I2‐catalyzed reactions of schiff base and alkyl aldehyde towards benzo[f]quinoline derivatives

A mild, efficient, and general method for the synthesis of benzo[f]quinoline derivatives via a molecular iodine‐catalyzed reaction of Schiff base with alkyl aldehydes has been described. The structure of 3o was confirmed by X‐ray diffraction study.     

Characterization of CoMCM-41 mesoporous molecular sieves obtained by the microwave irradiation method

CoMCM-41 mesoporous molecular sieves with different amounts of cobalt were synthesized via the microwave irradiation method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), temperature programmed reduction (TPR), transmission electron microscopy (TEM) and N₂ adsorption-desorption technique, and thermal and hydrothermal stabilities of synthesized CoMCM-41 samples were also investigated. Results show that these synthesized materials have typical mesoporous structure of MCM-41. Also, specific surface area and pore volume of synthesized CoMCM-41 decrease with increasing amount of cobalt added, and mesoporous ordering also decreases. When the molar ratio of SiO₂:CoO in the starting material is 1.0:0.05, mesoporous ordering of synthesized CoMCM-41 is the best among the four doping contents. On the other hand, results of thermal and hydrothermal tests show that CoMCM-41 after calcination at 750 °C for 3 h or hydrothermal treatment at 100 °C for 5 days still retains mesostructure. However, mesoporous framework is entirely damaged after calcination at 850 °C for 3 h.     

利用空间位阻和氢溢流协同作用促进5-羟甲基糠醛选择性加氢制备5-甲基糠醛

Selective hydrogenation is a vital class of reaction. Various unsaturated functional groups in organic compounds, such as aromatic rings, alkynyl (C≡C), carbonyl (C＝O), nitro (-NO₂), and alkenyl (C＝C) groups, are typical targets in selective hydrogenation. Therefore, selectivity is a key indicator of the efficiency of a designed hydrogenation reaction. 5-(Hydroxymethyl)furfural (HMF) is an important platform compound in the context of biomass conversion, and recently, the hydrogenation of HMF to produce fuels and other valuable chemicals has received significant attention. Controlling the selectivity of HMF hydrogenation is paramount because of the different reducible functional groups (C＝O, C-OH, and C＝C) in HMF. Moreover, the exploration of new routes for hydrogenating HMF to valuable chemicals is becoming attractive. 5-Methylfurfural (MF) is also an important organic compound; thus, the selective hydrogenation of HMF to MF is an essential synthetic route. However, this reaction has challenging thermodynamic and kinetic aspects, making it difficult to realize. Herein, we propose a strategy to design a highly efficient catalytic system for selective hydrogenation by exploiting the synergy between steric hindrance and hydrogen spillover. The design and preparation of the Pt@PVP/Nb₂O₅ catalyst (PVP = polyvinyl pyrrolidone; Nb₂O₅ = niobium(V) oxide) were also conducted. Surprisingly, HMF could be converted to MF with 92% selectivity at 100% HMF conversion. The reaction pathway was revealed through the combination of control experiments and density functional theory calculations. Although PVP blocked HMF from accessing the surface of Pt, hydrogen (H₂) could be activated on the surface of Pt due to its small molecular size, and the activated H₂ could migrate to the surface of Nb₂O₅ through a phenomenon called H₂ spillover. The Lewis acidic surface of Nb₂O₅ could not adsorb the C＝O group but could adsorb and activate the C-OH group of HMF; therefore, when HMF was adsorbed on Nb₂O₅, the C-OH groups were hydrogenated by the spilled over H₂ to form MF. The high selectivity of this reaction was realized because of the unique combination of steric effects, hydrogen spillover, and tuning of the electronic states of the Pt and Nb₂O₅ surfaces. This new route for producing MF has great potential for practical application owing to its discovered advantages. We believe that this novel strategy can be used to design catalysts for other selective hydrogenation reactions. Furthermore, this study demonstrates a significant breakthrough in selective hydrogenation, which will be of interest to researchers working on the utilization of biomass, organic synthesis, catalysis, and other related fields.      

Molecular Nickel Thiolate Complexes for Electrochemical Reduction of CO2 to C1–3 Hydrocarbons

We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes ( 1 – 5 ) in reducing CO₂ to C_1–3 hydrocarbons on carbon paper in pH-neutral aqueous solutions. Ni(mpo)₂ ( 3 , mpo=2-mercaptopyridyl-N-oxide), Ni(pyS)₃⁻ ( 4 , pyS=2-mercaptopyridine), and Ni(mp)₂⁻ ( 5 , mp=2-mercaptophenolate) were found to generate C₃ products from CO₂ for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C₁, C₂, C₃ hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FE_C1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO₂ reduction.     

Enhanced Four-Electron Oxygen Reduction Selectivity of Clamp-Shaped Cobalt(II) Porphyrin(2.1.2.1) Complexes

The molecular structure, electrochemistry, spectroelectrochemistry and electrocatalytic oxygen reduction reaction (ORR) features of two Co^II porphyrin(2.1.2.1) complexes bearing Ph or F₅Ph groups at the two meso-positions of the macrocycle are examined. Single crystal X-ray analysis reveal a highly bent, nonplanar macrocyclic conformation of the complex resulting in clamp-shaped molecular structures. Cyclic voltammetry paired with UV/Vis spectroelectrochemistry in PhCN/0.1 M TBAP suggest that the first electron addition corresponds to a macrocyclic-centered reduction while spectral changes observed during the first oxidation are consistent with a metal-centered Co^II/Co^III process. The activity of the clamp-shaped complexes towards heterogeneous ORR in 0.1 M KOH show selectivity towards the 4e⁻ ORR pathway giving H₂O. DFT first-principle calculations on the porphyrin catalyst indicates a lower overpotential for 4e⁻ ORR as compared to the 2e⁻ pathway, consistent with experimental data.     

