硝酸体系中双功能离子液体萃取剂[A336][CA-12]/[A336][CA-100]萃取稀土的机理研究

研究了双功能离子液体萃取剂[A336][CA-12]/[A336][CA-100]在HNO3体系中对稀土的萃取性能.通过与有机羧酸类萃取剂CA- 12/CA- 100及中性有机膦(磷)类萃取剂TBP和P350的比较得知,在相同条件下,萃取能力按如下顺序降低:[A336] [CA- 12]/[A336] [CA- 100...     

全二维气相色谱/飞行时间质谱用于烟叶中酸性成分的分离与分析

建立了烟叶中酸性化合物(挥发性、 半挥发性羧酸类和酚类)组成研究的全二维气相色谱/飞行时间质谱(GC×GC-TOFMS)分析方法, 并用此方法对香料烟中的酸性化合物进行了表征. 用同时蒸馏萃取样品的前处理方法, 采用TOFMS谱图库检索结合全二维特有的包含结构信息的二维谱图, 通过族分离和结构谱图, 鉴定出了香料烟中143种挥发性及半挥发性酸性组分, 包括10种酸酐和呋喃二酮, 43种有机酸和90种酚类化合物. 同时对不同类别的化合物在二维气相色谱上的分布模式进行了研究. 结果表明, 全二维气相色谱飞行时间质谱的高分辨率非常适合于烟叶这类复杂体系的分离分析.     

二茂铁不同取代基对其电化学行为的影响

基于二茂铁不同取代基的氧化还原性,利用玻碳电极研究二茂铁及其醇类、醛类、羧酸类的电化学性质。通过循环伏安法探讨了取代基诱导效应和共轭效应对二茂铁电化学性质的影响,并用计时安培法测定了上述8种化合物的扩散系数,探讨了取代基与参数的相关性。     

整体柱在线固相微萃取-高效液相色谱同步富集检测水中的苯氧羧酸类除草剂

采用C18毛细管整体柱作为固相微萃取整体柱,构建在线固相微萃取-高效液相色谱联用系统,同步富集检测环境水样中的5种苯氧羧酸类除草剂。详细考察了联用系统运行条件对富集检测的影响。联用系统运行最佳参数为:固相微萃取整体柱长度20 cm,进样流速0.04 mL/min,进样13 min,洗脱流速0.02 mL/min,洗脱5 min。在最佳条件下,5种苯氧羧酸类除草剂的检出限为:9 μg/L (苯氧丙酸)、4 μg/L (2-(2-氯)-苯氧丙酸)、4 μg/L (2-(3-氯)-苯氧丙酸)、5 μg/L (2,4-二氯苯氧乙酸)、5 μg/L (2-(2,4-二氯苯氧基)丙酸)。与HPLC系统直接进样对比,联用系统对5种检测对象表现出优良的富集能力。5种苯氧羧酸类除草剂的回收率在79.0%~98.0%之间(RSD≤3.9%)。该方法成功应用于水样中5种苯氧羧酸类除草剂的检测,结果令人满意。     

“一锅法”制备氨基碳纳米管功能化磁性纳米粒子及其在谷物和蔬菜中苯氧羧酸类除草剂测定中的应用北大核心CSCD

有效萃取是分析复杂样品中苯氧羧酸类除草剂(PAs)残留的关键步骤。为此,该文利用“一锅法”水热技术快速、简便地制备了氨基碳纳米管功能化磁性纳米粒子(NH-CNTs@M)并作为磁固相萃取(MSPE)的萃取介质,用于萃取谷物和蔬菜样品中痕量PAs。研究利用多种手段对NH-CNTs@M的形貌、尺寸、磁性性质等进行了表征,结果表明FeO的粒径、氨基化碳纳米管的直径以及NH-CNTs@M的磁饱和值分别为30 nm、40 nm和44.2 emu/g。详细考察了制备条件和萃取参数对NH-CNTs@M/MSPE萃取性能的影响,结果表明,NH-CNTs@M/MSPE可通过π-π、疏水和氢键作用有效富集目标化合物,最佳萃取条件如下:吸附剂用量为30 mg,解吸溶剂为含2.0%(v/v)甲酸的乙腈溶液,吸附时间和解吸时间分别为8.0 min和3.0 min,基底pH值为6.0,不调节基底的离子强度。将NH-CNTs@M/MSPE与高效液相色谱-二极管阵列检测技术(HPLC-DAD)联用,建立了谷物和蔬菜中PAs的灵敏检测方法。谷物和蔬菜基质中苯氧羧酸类除草剂的检出限(LOD,S/N=3)分别为0.32~1.6μg/kg和0.53~1.6μg/kg,定量限(LOQ,S/N=10)分别为0.94~4.8μg/kg和1.6~4.8μg/kg。在两种实际样品中不同浓度下的加标回收率分别为73.1%~112%和72.3%~113%。与现有方法相比,所建方法具有萃取速度快、灵敏度高和环境友好等特点。     

