Fabrication of ZnO with tunable morphology through a facile treatment of Zn-based coordination polymers

The morphology and structure of zinc oxide(ZnO), one of the important semiconductors, are relevant to its properties and applications. The preparation of ZnO with tunable morphology and desired structure is an attractive topic in the field of material synthesis. This work reports a facile method for the synthesis of Zn O with controllable morphology and crystal orientation using Zn-based coordination polymer particles(Zn-CPP) as precursors. Using hydrothermal method, Zn-CPP with morphologies of microrod, nanoplate, flower-like, arrow-tipped microsheet, and square cylinder were successfully synthesized via the coordination between metal ions Zn2+ and organic ligand 1,4,5,8-naphthalenetetracarboxylic dianhydride in aqueous solution. Subsequent thermal treatment of the Zn-CPP successfully resulted in the formation of porous Zn O with similar morphology to Zn-CPP. It is also found that the Zn O with enhanced(002) orientation could be obtained from Zn-CPP with preferred(002) orientation. This strategy could be extended for the preparation of other metal oxides with desired shape and structure.     

Large‐Scale Fabrication of Polymer Microcavities with Adjustable Openings and Surface Roughness Regulated by the Polarity of both Seed Surface and Monomers

Polymer microcavities with adjustable openings and surface roughness are fabricated on a large scale via single‐hole poly(glycidyl methacrylate) (PGMA) swelling seed particles. The size of openings of these microcavities can be adjusted by changing the amount of hydrophilic monomer, and the degree of surface roughness is easily regulated relying on the adjustment of the polarity of monomer. Furthermore, the morphology of PGMA/poly(styrene‐methacrylic acid) (PGMA/P(S‐MAA)) microparticles from microcavity to erythrocyte shape is controlled by the polarity of seed surface. From transmission electron microscopy images of PGMA/P(S‐MAA) microparticles, a fresh polymer particle appears in the cavity. To confirm this phenomenon, thermal annealing process in dioxane/water solution is carried out. Considering the flexibility of polymers, the openings and closing of the prepared microparticles are regulated following the increase in volume ratio of dioxane/water. Ball‐in‐bowl‐shaped PGMA/P(S‐MAA) microparticles are further presented, which proves secondary nucleation of monomer in the polymerization stage.

     

A Redox‐Dependent Electrochromic Material: Tetri‐EDOT Substituted Thieno[3,2‐b]thiophene

Organic electrochromic materials change color rapidly under applied potential. A butterfly‐shaped compound, 5,5′,‐5″,‐5′″‐(thieno[3,2‐b]thiophene‐2,3,5,6‐tetrayl) tetrakis‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxine) (t‐EDOT‐TT) is synthesized for the first time and polymerized at different potentials via electropolymerization technique. By applying different polymerization potentials, the optical and electrochromic properties of this newly synthesized polymer can be tuned. Owing to the dependence of functional group position in the polymer structure on the redox potential, this polymer can be utilized in very interesting organic optoelectronic applications.

     

Metal-free catalytic enantioselective silylation of aromatic aldehydes in water

One-step access to chiral α-hydroxysilanes by metal-free catalytic enantioselective silylation of aromatic aldehydes in water was achieved for the first time.     

Minireview: Recent Advances in Surface-Enhanced Raman Scattering-Based Nucleic Acid Detection with Application to Pathogen Diagnosis

Surface-enhanced Raman scattering (SERS) is a promising analytical tool in nanoscale detection because of its high sensitivity and selectivity. This review focuses on recent advances in SERS-based detection of DNA and RNA. First, nanostructure-based SERS-active substrates are introduced. Using label-free and labeled SERS, target biomolecules such DNA, RNA and microRNA have been successfully detected. Finally, applications in pathogen diagnosis are discussed. The prospects and challenges of SERS-based bioanalysis are highlighted.     

Thapsigargin的全合成研究进展

Thapsigargin是一类从地中海植物毒胡萝卜(thapsia garganica)中分离得到的结构复杂的高氧化态倍半萜内酯,其对肌浆-内质网Ca~(2+)-ATP泵(SERCAs)具有不可逆的抑制作用,抑制浓度达纳摩尔级别(KD=0.4 nmol/L)。Thapsigargin因其独特的结构和良好的生物活性而备受有机合成化学家的广泛关注。在合成中,立体选择性地构建该分子cis-5/7/5稠环体系以及多个手性中心是极具挑战性的。本文综述了该分子近二十年来的全合成研究进展。     

固体进样总有机碳分析仪校准方法

建立固体进样总有机碳分析仪的校准方法.根据仪器原理及使用情况,选取线性、示值误差、重复性作为仪器的主要计量特性,并探讨各个计量特性的校准方法.用该方法对某型号的仪器进行校准,得线性相关系数为0.998,示值误差为0.86％,重复性为0.39％,并对示值误差测量结果不确定度进行了评定,扩展不确定度为0.94％(k=2)....     

A new fluorescent quinoline derivative toward the acid-responsivity in both solution and solid states

In this article, an acid-responsive luminescent material, 1,4-di(quinoline-6-yl)buta-1,3-diyne (DQBD) is designed and synthesized. Upon different pH values, gradual changes of fluorescence colors for DQBD in both solution and solid phases are demonstrated due to the protonation effect. Moreover, such responsive characteristics can also be reversible, suggesting DQBD as a promising fluorescent material with great potential for reusable- and accurate-pH sensors in the future.     

Vacancy Engineering of Iron-Doped W18O49 Nanoreactors for Low-Barrier Electrochemical Nitrogen Reduction

The electrochemical nitrogen reduction reaction (NRR) is a promising energy-efficient and low-emission alternative to the traditional Haber–Bosch process. Usually, the competing hydrogen evolution reaction (HER) and the reaction barrier of ambient electrochemical NRR are significant challenges, making a simultaneous high NH₃ formation rate and high Faradic efficiency (FE) difficult. To give effective NRR electrocatalysis and suppressed HER, the surface atomic structure of W₁₈O₄₉, which has exposed active W sites and weak binding for H₂, is doped with Fe. A high NH₃ formation rate of 24.7 μg h⁻¹ mg_cat⁻¹ and a high FE of 20.0 % are achieved at an overpotential of only −0.15 V versus the reversible hydrogen electrode. Ab initio calculations reveal an intercalation-type doping of Fe atoms in the tunnels of the W₁₈O₄₉ crystal structure, which increases the oxygen vacancies and exposes more W active sites, optimizes the nitrogen adsorption energy, and facilitates the electrocatalytic NRR.     

Highly antibacterial hydrogels prepared from amino cellulose,dialdehyde xylan,and Ag nanoparticles by a green reduction method

Cellulose - Hydrogels with antibacterial activity have attracted more and more attention in the wound dressing area. Here, we developed antibacterial hydrogels directly from cellulose, xylan, and...