Formation of a novel 1D supramolecule [HgCl2(ptz)]2.HgCl2 (ptz = phenothiazine): a new precursor to submicrometer Hg2Cl2 rods

A novel supramolecule [HgCl(2)(ptz)](2).HgCl(2) (ptz = phenothiazine) with uncoordinated inorganic salt HgCl(2) presented in a 1D chain was first prepared and then successfully applied as a new precursor in the preparation of submicrometer Hg(2)Cl(2) rods. Single crystal X-ray analysis showed that the 1D chain structure is stabilized by hydrogen bonds between adjacent chains and the coordination mode of the ligand phenothiazine is unusual with large steric inhibition other than the chain directions. The results revealed that the particular chain structure plays a significant role in the formation of the Hg(2)Cl(2) rods.     

Hydrothermal preparation of hybrid carbon/silica monolithic capillary column for liquid chromatography

A simple, easy and economical approach for the preparation of a hybrid carbon/silica monolithic capillary column was described for the first time by using silica monolith as framework in combination with hydrothermal carbonization at 180°C. During the preparation process, formamide was introduced to the reaction solutions to reduce the dissolution rate of monolithic silica skeleton and its optimal concentration was 1.5 M. Fourier transform infrared spectrometry, scanning electron microscopy, energy dispersive X‐ray spectrometry, and inverse size exclusion chromatography were carried out to characterize the as‐prepared column. The results demonstrated that carbon spheres ranging from 150 to 1000 nm were successfully attached to the surface of silica skeleton. The prepared hybrid carbon/silica column had a permeability of 4.4 × 10^?14 m². Chromatographic performance of the column was evaluated by separation of various compounds including alkylbenzenes, nucleosides and bases, and aromatic acids. The column exhibited an efficiency of 75 000 plates/m for butylbenzene at the optimal linear velocity of 0.23 mm/s. The successful separation of these compounds and the study on mechanism indicated that the column can be applied in mixed‐mode chromatography.     

A new perspective for effect of S and Cu on the photocatalytic activity of S,Cu-codoped nano-TiO2 under visible light irradiation

Sulfur and copper codoped TiO₂ nanoparticles were prepared by sol-hydrothermal process. And the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra analysis, scanning electron microscopy, Brunauer Emmett Teller analysis, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectra and X-ray fluorescence analysis. It was found that the S, Cu-codoped TiO₂ became amorphous with the increase of Cu content, and copper on the surface of TiO₂ existed in the oxidation state of Cu(II) while S in the form of S⁶⁺ species. And the codoped particles had higher surface area, smaller particle size, stronger spectral response in visible region compared with pure TiO₂. The effects of doping amount in a wide range, catalyst dosage, and recycle on the photocatalytic activity of the codoped catalysts were investigated with Acid Orange 7 as the model compound under visible light illumination (λ > 447 nm). The results showed that S (2.0 %), Cu (5.0 %) codoped TiO₂ had the highest visible light photocatalytic activity and good reusability performance. The kinetic study showed that this photocatalytic process coincided with the Langmuir–Hinshelwood pseudo first order reaction model.     

Application of magnetic graphitic carbon nitride nanocomposites for the solid‐phase extraction of phthalate esters in water samples

Magnetic graphitic carbon nitride nanocomposites were successfully prepared in situ and used to develop a highly sensitive magnetic solid‐phase extraction method for the preconcentration of phthalate esters such as di‐n‐butyl phthalate, butyl phthalate, dihexyl phthalate, and di‐(2‐ethyl hexyl) phthalate from water. The adsorption and desorption of the phthalate esters on magnetic graphitic carbon nitride nanocomposites were investigated and the parameters affecting the partition of the phthalate esters, such as adsorption, desorption, recovery, were assessed. Under the optimized conditions, the proposed method showed excellent sensitivity with limits of detection (S/N = 3) in the range of 0.05–0.1 μg/L and precision in the range of 1.1–2.6% (n = 5). This method was successfully applied to the analysis of real water samples, and good spiked recoveries over the range of 79.4–99.4% were obtained. This research provides a possibility to apply this nanocomposite for adsorption, preconcentration, or even removal of various carbon‐based ring or hydrophobic pollutants.     

Predictable site-selective radical fluorination of tertiary ethers

In this communication,we disclose the first example of metal-free and site-selective radical fluorination of readily available tertiary alkyl ethers,enabled by synergistic photocatalysis and organocatalysis.This catalytic combination allows for exclusive fluorination of tertiary C–O bonds under mild conditions even in the presence of competing reaction sites.The excellent functional group tolerance affords valuable access to sterically hindered alkyl fluorides through late-stage modification of complex molecules.The successful use of tertiary alkyl ethers in radical fluorination enhances the structural diversity of aliphatic fluorides that can be derived from naturally abundant alcohols.     

