氩离子激光固化环氧树脂制作三维微结构

利用激光束进行三维成像是通过逐层光引发聚合形成宏观尺度的三维实体 .最近出现的激光全息光刻技术是利用激光束的干涉产生三维全息图案 ,让感光树脂在全息图案中曝光 ,从而一次形成三维周期有序微结构 .通过调节激光干涉及波长可控制三维结构的形状及尺寸 .利用该技术获得亚微米尺度上周期性重复的三维微结构 ,可用于制作三维光子晶体 [1,2 ]等具有独特性能的聚合物材料 .本文用铁芳烃化合物与特种环氧树脂配制成阳离子型可见光固化树脂 ,在氩离子激光器产生的多束可见连续激光相干形成的空间干涉光场中曝光 ,成功地制备出亚微米量级的三…     

奎宁修饰的纳米铑簇合物催化丙酮酸乙酯对映选择性加氢反应研究

研究了奎宁作手性修饰剂修饰的负载型纳米铑簇合物催化剂 (Rh/ PVP-γ-Al2 O3)催化丙酮酸乙酯不对称氢化反应 ,在该反应中手性修饰剂奎宁不仅具有手性诱导作用 ,而且还有明显加速反应的作用 ;载体γ-Al2 O3在促进提高催化剂活性和对映选择性方面也有很重要的影响 .在优化的反应条件 [2 0℃ ,7.0 MPaH2 ,c(奎宁 ) =3 .86× 1 0 - 3mol/ L,四氢呋喃作溶剂 ]下 ,丙酮酸乙酯不对称加氢的转化频率 (TOF)为871 h- 1 ,对映选择性达到了 5 4.7% ;反应温度降低到 3℃时 ,对映选择性达到 5 9.2 % .     

Mn(Ⅱ)/Mn(Ⅲ)电对在硫酸溶液中氧化还原行为

采用循环伏安法对Mn(Ⅱ)/Mn(Ⅲ)电对在硫酸溶液中铂电极上的氧化还原与Mn(Ⅱ)浓度、酸浓度、扫描速率、温度以及对流因素的函数关系进行了研究.结果发现,Mn(Ⅱ)在铂电极上Mn(Ⅱ)的氧化及Mn(Ⅲ)的还原均受扩散控制；升高温度和磁搅拌均能增加Mn(Ⅱ)氧化为Mn(Ⅲ)的速率；增加酸浓度和Mn(Ⅱ)浓度有利于增加Mn(Ⅲ)的稳定性,减少Mn(Ⅲ)的歧化和水解.     

发用防晒剂DDABDT的反相高效液相色谱法测定

建立了反相高效液相色谱法测定发用防晒剂二甲基对胺基苯甲酰胺丙基十二烷基二甲胺甲苯磺酸盐(简称DDABDT)的方法.采用的色谱条件为色谱柱Symmetry C8柱,流动相为V(乙腈):V(10 mmol/L NaAc)=65:35溶液(含体积分数0.02%三氟乙酸,pH5.04),流速1.0 mL/min;检测波长305 nm;进样量20μL.DDABDT质量浓度为0.05～1000 mg/L时,其浓度与峰面积呈良好的线性关系(R2＞0.999),检出限为0.02 mg/L(S/N=3).洗发水A中DDABDT的回收率在98.0%～102%之间,发样提取液中DDABDT的平均回收率在85%～108%之间.洗发水中DDABDT浓度测定日内和日间相对标准分别为1.2%,3.4%.头发吸附DDABDT含量测定日内和日间相对标准偏差(RSD)分别为9.1%,9.8%.同时以高效液相色谱-电喷雾离子化质谱对色谱法测定样品的DDABDT峰进行了验证.该方法已用于洗发水及头发吸附DDABDT的分析.     

温度控制的原位脱羧3-氟邻苯二甲酸与铅(Ⅱ)配位聚合物的合成、晶体结构及荧光性质

Pb(NO₃)₂与3-氟邻苯二甲酸(H₂Fpht)和2,2'-联吡啶(bpy)在不同水热反应温度下获得了2个新的配位聚合物:[Pb(Fba)(bpy)(NO₃)] _n (1)和[Pb₄O₂(Fba)₄] _n (2)。3-氟邻苯二甲酸配体经由原位脱羧生成了3-氟苯甲酸根(Fba)。配合物1具有Pb-NO₃-Pb双螺旋链结构,是由硝酸根桥联四方反棱柱[PbO₆N₂] 结构单元而形成,而Fba与bpy配体螯合配位于中心铅离子。配合物2为Pb-OH-Pb链状结构,包含四面体结构单元[Pb₄( μ₄-OH)₄] ⁴⁺,且具有4个晶体学独立的铅离子中心:Pb(1)O₆、Pb(2)O₆、Pb(3)O₅和Pb(4)O₅。这两个配合物链分别经氢键作用力自组装为三维超分子网络结构。室温下,测定了配合物的固体荧光光谱,均显示为基于配体的荧光发射。有意思的是,通过荧光淬灭机理配合物2可以选择性地检测硝基苯。     

Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper‐Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate

In this work, we have successfully synthesized a new family of chiral Schiff base–phosphine ligands derived from chiral binaphthol (BINOL) and chiral primary amine. The controllable synthesis of a novel hexadentate and tetradentate N,O,P ligand that contains both axial and sp³‐central chirality from axial BINOL and sp³‐central primary amine led to the establishment of an efficient multifunctional N,O,P ligand for copper‐catalyzed conjugate addition of an organozinc reagent. In the asymmetric conjugate reaction of organozinc reagents to enones, the polymer‐like bimetallic multinuclear Cu? Zn complex constructed in situ was found to be substrate‐selective and a highly excellent catalyst for diethylzinc reagents in terms of enantioselectivity (up to >99 % ee). More importantly, the chirality matching between different chiral sources, C₂‐axial binaphthol and sp³‐central chiral phosphine, was crucial to the enantioselective induction in this reaction. The experimental results indicated that our chiral ligand (R,S,S)‐ L1 ‐ and (R,S)‐ L4 ‐based bimetallic complex catalyst system exhibited the highest catalytic performance to date in terms of enantioselectivity and conversion even in the presence of 0.005 mol % of catalyst (S/C=20 000, turnover number (TON)=17 600). We also studied the tandem silylation or acylation of enantiomerically enriched zinc enolates that formed in situ from copper‐ L4 ‐complex‐catalyzed conjugate addition, which resulted in the high‐yield synthesis of chiral silyl enol ethers and enoacetates, respectively. Furthermore, the specialized structure of the present multifunctional N,O,P ligand L1 or L4 , and the corresponding mechanistic study of the copper catalyst system were investigated by ³¹P NMR spectroscopy, circular dichroism (CD), and UV/Vis absorption.     

Theoretical computation of low‐lying electronic states of HCNS: A CASPT2 study

Complete active space self‐consistent field (CASSCF) and complete active space second‐order perturbation theory (CASPT2) calculations in conjunction with the aug‐cc‐pVTZ basis set have been used to investigate the low‐lying electronic states of thiofulminic acid (HCNS), HCNS⁺, and HCNS^?. The result of geometry optimization using CASPT2/aug‐cc‐pVTZ shows that theoretically determined geometric parameters and harmonic vibrational frequencies for the HCNS ground state X¹Σ⁺(X¹A′) are in agreement with previous studies. The ionization energies, the electron affinity energies, the adiabatic excitation energies, and vertical excitation energies have been calculated and the corresponding cation and anion states are identified. By calculating adiabatic electron affinity, the states of HCNS^? have been identified to contain both π orbital states (X²A′ and 1²A″) and dipole‐bond states (1⁴A′ and 1⁴A″). © 2012 Wiley Periodicals, Inc.     

阿奇霉素在多壁碳纳米管修饰电极上的电化学行为及其测定

运用循环伏安法与线性扫描伏安法研究了阿奇霉素在多壁碳纳米管修饰玻碳电极上的电化学行为,建立了一种直接测定阿奇霉素的电化学分析方法。结果表明,与裸玻碳电极相比,多壁碳纳米管修饰电极能显著提高阿奇霉素的氧化峰电流,阿奇霉素的电极过程完全不可逆,存在典型的吸附特性。在优化的实验条件下,氧化峰电流与阿奇霉素浓度在3.0×10-7～2.5×10-5 mol/L和2.5×10-5～5.0×10-4 mol/L范围内呈现良好的线性关系,检出限为1.0×10-7 mol/L。     

Ge@C82结构及性质的理论研究

采用密度泛函理论方法,对Ge@C82的结构及性质进行计算研究.结果表明,由于包合Ge,C82碳笼平均键长增长,碳笼增大,而且Ge原子略微偏离碳笼中心.三重态的C2Ge@C82为能量最低结构.自然布居分析表明,C2C82与Ge之间未发生电子转移,可以用C2Ge@C82来表示它的结构.C2C82和C2Ge@C82的红外光谱计算结果显示,二者的主要区别为C2Ge@C82在1100～1200 cm-1区间的吸收峰变得更尖锐.     

一种腙水解合成醛(酮)的绿色化学方法

腙与二水合氯化铜在80%乙腈溶液中回流反应1 h～3 h,高收率地制得相应的醛(酮)。实现了铜盐的循环使用,符合绿色化学理念。