中测不到N,N'-二乙基喹啉菁染料的表面增强喇曼信号。本实验进一步表明,表面增强喇曼散射方法可以用于感光机理的研究。     

含氨基酸席夫碱的5-氟尿嘧啶类衍生物在银溶胶上的吸附状态研究

合成了三种含氨基酸席夫碱的5-氟尿嘧啶类衍生物,用元素分析和1H NMR表征了它们的结构;用拉曼光谱（RS）和表面增强拉曼光谱（SERS）研究目标化合物在银溶胶上的吸附状态,推测其SERS增强机理.结果表明：在银溶胶表面上,羧基氧原子与银形成化学建,苯环是稍微倾斜地吸附在银胶面上,其它部分则平躺吸附于银溶胶表面.     

Relation between sers intensity and electronic structures for a series of compounds C6H5(CH2)n COOH (n = 0, 1, 2)

In this paper, the SERS spectra of a series of compounds C₆H₅(CH₂)_nCOOH (n = 0, 1, 2) adsorbed on colloidal silver are recorded and compared with each other. The relation between the SERS intensities and the electronic structures of the compounds are discussed. The results support the molecular enhancement mechanism on SERS, especially the charge transfer idea.     

Four unit linking groups IV. Liquid crystals of positive dielectric anisotropy

Three separate series of new materials of weak to strongly positive dielectric anisotropy have been prepared. Each series contains four sub-sets of materials each incorporating a different four unit linking group (i.e., C₄H₈, C₄H₆, C₃H₆O and C₃H₄O) and the same series of end groups (i.e. F, CN and OCF₃) in various substitution patterns. The synthesis and liquid crystal transition temperatures of these novel substances are described and compared with those of the corresponding materials incorporating standard central linkages (i.e.-, C₂H₄, CH₂O, COO). The effect of an additional trans carbon-carbon double bond in the terminal alkyl chain and in the central linking unit has also been studied.     

系列Sm3+配合物的合成、结构及光物理性能

采用水热方法合成了4种Sm³⁺配合物, 即{[SmZn(2,5-pdc)₂(tp)_0.5(H₂O)]·2H₂O}_n(1), [Sm₂Zn₂(C₆H₅COO)₁₀(Imh)₂(H₂O)₂](2), {[Sm₂(NO₂C₆H₄COO)₆(H₂O)₄]·H₂O}_n(3)和{[SmN(CH₂COO)₃(H₂O)₂]·H₂O}_n(4)[2,5-pdc=2,5-吡啶二羧酸根, tp=对苯二甲酸根, C₆H₅COO=苯甲酸根, Imh=咪唑, NO₂C₆H₄COO=对硝基苯甲酸根, N(CH₂COO)₃=氨三乙酸根]. 通过单晶X射线衍射确定了其晶体结构. 在室温下测定了其红外光谱、 紫外-可见-近红外光谱以及在近红外区和可见区的发射光谱. 结果表明, 4种配合物在近红外区或可见区均出现Sm³⁺离子的特征发射. 这是形成配合物后, Zn-配体部分和配体对Sm³⁺离子发光的敏化作用所致. 此外, 讨论了不同有机配体或d过渡金属离子对Sm³⁺离子发光的影响, 并分析了配合物中Sm³⁺离子的近红外发射带位移、 劈裂和加宽的原因.     

Synthesis and structural characterization of mixed ligand η-2-hydroxyacetophenone complexes of cobalt(III)

A tridentate Schiff base ligand [(CH₃)₂NCH₂CH₂N=C(CH₃)C₆H₄OH)] (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine. This ligand forms the neutral complexes [Co(L)(N₃){o-(CH₃C=O)C₆H₄O}] (1) and [Co(L)(SCN){o-(CH₃C=O)C₆H₄O}]·1/2H₂O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2. The complexes have been characterized by spectroscopic and crystallographic methods. The coordination geometry around Co(III) in both the complexes is distorted octahedral with one tridentate ligand L, one bidentate 2-hydroxyacetophenone and one monodentate azide for 1 and thiocyanate for 2. The azide and thiocyanate ligands in the two complexes occupy different positions relative to the coordination sites of L.     

