关于气相渗透法仪器常数问题——一个新模式

气相渗透法广泛用于测定齐聚物和低分子量聚合物的数均分子量(M_n)。分析文献数据和本文的实验证明,仪器常数K值随溶质的分子量而变化。本文提出了一种新的说明 VPO法 K值依赖于溶质分子量的模式,根据此模式,可清楚地说明这种依赖关系。     

Visible-light-initiated malic acid-promoted cascade coupling/cyclization of aromatic amines and KSCN to 2-aminobenzothiazoles without photocatalyst

By using ambient air as the oxidant and malic acid as the promoter, a practical method for the preparation of 2-aminobenzothiazoles through visible-light-initiated cascade reaction of aromatic amines and KSCN in eco-friendly bis(methoxypropy)ether under metal-, hazardous additive-, photocatalyst-free conditions was established.     

溶剂热法制备Ag/TiO2纳米材料及其光催化性能

以乙醇为溶剂, 钛酸四丁酯为前驱体, 用溶剂热法制备了Ag表面修饰的负载型纳米二氧化钛光催化剂. 利用X射线衍射(XRD)、N₂吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱等技术对其进行了系统的表征, 以亚甲基蓝(MB)溶液的脱色降解为模型反应, 考察了不同Ag含量样品的光催化性能. 结果表明: 用溶剂热法制备的样品中TiO₂皆为锐钛矿相, 金属Ag颗粒沉积在TiO₂表面, 粒径为2 nm左右, 比表面积较溶胶凝胶法制备的样品大大增加, 最高可达151.44 m²·g^-1; UV-Vis光谱和光催化实验表明: Ag修饰使TiO₂对光的吸收能力大大增强, 吸收带边红移至可见光区, 亚甲基蓝在该复合材料上的光催化降解反应遵循一级反应动力学模型; 溶剂热法制备样品的光催化性能明显好于溶胶凝胶法制备的样品, 在紫外光和可见光下, Ag摩尔分数为5%的样品表现出最佳的光催化活性.     

嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法分析痕量铬的形态

研究了嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法对尿中痕量铬的形态分析方法,探讨了嵌段分子筛聚合材料P123-SH吸附铬的原理和最佳条件。在pH 7.0、常温下,Cr3+和Cr(Ⅵ)被很好的分离,且Cr3+可被该材料定量吸附,其吸附容量为6.15 mg/g。吸附的Cr3+可用2 mol/L的HCl洗脱,用石墨炉原子吸收法测定洗脱下来的Cr3+,往溶液中加入0.1%抗坏血酸将Cr(Ⅵ)还原为Cr3+测总铬,Cr(Ⅵ)含量为总铬减去Cr3+,方法测定Cr3+的检出限为0.011μg/L(3σ,n=11),线性范围为0.1～10μg/L,加标回收率在94%～106%之间,对0.50μg/L的Cr3+溶液平行测定7次,RSD为3.6%。方法可应用于生物样品和环境样品中痕量铬的形态分析。     

Synthesis,characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(BPIP)] and [Ru(phen)2(BPIP)] (BPIP = 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline)

New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)₂(BPIP)]²⁺ (1) (bpy = 2,2′-bipyridine) and [Ru(phen)₂(BPIP)]²⁺ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, ¹H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365 nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA.     

碰撞能量对反应Sr＋HF转动取向的影响

在推广LEPS势能面上,用经典轨线方法,研究了反应碰撞能量对反应Sr＋HF的转动取向的影响.计算结果与产物轨道角动量模型进行比较.计算结果表明,随着碰撞能量的增加,产物转动取向越强烈.     

Interlocked catenane-like structure predicted in Au24(SR)20: implication to structural evolution of thiolated gold clusters from homoleptic gold(I) thiolates to core-stacked nanoparticles

Atomic structure of a recently synthesized ligand-covered cluster Au(24)(SR)(20) [J. Phys. Chem. Lett., 2010, 1, 1003] is resolved based on the developed classical force-field based divide-and-protect approach. The computed UV-vis absorption spectrum and powder X-ray diffraction (XRD) curve for the lowest-energy isomer are in good agreement with experimental measurements. Unique catenane-like staple motifs are predicted for the first time in core-stacked thiolate-group (RS-) covered gold nanoparticles (RS-AuNPs), suggesting the onset of structural transformation in RS-AuNPs at relatively low Au/SR ratio. Since the lowest-energy structure of Au(24)(SR)(20) entails interlocked Au(5)(SR)(4) and Au(7)(SR)(6) oligomers, it supports a recently proposed growth model of RS-AuNPs [J. Phys. Chem. Lett., 2011, 2, 990], that is, Au(n)(SR)(n-1) oligomers are formed during the initial growth of RS-AuNPs. By comparing the Au-core structure of Au(24)(SR)(20) with other structurally resolved RS-AuNPs, we conclude that the tetrahedral Au(4) motif is a prevalent structural unit for small-sized RS-AuNPs with relatively low Au/SR ratio. The structural prediction of Au(24)(SR)(20) offers additional insights into the structural evolution of thiolated gold clusters from homoleptic gold(I) thiolate to core-stacked RS-AuNPs. Specifically, with the increase of interfacial bond length of Au(core)-S in RS-AuNPs, increasingly larger "metallic" Au-core is formed, which results in smaller HOMO-LUMO (or optical) gap. Calculations of electronic structures and UV-vis absorption spectra of Au(24)(SR)(20) and larger RS-AuNPs (up to ~2 nm in size) show that the ligand layer can strongly affect optical absorption behavior of RS-AuNPs.     

Helical Poly(α,β‐unsaturated ketone) with Bulky Pendant of Binaphthyl from Anionic Polymerization of ((−)‐Menthyl (S)‐6′‐Acrylyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate

((?)‐Menthyl (S)‐6′‐acrylyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate ( 3 ) was synthesized and anionically polymerized using n‐BuLi as an initiator in toluene. The monomer 3 was levorotatory and had an [α]_D²⁵ value of ?72.4, but its corresponding polymer poly‐ 3 was dextrorotatory and showed an [α]_D²⁵ value of +162.0. Poly‐ 3 was confirmed to exist in the form of one‐handed helical structure in solution by means of comparing the specific optical rotation and the CD spectra with that of 3 and the model compounds such as (?)‐menthyl (S)‐6′‐propionyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2b and (?)‐menthyl (S)‐6′‐heptanoyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2c . This conclusion was also confirmed by the fact that the g‐value of poly‐ 3 is about 11 times of that of monomer 3 .     

Naryl-substituted anthranilamides with intramolecular hydrogen bonds

Hydrogen bonding interaction as one type of non-covalent force has proven itself to be highly efficient for constructing structurally unique artificial secondary structures. Here, the structure of N_aryl-substituted anthranilamide in solution is demonstrated by various NMR technique, the intramolecular hydrogen bonds between amide attached to arylamine of the same ring is proposed, which is supported by its crystal structure in the solid phase. The substituent on the nitrogen atom of arylamine plays an important role in forming the presence of intramolecular hydrogen bonds. The chemical shift of the N_aryl-H downfield changes obviously, due to the formation of intramolecular hydrogen bonds and the deshielding effect of oxygen, and the neighboring C–H is activated and shows downfield protonic signal too. The presence of intramolecular hydrogen bonds probably provides the explanation for the transformation from N_aryl-substituted anthranilamide to imine, which could be converted into 2-aryl quinazolinone finally.