Facile synthesis of ZnO nanoparticles for the photocatalytic degradation of methylene blue

Journal of Sol-Gel Science and Technology - ZnO nanoparticle photocatalysts with a grain size range of 20–100?nm were prepared via a simple sol–gel method and characterized by...     

4‐[2‐(4‐Methoxyphenyl)ethenyl]‐N‐methylpyridinium tetraphenylborate

In the cation of the title compound, C₁₅H₁₆NO⁺·C₂₄H₂₀B^?, the pyridyl ring makes a dihedral angle of 14.03° with the phenyl ring. The anion has a slightly distorted tetrahedral geometry and forms honeycomb‐like sheets which extend along the b axis, forming channels containing the cations. A comparison of packing energies reveals a difference between the title compound and a similar material which has non‐linear optical properties.     

相转移催化合成硫氰酸铵

以氨和二硫化碳为原料的传统合成硫氰酸铵 ( NH4 SCN)工艺分为加压法 [1,2 ]和常压法 [3,4 ] 2种 .常压法设备投资小 ,操作灵活 ,但常压因互不相溶的 CS2 、NH3两相反应体积小 ,速度慢 ,反应时间达 2 5 h以上 ,且 CS2 易挥发 ,使 NH4 SCN产率仅有 60 %左右 .表面活性剂作为相转移催化剂加快反应速度的应用已有报道 [5] .本文采用壬基酚四氧乙烯醚 ( OP- 4)和壬基酚二十一氧乙烯醚 ( OP- 2 1 )混合型催化剂用于 n( CS2 )∶ n( NH3) =1∶ 2 .5反应体系 ,在常温、常压及高速搅拌下 ,第 1步反应缩短为 4h,NH4 SCN产率提高到 70 %以…     

Determination of the residue of quizalofop-p-tefuryl in soybean by HPLC

A HPLC method was developed for the analysis of quizalofop-P-tefurylof in soybean. The samples were extracted with methanol-water (volume ratio), The extracts were cleaned up with a column of silica gel. The final residue was detected by HPLC, using a UV detector. The recoveries from the analytical method for soybean were 84.32%–89.25%. Variable coefficients were 0.49%∼1.51%. This method proved to be simple, reliable and accurate. __________ Translated from Chinese Journal of Chromatography, 2005, 23(2)(in Chinese)     

Theoretical exploration of the cooperative effect in NMF-NMF-amino acid residue hydrogen bonding system

This paper presents a theoretical study of the cooperative effect in sixteen linearly-arranged trimer systems consisting of N-methylformamide dimer and an extra amino acid residue. These trimer systems, NMF-NMF-AAR, in short, have been systematically investigated by full optimization at B3LYP/cc-pVTZ level and subsequent electronic energy calculations at PBE1PBE/cc-pVTZ, HF/cc-pVTZ and MP2/cc-pVTZ, respectively. Obvious spatial transformation due to energetic factors has been found in almost all the trimers. Systematic analysis in weak interaction energy components has shown that: (1) in these trimer systems, the bonding structure and the cooperative effect combine to determine the stability of both HB1 and HB2. For HB2, the structure of the constituent amino acid residue also plays a crucial role by interfering with the neighboring moieties; (2) the large contribution of the cooperative effect to the overall hydrogen bonding energy has claimed the importance of cooperativity in our systems; (3) the non-hydrogen bonding weak interaction components are found to be non-negligible in these trimer systems; (4) moreover, the cooperative effect between these non-hydrogen bonding components is always found to be positive. The good performances of PBE1PBE and PM6 have been established by comparisons between these methods.     

Photoinduced Oxidation Reaction of Benzotrifluoride with OH Radical by the Laser Flash Method

The optical transient and kinetics characterizations of the transients formed in the reaction of OH with benzotrifluoride (BTF) were performed by a laser flash photolysis technique. The results indicated that the formation of π‐type adduct of C₆H₅(OH)CF₃ was the major reaction channel, and the δ‐type adduct of C₆H₅CF₃OH formation was an additional minor process in the oxidation reaction of BTF attacked by OH radicals yielded from the photolysis of H₂O₂. Addition of OH to the CF₃ group led to the fluoride ion elimination to yield α,α‐difluorophenylcarbinol (C₆H₅CF₂OH). Trifluoromethylphenol (HOC₆H₄CF₃) of meta‐, para‐ and ortho‐substituted isomers resulted from the addition of OH to the BTF aromatic ring.     