咪唑二羧酸及其衍生物构筑配合物的研究进展

咪唑二羧酸类有机配体由于具有多个配位点以及多种配位模式,在构筑配位聚合物方面得到了广泛的研究与应用.由该类配体构筑的配合物种类繁多,结构新颖,迄今已合成了上百种.本文详细概括了咪唑二羧酸类配体的特点、配位模式、配体种类以及相应的配合物,并从烷基取代和芳香基取代两方面综述了这些配合物的发展及其研究现状,同时简述了这类配体构筑的配合物在光学、气体吸附、磁性、催化以及介电方面的性能,最后对这类配体的发展前景进行了展望.     

稀土-氨基多羧酸类配合物的分子结构及配位规律的研究

报道了稀土金属离子与一系列氨基多羧酸类配体形成配合物的分子结构和晶体结构. 讨论了稀土金属离子与氨基多羧酸类配体的配位规律, 证明了稀土金属离子像其他过渡金属离子一样, 与氨基多羧酸配体形成配合物的配位数和配位结构取决于稀土金属离子的离子半径, 电子结构和氧化态以及氨基多羧酸类配体的形状. 氨基多羧酸类配体是指氨基三乙酸(=nta), 乙二胺四乙酸(=edta), 反式-1,2-环己二胺四乙酸(= Cydta), 二乙三胺五乙酸(= dtpa)和三乙四胺六乙酸(=ttha).     

新型手性溶解剂的合成及手性识别研究

核磁共振手性溶解剂法是精确、快速地测定微量手性化合物ee(enantiomeric excess)值的方法之一.目前有许多关于手性溶解剂(CSAs)的文献报道,但适合于手性羧酸类对映体识别的CSAs仍较少.光学活性的胺常被用作测定手性羧酸的手性溶解剂,其中以α-苯乙胺的使用最为广泛,但有时因被测物的化学位移不等价值(△△δ)较小而使其应用受到限制.光学活性的胺与手性羧酸类对映体作用时,胺基与羧基的成盐作用是主客体相互作用的方式之一.我们结合这一特点设计合成了一类新型的手性溶解剂,通过1H NMR,MS,IR和元素分析对其进行了结构表征.该类化合物具有较好的溶解性能,我们将其作为手性溶解剂对外消旋的α-甲氧基苦杏仁酸和两种手性药物分子萘普森,布洛芬进行了识别研究,它们均表现出较好的手性识别效果.合成路线如下:     

一个实用的合成甾烯-3-羧酸Epristeride的方法

甾烯-3-溴化合物通过钯催化的一氧化碳插入反应被转化成为相应的甾烯-3-羧酸类化合物。从而为甾烯-3-羧酸Epristeride提供了一个实用的合成方法。     

稻米中13种苯氧羧酸类除草剂多残留的高效液相色谱-质谱测定

建立了高效液相色谱-质谱联用（HPLC—MS）选择离子监测（SIM）同时测定稻米中13种苯氧羧酸类除草剂多残留的方法。样品经过乙腈提取,盐酸酸化,SCX阳离子交换吸附剂分散固相萃取净化后,采用HPLC—MS测定。对13种苯氧羧酸类除草剂的液相色谱分离、样品前处理条件进行了详细的研究和优化,13种苯氧羧酸类除草剂在0．02～1．0mg／L范围内线性良好,相关系数为0．9954～0．9998。在0．05～1．0mg／kg范围内,平均添加回收率为77％～99％,相对标准偏差为0．9％～14．9％。     

