高效液相色谱-电感耦合等离子体质谱联用技术用于环境中元素形态分析的最新进展

综述了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术在环境科学中的应用情况.参考过去十年内的国内外文献,从方法学的角度论述了HPLC联用ICP-MS技术的发展,重点探讨了该技术在环境领域,尤其是在元素形态分析(包括生物学,生物无机化学和生物医学)中的应用.     

液相色谱串联质谱法测定养殖水体中孔雀石绿及其代谢物

研究利用液相色谱-串联质谱(LC-ESI-MS/MS)测定水产品养殖水体中孔雀石绿及其代谢物隐性孔雀石绿的方法.通过一系列实验对样品前处理条件进行了优化研究,养殖水样经乙酸酸化,净化后,采用HPLC-ESI-MS/MS检测分析.在多反应监测模式(MRM)下,外标法定量,定量限均为0.5μg/kg.在0.5～50μg/L...     

Synthesis and molecular structure of 7<Emphasis Type="Italic">H</Emphasis>-12-oxa-3,7-diazapleiadene-substituted 1,3-tropolones

An acid-catalyzed reaction of substituted 2-methyl-7H-12-oxa-3,7-diazapleiadenes with 1,2-benzoquinones leads to 7H-12-oxa-3,7-diazapleiadene-substituted 1,3-tropolones. Molecular structure of 5,7-di(tert-butyl)-2-[9,11-di(tert-butyl)-4-methyl-7H-12-oxa-3,7-diazapleiaden-2-yl]-4-nitro-1,3-tropolone was established by X-ray crystallography. Energy and structural characteristics of isomeric 5,7-di(tert-butyl)-2-[9,11-di(tert-butyl)-4-methyl-7H-12-oxa-3,7-diazapleiaden-2-yl]-4-nitro-1,3-tropolones in the gaseous phase and a polar solution were studied by the PBE0/6-31G** method.     

The electronic spectra of the sandwich stacked PFBT: a theoretical study

Stacked models that include 9,9'-bis(6'-N,N,N-trimethylammonium)hexyl]fluorene-co-alt-4,7-(2,1,3-benzothiadiazole)dibromide (F(BT)F) monomer sandwiched between two stacked 2,1,3-benzothiadiazole (BT) units were explored using theoretical approaches. Molecular structures and the optical characteristics of the investigated species were investigated at the M06-2X/6-311G(d,p)//TD-M06-2X/6-311G(d,p) level of theory. In all models, the electronic excitation to the lowest singlet ππ* excited state (S1(ππ*)) is governed by the highest occupied molecular orbital to lowest unoccupied molecular orbital (HOMO → LUMO) transitions. The obtained results suggest that stacking interaction might have only minor effects on the transition energy for both absorption and emission processes. Instead, the reduction in the excitation energy of the stacked complexes should be attributed to the dipole-dipole interaction. The larger the interaction energy of the stacked models, the bigger the observed differences between absorption-emission energies. The presence of the solvation medium with small dielectric constant may increase the absorption-emission energy differences. It is expected that the largest absorption-emission shift can be observed in the benzene solution.     

Theoretic calculation for understanding the oxidation process of 1,4-dimethoxybenzene-based compounds as redox shuttles for overcharge protection of lithium ion batteries

The effect of substituents on the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene was understood with a theoretical calculation based on density functional theory (DFT) at the level of B3LYP/6-311+G(d). It is found that the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene is 4.13 V (vs Li/Li(+)) and can be changed from 3.8 to 5.9 V (vs Li/Li(+)) by substituting electron-donating or electron-withdrawing groups for the hydrogen atoms on the aromatic ring. These potentials are in the range of the limited potentials for the lithium ion batteries using different cathode materials, and thus the substituted compounds can be selected as the redox shuttles for the overcharge prevention of these batteries. The oxidation potential of 1,4-dimethoxybenzene decreases when the hydrogen atoms are replaced with electron-donating groups but increases when replaced with electron-withdrawing groups. The further oxidation of these substituted compounds was also analyzed on the basis of the theoretic calculation.     

Direct acetoxylation and etherification of anilides using phenyliodine bis(trifluoroacetate)

Treatment of various anilides with 1.5 equiv. of phenyliodine bis(trifluoroacetate) (PIFA) and 1.0 equiv. of BF(3)·OEt(2) in AcOH at room temperature afforded the corresponding para-acetoxylated products with high regioselectivity. In addition, this reaction could be expanded to the etherification of anilides. In the presence of 2.0 equiv. of PIFA and 2.0 equiv. of BF(3)·OEt(2), the reaction of anilides with alcohols provided the corresponding para-etherified products in good yields.     

Elaboration of vinblastine hybrids using a reactive in situ generated N-carboxyanhydride

Hybrids of vinblastine and phomopsin, designed by a molecular modelling study, were elaborated in order to target tubulin. The key step of the synthesis (fragmentation and insertion of vindoline) was mediated by an internal N-carboxyanhydride (or O-acylcarbamate). This reaction was diastereospecific and addition of silver salts could reverse the diastereoselectivity. Even if the synthesized compounds are inactive, this synthesis represents an original example of a C-N fragmentation mediated by a N-carboxyanhydride.     

Cationic nucleolipids as efficient siRNA carriers

We synthesized five novel uridine-based cationic nucleolipids, introducing basic amino acid residues at the 5' position of uridine, through 1,3-dipolar cycloaddition, and hydrophobic alkyl moieties at the 2' and 3' positions, through carbamate linkages. Their lipoplexes delivered siRNAs efficiently to cells, in vitro, without any severe toxicity.     

Coordination-perturbed single-molecule magnet behaviour of mononuclear dysprosium complexes

By changing the ratio of reactants, two mononuclear Dy complexes, [Dy(phen)(acac)(3)] (1) and [Dy(phen)(2)(NO(3))(2)(acac)]·H(2)O (2) have been synthesized and structurally characterized. In 1, a Dy atom bearing square-antiprism coordination geometry exhibits SMM behaviour, while compound 2 with a bicapped-square-antiprism geometry does not show such SMM properties. The different magnetic behaviours seen in 1 and 2 are probably due to a different coordination environment and ligand field around the Dy(III) ions. The results proved the important influence of the structural environment of a SMM on its magnetic behaviour.     

Size-dependent catalysis by DABCO-functionalized Zn-MOF with one-dimensional channels

Lewis basic DABCO-functionalized 3D-like metal-organic framework, Zn-MOF, catalyzes nitroaldol (Henry) reaction of 4-nitrobenzaldehyde with nitroalkanes in a size-dependent manner. Small nitroalkanes give rise to higher conversion than larger ones. This MOF-based heterogeneous catalyst is very robust and can be recycled several times without losing its activity.