High Sensitive Electrochemical Detection of Sequence‐Specific DNA Using Low Current Voltammetry

In this article, we report on efforts to construct a high sensitive electrochemical sensor with immobilized sandwich‐type DNA borne ferrocene (Fc) head for sequence‐specific DNA detection using ultramicroelectrode and low current voltammetry. Based on the difference in deformability between the bending rigid complementary DNA double helix and its anomalous flexile mismatches, the fully complementary target can be distinguished from mismatched targets including the single‐base mismatched target. Detection limit estimated as the amount of DNA is observed to be 100 fM via low current voltammetry. The method offers great promise of high sensitivity and selectivity simultaneously for effective gene identification.     

Green and high efficient synthesis of triaza‐benzo[b]fluoren‐6‐one derivatives in water under microwave irradiation

Triaza‐benzo[b]fluoren‐6‐one derivatives were synthesized via the three‐component reaction of aldehyde, cyclohexane‐1,3‐dione compound and 2‐aminobenzimidazole in water under microwave irradiation. The new protocol has the advantages of excellent yield, low cost, reduced environment impact, wide scope and convenient procedure.     

Recent advances in microfluidic fiber-spinning chemistry

Fiber-spinning chemistry (FSC) has emerged as a promising micro-reaction platform due to its high-specific surface area, efficient heat and mass transfer, and enhanced reaction rate. The FSC strategy employs spinning fibers as microreactors, lessening the emissions of volatile organic compounds (VOCs), and realizing the design of micro/nanoscale fibers and the synthesis of nanomaterials. In this review, we highlight the latest advancements in FSC in respect of preparation mechanisms and technical advantages. Various FSC strategies, including microfluidic spinning, electro-microfluidic spinning (EMS), and microfluidic blow spinning (MBS) are emphasized. In particular, the regulation of microfluidic chips in the FSC process is introduced. Additionally, the application of the FSC strategy is summarized in the synthesis of fluorescent nanomaterials, nonweaving for multidimensional fibers, and all-weather smart textiles. Finally, the advanced progress and future perspectives are discussed. Overall, this review will provide theoretical guidance for the design of well-defined micro/nanoscale fibers based on the FSC platforms.     

超大硅胺基氯锗宾的反应性与立方四锗卡宾的成键解析

超大硅胺基取代的低价锗化合物可以构建新颖的化学结构,提供有学术价值的新发现。二配位的超大硅胺基氯锗宾Ge(N(SiⁱPr₃)₂)Cl (1)具有空的4p轨道和孤电子对。针对这2个特点,研究了化合物1的热构型转换和菲醌氧化加成反应。1的温热分解生成了立方四锗卡宾 Ge₄(NSiⁱPr₃)₄ (2),与菲醌(L)定量氧化加成生成了胺基一氯菲二酚合锗(Ⅳ)：[Ge(N(SiⁱPr₃)₂)(L)Cl] (3)。表征了2个产物的单晶结构与组成。四锗卡宾2本质上是锗异腈的四聚体,分子呈现出畸变的立方体构型,4个Ge原子和4个N原子构成了中心立方体的 8个顶点。其中 Ge—N键长为 0.203 6(3) nm,N—Ge—N与 Ge—N—Ge的键角分别为 85.51(18)°和94.32(16)°,立方体的侧面接近平行四边形。理论计算首次揭示了四锗卡宾2的成键面貌。自然键轨道(NBO)给出Ge₄N₄骨架上的20个分子轨道。轨道定域化的计算结果完好地呈现出4对Ge孤对电子、12个Ge—N键和4个Si—N键的定域轨道,能量分别为-12.22、-15.12 和-20.12 eV。Ge 孤对电子主要保留了 4s 电子的特性,而 Ge—N 键主要由 N 的 2s 轨道(18.4%)和 2p 轨道(71.3%)、Ge的4s轨道(0.75%)和4p轨道(9.43%)综合贡献形成。在化合物3的分子中,Ge^Ⅳ采取sp³杂化,由于空间位阻与非对称配位,与另外4个配位原子形成非对称四面体构型。