Comparative molecular field analysis of chromatographic hydrophobicity indices for some coumarin analogs

The chromatographic hydrophobicity index (CHI) is an HPLC‐based parameter that provides reliable guidance in optimization of pharmacological efficiency and adsorption, distribution, metabolism and exertion (ADME) profile of drug candidates. In the present work, classical and three‐dimensional quantitative structure–property relationship (QSPR) models were developed for prediction of CHI values of some 4‐hydroxycoumarin analogs on immobilized artificial membrane column. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) as 3D–QSPR methods were performed to gain insight into the key structural factors affecting on the chromatographic hydrophobicity of interested chemicals. The calculated parameters of Q ², R ² and standard error were 0.545, 0.996 and 0.773 for CoMFA model and 0.815, 0.986 and 1.44 for CoMSIA model, respectively. The contour maps for steric fields of the CoMFA model illustrate that the hydrophobicity of chemicals will be higher when the positions of R6, R7 and R8 in the 4‐hydroxycuomarin ring are substituted by alkyl groups. Moreover, by the analysis of the plots of electrostatic fields, it was concluded that the CHI value greatly increases if one hydrogen on coumarin ring is substituted by the F, Cl, Br, OH or OCH₃ group.     

Three-dimensional quantitative structure-property relationship (3D-QSPR) models for prediction of thermodynamic properties of polychlorinated biphenyls (PCBs): enthalpy of vaporization

Three-dimensional Quantitative Structure-Property Relationship (QSPR) models have been derived using Comparative Molecular Field Analysis (CoMFA) to correlate the vaporization enthalpies of a representative set of polychlorinated biphenyls (PCBs) at 298.15 K with their CoMFA-calculated physicochemical properties. Various alignment schemes, such as inertial, as is, and atom fit, were employed in this study. The CoMFA models were also developed using different partial charge formalisms, namely, electrostatic potential (ESP) charges and Gasteiger-Marsili (GM) charges. The most predictive model for vaporization enthalpy (Delta(vap)H(m)(298.15 K)), with atom fit alignment and Gasteiger-Marsili charges, yielded r2 values 0.852 (cross-validated) and 0.996 (conventional). The vaporization enthalpies of PCBs increased with the number of chlorine atoms and were found to be larger for the meta- and para-substituted isomers. This model was used to predict Delta(vap)H(m)(298.15 K) of the entire set of 209 PCB congeners.     

Pharmacophore interactions analysis and prediction of inhibitory activity of 1,7-diazacarbazoles as checkpoint kinase 1 inhibitors: application of molecular docking, 3D-QSAR and RBF neural network

In the present study, we mainly focused on new synthesized 1,7-diazacarbazole derivatives (44 active molecules) as Chk1 inhibitors to build 3D-QSAR model. Comparative molecular field analysis (CoMFA) model with three principal components was developed. The relative contributions in building of CoMFA model were 64.41 % for steric field and 35.59 % for electrostatic field. R ² values for training and test sets of CoMFA model were 0.8724 and 0.7818, respectively, and squared correlation coefficient for leave-one-out cross-validation test (q ²) was 0.6753. To improve the predictive power, a new 3D-QSAR model was developed by using radial basis function network (RBFN) and score of CoMFA interactions energy values as input variables. Scores 1, 2 and 3 were used as input variables, and a RBFN model with seven centers and spread value equal to 95 was developed to create a nonlinear 3D-QSAR model. R ² values for training and test sets were 0.9613 and 0.8564, and q ² for leave-one-out cross-validation test was 0.9258. Docking of all molecules to 3DX ligand binding site of Chk1 receptor indicated six interactions as pharmacological interactions between compounds and binding site of receptors. These pharmacological interactions were hydrogen bonding with LEU-15 and GLU-85 in main chain and four van der Waals interactions with LEU-15, VAL-23, TYR-86 and LEU-137 in side chain. CoMFA contour plots were used to design new inhibitors, and inhibitory activity of each compound was predicted by using CoMFA and RBFN models.