An FTIR study of mechanisms for the HO radical initiated oxidation of C2H4 in the presence of NO: detection of glycolaldehyde

Using the long-path FTIR method, glycolaldehyde, CH₂(OH)CHO, was detected among the products in photolysis of mixtures containing C₂H₄, NO and RONO (R = alkyl group) at ppm concentrations in air. The results suggest the occurrence of both unimolecular dissociation and O₂ reaction of an oxy-radical, CH₂(OH)CH₂O, formed in the HO-initiated oxidation of C₂H₄ in the presence of NO.     

Exchange reactions of distibines

Distibines of the type R₂SbSbR′₂ with R = CH₃, R′ = C₂H₅ (1), R = CH₃, R′= n-C₃H₇ (2), R = CH₃, R′= C₆H₅ (3), R = C₂H₅, R′= C₆H₅ (4), R = n-C₃H₇, R′ = C₆H₅ (5), and R = CH₃, R′ = 2,4,6-(CH₃)₂C₆H₂ (6) are formed in equilibria by exchange reactions of the respective distibines of the type R₄Sb₂ and R′₄Sb₂.     

Synthesis and properties of alkyldicyclopentadienyl-vanadium(III) compounds

The compounds Cp₂VR (R = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂C(CH₃)₃ or CH₂Si(CH₃)₃) have been prepared from Cp₂ VCl and RMgX in n-pentane. The air-sensitive compounds are stable at room temperature, but decompose between 65 and 138°C. The thermal stability decreases in the order R = CH₃ CH₂Si(CH₃)₃ > C₂H₅ > CH₂C(CH₃)₃ > n-C₅H₁₁ > n-C₄H₉ > n-C₃H₇. Compounds with R = i-C₃H₇ or t-C₄H₉ could not be obtained.     

Theoretical Study on the Kinetics for the Reactions of Heptyl Radicals with Methanol

Ab initio study of the reactions of n-heptyl radicals(1-C₇H₁₅, 2-C₇H₁₅, 3-C₇H₁₅, and 4-C₇H₁₅) with methanol was conducted over the temperature range of 300-1500 K. Transition states for the reaction channels producing C₇H₁₅OH, CH₃, C₇H₁₅OCH₃, H, C₇H₁₆, CH₂OH and CH₃O were identified and the geometries of all stationary points were calculated at BB1K/MG3S level of theory. The potential barrier heights of the corresponding transition states were predicted by the CBS-QB3//BB1K and G4//BB1K methods, indicating that the eight H-abstraction channels are more kinetically favorable than the channels where OH transfers from CH₃OH to C₇H₁₅ and where the C₇H₁₅OCH₃+H products are given. The rate constants of H-abstraction channels were calculated with TST and TST/Eck. Both the forward and reverse rate constants have positive temperature dependence and the tunneling effect is only important at the temperature lower than 700 K. For the reactions of H-atom abstraction from methyl in CH₃OH by n-heptyl, a reverse and the corresponding forward rate constant are roughly equal. For the reactions of H-atom abstraction from OH in CH₃OH by n-heptyl, a reverse rate constant is larger by several orders of magnitude than the corresponding forward one.     

Gold(I) complexes with thiolate and triphenylphosphine ligands

The reaction of [AuCl(PPh₃)] with Pb(SR)₂(R = C₂H₅, C₆H₅, CH₂C₆H₅, C₆F₅, C₆H₂Me₃-2,4,6, Prⁱ and Bu^t) provides a clean method to obtain complexes of the type [Au(SR)(PPh₃)] in good yields. The new compounds have been characterized by IR, ¹H, ³¹P, ¹⁹F and ³¹C NMR. A study by FAB mass spectrometry indicates that an ion-molecule aggregation process takes place.     

Syntheses of heterocyclic compounds—I Cyclization of N-substituted O-nitroanilines

Internal cyclization of a nitrogroup was carried out by heating the N-substituted o-nitroanilines (I; R=C₆H₁₁---, C₆H₅.CH₂, C₆H₅.CH₂.CH₂---, X=NH) in the presence of ferrous oxalate¹ (Waterman and Vivian's method) as a potential route to partly hydrogenated nitrogen heterocycles. A mechanism for this type of ring-closure is proposed.