Reversibly Switching the Charge State and Adsorption Location of A Single Potassium Atom on Ultrathin CuO Films

Potassium (K) cations are spontaneously formed upon thermal deposition of low‐coverage K onto an ultrathin CuO monolayer grown on Cu(110) and they were explored by low‐temperature scanning tunneling microscopy (STM) and X‐ray photoemission spectroscopy. The formed K cations are highly immobile and thermally stable. The local work function around an individual K cation decreases by 1.5±0.3 eV, and a charging zone underneath it is established within about 1.0 nm. The cationic and neutral states of the K atom are switchable upon application of an STM bias voltage pulse, which is simultaneously accompanied by an adsorption site relocation.     

利用小角/广角X射线散射联用及一维相关函数分析研究聚(ε-己内酯)片晶的形态

用小角/广角X射线散射(SAXS/WAXS)联用的实验方法考察了等温结晶温度(Tc)和等温时间对聚(ε-己内酯)(PCL)片晶形态的影响.根据WAXS数据计算了PCL的重量结晶度,进而求得其体积结晶度Vc(WAXS).在不同Tc下结晶的PCL样品的Vc(WAXS)均略高于50%.对SAXS谱线做一维相关函数(1DCF)分析,得到了PCL的片晶长周期(LP)和无定形层厚度(La).通过比较WAXS及SAXS的数据分析结果,认为PCL晶体需用"三相模型"予以描述,其过渡层厚度(E)约为LP的15%～18%,对片晶形态具有重要影响.随着Tc升高,PCL晶体的Lc、La及E均逐渐增大,但Lc的变化率最大,这使得结晶度上升.在50℃等温结晶不同时间,发现Lc随延长时间显著增加,而La及E则不断减小.等温10天后,PCL晶体的SAXS谱线上可观察到5级散射,表明片晶相当完善.     

米氏酸在杂环化合物合成中的应用研究进展

综述了近年来米氏酸在杂环化合物合成中的应用,涉及到吡喃环、吡啶环、呋喃环、吡咯环、噁唑环和异噁唑环重要杂环的形成.大多具有反应条件温和、便利、产率较高等优点.     

Covalent selection of the thiol proteome on activated thiol sepharose: A robust tool for redox proteomics

Protein thiols contribute significantly to antioxidant defence and selective oxidation of cysteines is important in signal transduction even in sub-stress scenarios. However, cysteine is the second rarest residue in proteins and it can be difficult to target low-abundance thiol (-SH)-containing proteins in proteomic separations. Activated thiol sepharose (ATS) allows covalent selection of -SH-containing proteins which can then be recovered by reduction with mercaptoethanol or dithiothreitol. This is a robust method for enriching -SH-containing proteins. We have used ATS to estimate the percentage (by weight) of thiol-containing proteins in cell extracts from a range of biological sources: a bacterium, Escherichia coli; a fungus, Trichoderma harzianum; and a bivalve mollusc Mytilus edulis. -SH-containing proteins account for 2.52% (E. coli), 1.4% (T. harzianum) and 1.4% (M. edulis) of total protein. Exposure to pro-oxidants did not materially alter these values. On removal of low M_r thiols such as glutathione, the values for M. edulis did not significantly change but those for T. harzianum increased threefold. The two-dimensional electrophoresis profiles of ATS-selected proteins for each organism were compared in control and pro-oxidant-exposed preparations. This revealed that some proteins present in controls were absent in pro-oxidant-treated extracts which we attribute to thiol oxidation. ATS has significant potential in enrichment for -SH-containing proteins in redox proteomics.     

Chiral separation and determination of ofloxacin enantiomers by ionic liquid-assisted ligand-exchange chromatography

A simple and accurate method for the separation and determination of ofloxacin enantiomers was developed by ionic liquid-assisted ligand-exchange high performance liquid chromatography. Both achiral and chiral ionic liquids were tested for their efficiency of ofloxacin enantiomeric separation. The effects of ligands, concentration of metal ion, organic modifier, pH of the mobile phase, and temperature were also investigated and evaluated. Optimal conditions were obtained on a conventional C(18) column, where the mobile phase consisted of methanol/water (20 : 80, v/v) (containing 4.0 mmol L(-1) amino acid ionic liquid and 3.0 mmol L(-1) copper sulfate) at a flow rate of 0.5 mL min(-1). Under this condition, the ofloxacin enantiomers could be baseline separated within 14 minutes; the proposed method was used to analyze different commercial ofloxacin medicines.