固体酸催化酯化的研究─—对苯二甲酸辛酯的合成

用半经验方法ＣＮＤＯ／２计算了对苯二甲酸等羧酸分子的结构，讨论了对苯二甲酸分子的结构特点，探讨了以Ｎａ＿２ＳＯ＿４－Ａｌ＿２Ｏ＿３体系催化对苯二甲酸辛酯的合成。     

Designable assembly of atomically precise Al4O4 cubane supported mesoporous heterometallic architectures

Heterometallic cluster-based framework materials are of interest in terms of both their porous structures and multi-metallic reactivity. However, such materials have not yet been extensively investigated because of difficulties in their synthesis and structural characterization. Herein, we reported the designable synthesis of atomically precise heterometallic cluster-based framework compounds and their application as catalysts in aldol reactions. By using the synergistic coordination protocol, we successfully isolated a broad range of compounds with the general formula, [Al₄M₄O₄(L)₁₂(DABCO)₂] (L = carboxylates; DABCO = 1,4-diazabicyclo[2.2.2]-octane; M²⁺ = Co²⁺, Mn²⁺, Zn²⁺, Fe²⁺, Cd²⁺). The basic heterometallic building blocks contain unprecedented main-group γ-alumina moieties and surrounding unsaturated transition metal centers. Interestingly, the porosity and interpenetration of these frameworks can be rationally regulated through the unprecedented strategy of increment of the metal radius in addition to general introduction of sterically bulky groups on the ligand. Furthermore, these porous materials are effective catalysts for aldol reactions. This work provides a catalytic molecular model platform with accurate molecular bonding between the supporters and catalytically active metal ions.

Mesoporous heterometallic architectures are designed by the incorporation of the Al₄O₄ cubane and interpenetration regulation.     

Ion-Functionalized Silver(I) Carboxylates: Synthesis and Application in Ru-Catalyzed Olefin Metathesis Reaction

Russian Journal of General Chemistry - The Grubbs–Hoveyda catalysts have a wide range of applications in catalyzed formation of the carbon-carbon double bonds. In this study, several...     

Au@ZIF-8核壳结构中金纳米粒子分布的调控及其在荧光分子光致发光传感中的应用

控制金属@MOF核壳纳米结构中金属纳米粒子的分布不容易实现。我们应用了合成MOF胶体粒子所用到的配位调制方法来合成Au@ZIF-8核壳纳米结构。通过使用过量的2-甲基咪唑和不同用量的1-甲基咪唑可获得不同的Au@ZIF-8。该合成方法可在ZIF-8纳米晶体中灵活调整Au纳米粒子（Au NPs）的分布。此外,我们分别研究了2种不同尺寸的荧光分子与Au@ZIF-8结合后的光致发光光谱和寿命。ZIF-8的孔径可以决定这2种分子是否可通过多孔壳结构接近Au NPs。分子光学特性对Au NPs近场的发光增强和荧光猝灭的竞争非常敏感。     

黄酮类化合物的高效毛细管电泳分析

综述了近10年来高效毛细管电泳在黄酮类分析中的应用．着重介绍了黄酮类化合物毛细管电泳的CZE与MEKC两种模式的分离情况,同时简要介绍了黄酮类的结构与其电泳迁移行为的关系．     

Fast determination of trace dimethyl fumarate in milk with near infrared spectroscopy following fluidized bed enrichment

Near infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool in different fields. However, because of the low sensitivity in near infrared region, it is a significant challenge to detect trace analytes with normal NIRS technique. A novel enrichment technique called fluidized bed enrichment has been developed recently to improve sensitivity of NIRS which allows a large volume solution to pass through within a short time. In this paper, fluidized bed enrichment method was applied in the determination of trace dimethyl fumarate in milk. Macroporous styrene resin HZ-816 was used as adsorbent material, and 1?L solution of dimethyl fumarate was run to pass through the material for concentration. The milk sample was pretreated to remove interference matters such as protein, fat, and then passed through the material for enrichment; after that, diffuse reflection NIR spectra were measured for the analyte concentrated on the material directly without any elution process. The enrichment and spectral measurement procedures were easy to operate. NIR spectra in 900–1,700?nm were collected for dimethyl fumarate solutions in the concentration range of 0.506–5.060?μg/mL and then used for multivariate calibration with partial least squares (PLS) regression. Spectral pretreatment methods such as multiplicative scatter correction, first derivative, second derivative, and their combinations were carried out to select the optimal PLS model. Root mean square error of cross-validation calculated by leave-one-out cross-validation is 0.430?μg/mL with ten PLS factors. Ten samples in an independent test set were predicted by the model with the mean relative error of 5.33?%. From the results shown in this work, it can be concluded that the NIR technique coupled with on-line enrichment method can be expanded for the determination of trace analytes, and its applications in real liquid samples like milk and juice may also be feasible.     

QM/MM Study on Enzymatic Mechanism in Sinigrin Biosynthesis

As the major and abundant type of glucosinolates (GL) in plants, sinigrin has potential functions in promoting health and insect defense. The final step in the biosynthesis of sinigrin core structure is highly representative in GL compounds, which corresponds to the process from 3-methylthiopropyl ds-GL to 3-methylthiopropyl GL catalyzed by sulfotransferase (SOT). However, due to the lack of the crystallographic structure of SOT complexed with the 3-methylthiopropyl GL, little is known about this sulfonation process. Fortunately, the crystal structure of SOT 18 from Arabidopsis thaliana (AtSOT18) containing the substance (sinigrin) similar to 3-methylthiopropyl GL has been determined. To understand the enzymatic mechanism, we employed molecular dynamics (MD) simulation and quantum mechanics combined with molecular mechanics (QM/MM) methods to study the conversion from ds-sinigrin to sinigrin catalyzed by AtSOT18. The calculated results demonstrate that the reaction occurs through a concerted dissociative mechanism. Moreover, Lys93, Thr96, Thr97, Tyr130, His155, and two enzyme peptide chains (Pro92-Lys93 and Gln95-Thr96-Thr97) play a role in positioning the substrates and promoting the catalytic reaction by stabilizing the transition state geometry. Particularly, His155 acts as a catalytic base while Lys93 acts as a catalytic acid in the reaction process. The presently proposed concerted dissociative mechanism explains the role of AtSOT18 in sinigrin biosynthesis, and could be instructive for the study of GL biosynthesis catalyzed by other SOTs.     

采用铁基催化剂在V型热解火焰中合成碳纳米管的实验研究

催化剂的选取对于V型热解火焰合成碳纳米管具有重要的影响.实验中分别采用五羰基铁、二茂铁、纳米铁粉等作为催化剂,取样时间为10 min,温度约为1150 K,催化剂的引入方式为喷雾热解方法,利用扫描电镜和透射电镜对合成的碳纳米管进行形态和结构表征分析.实验结果表明:利用V型热解火焰合成碳纳米管时的关键物质是纳米氧化铁颗粒...     

具有高稳定性以及光催化产氢活性的奇数环状异金属钛氧纳米团簇

利用太阳能是解决当前能源危机和环境问题的有效途径.二氧化钛是一种稳定性高、环境友好的新型光催化剂.近年来,具有精确结构信息的晶态钛氧团簇(PTCs)作为TiO2的分子结构模型受到广泛关注.目前大多数PTCs含有烷氧基,在空气中易发生水解.这在很大程度上限制了对其光催化性能的研究.在无机钛氧簇的外围修饰大量的共轭有机配体...