邻-(N-芳酰基-N-甲氨基苯)-二硫化合物的合成：通过N-甲基-2-单芳基苯并噻唑啉在溶剂中的自发偶联反应和它们的血管内皮生长因子抑制活性

N-甲基-2-单芳基苯并噻唑啉 (1) 在固体状态时可以稳定地储藏在空气中。但是,它们在不同溶剂中却表现出了不同的行为。在醇溶液或二甲亚砜-水的体系中,1相对稳定;而在其它有机溶剂如：丙酮,氯仿,二氯甲烷和乙酸乙酯等溶剂中,会发生自发偶联反应生成相应的邻-(N-芳酰基-N-甲氨基苯)-二硫化合物 (2)。对这些新的化合物 (1) 和 (2) 进行了体外人乳腺癌细胞 (MDA-MB-231) 血管内皮生长因子靶点筛选,大部分化合物都表现出了抑制活性。实验结果表明这两类化合物 (1) 和 (2) 作为血管内皮生长因子抑制剂值得进行深入研究。     

二元无机物标准熵 So298的拓扑研究

为了预测二元无机物的标准熵,基于分子图的连接矩阵和离子参数gi、qi,提出了一种新的连接性指数mQ, mG及其逆指数mQ’, mG’。 qi、gi定义为：qi=(1.1+Zi1.1) /(1.7+ni), gi=(1.4+Zi) /(0.9+ri+ri-1),其中Zi 、ni和 ri分别代表离子i的电荷数、最外层主量子数和半径。从0Q, 0Q’, 1G,和1G’,利用多元线性回归分析方法和人工神经网络方法,可以构建优良的QSPR模型。对371个二元无机物,其多元线性模型及神经网络模型的相关系数、标准偏差和平均绝对偏差分别是：0.9905, 8.29 J.K-1.mol-1, 6.48 J. K-1.mol-1, 0.9960, 5.37 J.K-1.mol-1 和 3.90 J.K-1.mol-1。留一法交叉验证表明,其多元线性模型具有良好的稳定性。两个模型对187个未进入模型的二元无机物的标准熵的预测值和实验值之间的相关系数、标准偏差和平均绝对偏差分别是：0.9897, 8.64 J. K-1.mol-1, 6.84 J. K-1.mol-1, 0.9957, 5.63 J.K-1.mol-1, 和 4.18 J.K-1.mol-1。研究表明,本文方法在预测二元无机物标准熵时比文献方法更有效,两种模型均能较精确的预测二元无机物的标准熵,且神经网络模型的预测结果更精确。     

Preparation of a Novel COOH Ion Implantation Sensor and Its Application

A novel ion implantation sensor (DNA/COOH/ITO) based on DNA immobilization in COOH/ITO probe was manufactured for the first time. The surface morphologies of the electrodes were characterized by X‐ray photoelectron spectroscopy (XPS), field‐emission‐scanning electron microscopy (FSEM) and electrochemical methods. In a 0.5 mol/L PBS solution, a sensitive oxidation peak of DNA on the COOH/ITO electrode was obtained by voltammetry. The electrochemical behavior of DNA was studied. And the oxidative peak potential of DNA was +0.400 V (vs. Ag/AgCl). Its peak current was proportional to the concentration of DNA over the range of 1.0×10^?8?1.0×10^?6 mol/L with a detection limit of 5.0×10^?9 mol/L (about 0.5 ng/mL). This sensor was applied to the direct detection of DNA samples.     

Determination and dynamics of difenoconazole residues in Chinese cabbage and soil

An analytical method was developed using a solid phase extraction （SPE） cleanup and gas chromatography for detecting the residues of difenoconazole in Chinese cabbage and soil. The recovery and the relative standard deviation of this method in Chinese cabbage was 87.6-99.0%, 1.71-10.50%, respectively; in soil was 92.4-95.5%, 4.93-10.70%, respectively. Further degradation of difenoconazole residue in Chinese cabbage and soil was studied to evaluate residue behavior and environmental safety of difenoconazole. Degradation rate of difenoconazole in both Chinese cabbage and soil followed the first order kinetics with the half-lives of 6.6-7.8 and 54.2-55.0 days, respectively.     

Novel Zn（Ⅱ） ladder-like coordination polymer constructed from designed ferrocenyl ligand

Reaction of Zn（NO3）2·6H2O with 3-（4-carboxylphenylamino）-l-ferrocenyl-2-butylen-l-one （HL） and 4,4′-bipyfidine （4,4′- bipy） in methanol solution resulted in a novel ladder-like coordination polymer {[Zn2L2（μ2-L）2（4,4′-bipy）2]·MeOH}n （1）. Its crystal structure, thermal and electrochemical properties are presented.