Large‐scale production of well‐dispersed submicro ZrB2 and ZrC powders

ZrB₂ and ZrC powders were synthesized via metallothermic reduction route using ZrO₂, B/C, and Mg as raw materials. Low packing density of the green mixture and high heating temperature of the furnace are crucial for the formation of well‐dispersed submicro powders. Optimum reaction time helped achieve good crystallization and high purity. The as‐prepared samples were characterized by XRD, FESEM, TEM, and particle size analyzer. Results showed that well‐dispersed ZrB₂ powders with mean particle size of 0.534 μm and ZrC powders with mean particle size of 0.376 μm can be obtained. Oxygen content can be controlled lower than 1.0 wt%. The bench‐scale output is about 10 kg/d.     

Mechanochemical Friedel–Crafts Alkylation—A Sustainable Pathway Towards Porous Organic Polymers

This study elucidates an innovative mechanochemical approach applying Friedel–Crafts alkylation to synthesize porous covalent triazine frameworks (CTFs). Herein, we pursue a counterintuitive approach by utilizing a rather destructive method to synthesize well-defined materials with intrinsic porosity. Investigating a model system including carbazole as monomer and cyanuric chloride as triazine node, ball milling is shown to successfully yield porous polymers almost quantitatively. We verified the successful structure formation by an in-depth investigation applying XPS, solid-state NMR and FT-IR spectroscopy. An in situ study of pressure and temperature developments inside the milling chamber in combination with two-dimensional liquid-state NMR spectroscopy reveals insights into the polymerization mechanism. The versatility of this mechanochemical approach is showcased by application of other monomers with different size and geometry.     

Nonmigrating Equivalent Substitutes for PVC/DOP Formulations as Shown by a TG Study of PVC with Covalently Bound PEO–PPO Oligomers

Monoamino functionalized ethylenoxide (EO)/propylenoxide oligomers (Jeffamine) are linked chemically to poly(vinyl chloride) (PVC) using trichlorotriazine chemistry in order to prepare nonmigrating internally plasticized materials. The dependence of the plasticizer efficiency on both the number of anchoring points to the chains and the PVC/plasticizer compatibility is investigated using oligomers of different molecular weight and hydrophilic–hydrophobic balance. Hydrophilic oligomers (containing predominantly EO) of molecular weights between 2000 and 5000 g mol⁻¹ exhibit excellent plasticizer efficiency, nearly identical to di‐2‐ethylhexylphthalate (DOP) in conventional PVC/DOP mixtures and may therefore be used as nonmigrating equivalents for DOP.

     

β-Cyclodextrin covalent organic framework supported by polydopamine as stationary phases for electrochromatographic enantioseparation

In this work, a new open-tubular capillary electrochromatography (OT-CEC) column was prepared using β-cyclodextrin covalent organic framework (β-CD COF) as a stationary phase. Polydopamine was used to assist fabrication of β-CD COF on an inner wall of a fused-silica capillary. The coating layer on the capillary was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electroosmotic flow (EOF) was also studied to evaluate the variation of the inner wall of immobilized columns. Furthermore, the chiral separation effectiveness of the fabricated capillary column was evaluated by CEC using enantiomers of several related proton pump inhibitors as model analytes, including omeprazole, lansoprazole, pantoprazole and tenatoprazole. The effects of bonding time and concentration of β-CD COF, the type, concentration and pH of buffer, applied voltage were investigated to obtain satisfactory enantioselectivity. In the optimum conditions, the enantiomers of four analytes were resolved within 15 min with resolutions of 1.63–2.62. The relative standard deviation values for migration times and resolutions of the analytes representing intraday and interday were less than 6.75% and 4.24%, respectively. The results reveal that β-CD COF has great potential as chiral-stationary phases for enantioseparation in CEC.     

Amino functionalized magnetic covalent organic framework for magnetic solid-phase extraction of sulfonylurea herbicides in environmental samples from tobacco land

An amino-functionalized magnetic covalent organic framework composite TpBD-(NH₂)₂@Fe₃O₄ (Tp=Tp1,3,5-triformylphloroglucinol, BD-(NH₂)₂ is 3,3',4,4'-biphenyltetramine) was prepared by post-synthesis modification. Due to its abundant benzene rings and amino groups, large specific surface area and porous structure, the prepared TpBD-(NH₂)₂@Fe₃O₄ exhibits high extraction efficiency toward sulfonylurea herbicides. Based on this, a new method of magnetic solid-phase extraction with TpBD-(NH₂)₂@Fe₃O₄ as the sorbent combined with high-performance liquid chromatography and ultraviolet detection was developed for trace analysis of sulfonylurea herbicides in environmental water, soil and tobacco leaves samples from tobacco land. Under the optimized conditions, the limits of detection within 0.05–0.14 μg/L were achieved with a high enrichment factor of 217-260-fold, and the relative standard deviations were 4.9–7.5% (n = 7, c = 0.5 μg/L). The linear range was around three orders of magnitude with the square of correlation coefficient higher than 0.9936. The method was applied to analyze five sulfonylurea herbicides in the environmental water, soil, and tobacco leave samples collected from tobacco land. No sulfonylurea herbicides were detected in these samples. The recoveries of target sulfonylurea herbicides in spiked environmental water, soil, and tobacco leaf samples were found in the range of 90.7–104, 70.7–99.0, and 59.3–97.8%, respectively. The results illustrate that the established TpBD-(NH₂)₂@Fe₃O₄-magnetic solid-phase extraction- high-performance liquid chromatography–ultraviolet detection method is efficient for the analysis of trace sulfonylurea herbicides in environmental samples.     

Room temperature fabrication of magnetic covalent organic frameworks for analyzing sulfonamide residues in animal-derived foods

A magnetic solid phase extraction method based on magnetic covalent organic frameworks (TpBD@Fe₃O₄; 2,4,6-triformylphloroglucinol (Tp) and benzidine (BD)) combined with high performance liquid chromatography has been developed to detect the sulfonamides including sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxazole in milk and meat. TpBD@Fe₃O₄ were synthesized at room temperature under mild reaction conditions with a simple and rapid operation. The TpBD@Fe₃O₄ exhibited higher extraction efficiency because of the π–π and electrostatic interactions between the benzene ring structure of the TpBD and the sulfonamide molecules. The extraction conditions including the dosage of adsorbents, the type and dosage of eluent, the elution time, and the pH of the sample solution were fully optimized. The detection results showed good linearity over a wide range (50–5 × 10⁴ ng/mL) and low detection limits (3.39–5.77 ng/mL) for the sulfonamide targets. The practicability of this magnetic solidphase extraction-high-performance liquid chromatography method was further evaluated by analyzing milk and meat samples, with recoveries of the targets of 71.6–110.8% in milk and 71.9–109.7% in pork. The successful detection of sulfonamides residues has demonstrated the TpBD@Fe₃O₄ excellent practical potential for analyzing pharmaceutical residues in animal-derived foods.     

Recent trends on the implementation of reticular materials in column-centered separations

Advances in the development of column-based analytical separations are strongly linked to the development of novel materials. Stationary phases for chromatographic separation are usually based on silica and polymer materials. Nevertheless, recent advances have been made using porous crystalline reticular materials, such as metal-organic frameworks and covalent organic frameworks. However, the direct packing of these materials is often limited due to their small crystal size and nonspherical shape. In this review, recent strategies to incorporate porous crystalline materials as stationary phases for liquid-phase separations are covered. Moreover, we discuss the potential future directions in their development and integration into suitable supports for analytical applications. Finally, we discuss the main challenges to be solved to take full advantage of these materials as stationary phases for analytical separations.     

基于共价有机框架的电化学生物传感器在生物样品检测中的应用

共价有机框架材料(Covalent Organic Frameworks, COFs)是一种具有纳米级结构有序性的二维或三维有机结晶材料, 具有高度周期性和可修饰性等结构优点. 基于COFs制备的电化学生物传感器具有灵敏度高、特异性强、重复性好等特点, 在检测生物样品方面具有广阔前景. 本综述简要概述了COFs的合成方法与策略、电化学生物传感器的介绍与分类以及COFs在电化学生物传感检测生物样品领域的应用. 最后本综述对COFs材料在生物传感领域的技术瓶颈与未来的发展方向进行了总结与讨论.     

Shape‐Controlled Synthesis and Self‐Sorting of Covalent Organic Cage Compounds

The directional bonding approach is a powerful tool to rationally control both shape and stoichiometry of three‐dimensional objects built from rigid building blocks under dynamic covalent conditions. Co‐condensation of catechol‐functionalized tribenzotriquinacene derivatives which have 90° angles between the reactive sites and diboronic acids with bite angles of 60°, 120°, and 180°, led to the efficient formation of, respectively, bipyramidal, tetrahedral, or cubic covalent organic cage compounds in a predictable manner. Investigations on the self‐sorting of ternary mixtures containing two competitive boronic acids revealed either narcissistic or social self‐sorting depending on the stability of the segregated cages relative to feasible three‐component assemblies.     

Dynamic Expression of DNA Complexation with Self‐assembled Biomolecular Clusters

We report herein the implementation of a dynamic covalent chemistry approach to the generation of multivalent clusters for DNA recognition. We show that biomolecular clusters can be expressed in situ by a programmed self‐assembly process using chemoselective ligations. The cationic clusters are shown, by fluorescence displacement assay, gel electrophoresis and isothermal titration calorimetry, to effectively complex DNA through multivalent interactions. The reversibility of the ligation was exploited to demonstrate that template effects occur, whereby DNA imposes component selection in order to favor the most active DNA‐binding clusters. Furthermore, we show that a chemical effector can be used to trigger DNA release through component exchange reactions.