Continuous Porous Aromatic Framework Membranes with Modifiable Sites for Optimized Gas Separation

Continuous microporous membranes are widely studied for gas separation, due to their low energy premium and strong molecular specificity. Porous aromatic frameworks (PAFs) with their exceptional stability and structural flexibility are suited to a wide range of separations. Main-stream PAF-based membranes are usually prepared with polymeric matrices, but their discrete entities and boundary defects weaken their selectivity and permeability. The synthesis of continuous PAF membranes is still a major challenge because PAFs are insoluble. Herein, we successfully synthesized a continuous PAF membrane for gas separation. Both pore size and chemistry of the PAF membrane were modified by ion-exchange, resulting in good selectivity and permeance for the gas mixtures H₂/N₂ and CO₂/N₂. The membrane with Br^? as a counter ion in the framework exhibited a H₂/N₂ selectivity of 72.7 with a H₂ permeance of 51844 gas permeation units (GPU). When the counter ions were replaced by BF₄^?, the membrane showed a CO₂ permeance of 23058 GPU, and an optimized CO₂/N₂ selectivity of 60.0. Our results show that continuous PAF membranes with modifiable pores are promising for various gas separation situations.     

Co3O4/UiO-66@α-Al2O3陶瓷膜对VOCs废气的分离催化性能

以α-Al₂O₃为支撑层, UiO-66为分离层, Co₃O₄为催化层, 构建了Co₃O₄/UiO-66@α-Al₂O₃陶瓷膜.对其形貌结构进行了表征, 并研究了其对挥发性有机物(VOCs)的分离催化性能. 结果表明, 该陶瓷膜对喷涂行业废气中苯与吡啶两种主要成分体现出良好的分离性, 透过侧的气体中吡啶与苯的摩尔浓度比值可由给料侧的1提高至17; 体系中引入臭氧后, 给料侧苯的浓度明显降低, 其去除率可达到89%. 透过侧的吡啶去除率仅为27%, 得到了较大程度的保留, 剩余的吡啶经收集后可进行单独的深度处理. Co₃O₄/UiO-66@α-Al₂O₃陶瓷膜在对喷涂行业废气中苯成分高效降解的同时, 能够有效解决喷涂行业废气处理过程中氮氧化物的排放问题, 有望成为喷涂行业废气预处理工艺的理想选择.     

基于共价有机骨架材料的磁固相萃取-超高效液相色谱-串联质谱法测定水中4种杀菌剂

杀菌剂在环境中长期富集后会引起土壤和植物病害,并能借助雨水或灌溉渗透到深层土壤和地下水中,威胁水体环境和人体健康。因此针对水中杀菌剂开发简单快速、高效灵敏的分析方法至关重要。该研究通过原位合成法制备了磁性共价有机骨架材料Fe₃O₄@TpBD,将其作为萃取吸附剂,富集环境水体中苯并咪唑杀菌剂(噻菌灵、麦穗宁、多菌灵)和有机硫杀菌剂(稻瘟灵)。利用Fe₃O₄@TpBD与杀菌剂之间的π-π共轭、氢键和静电作用进行吸附,结合超高效液相色谱-串联质谱法(UHPLC-MS/MS)进行检测,建立了测定水中4种痕量杀菌剂的分析方法。通过透射电子显微镜、X射线衍射及傅里叶变换红外光谱等方式对Fe₃O₄@TpBD进行表征,以证明材料的成功合成。对萃取条件进行一系列的优化(Fe₃O₄@TpBD的磁性比例及用量、水样pH、吸附时间、洗脱液的种类及体积、洗脱时间、NaCl含量),确定了最佳萃取条件。4种杀菌剂在3~1200 ng/L的范围内线性关系良好,线性相关系数均大于0.998,方法的检出限和定量限分别为0.06~0.28 ng/L和0.20~0.92 ng/L。在15、150和600 ng/L 3个加标水平下进行加标回收试验,日内和日间精密度分别为2.8%~10.0%和4.4%~15.7%。将该方法用于实际水样的检测,4种杀菌剂的加标回收率为77.1%~119.1%,在水库水中检测出多菌灵,含量为27.5 ng/L。该方法灵敏度高,准确度和精密度良好,操作简单,耗时短。     

Extraction of parabens by melamine sponge with determination by high-performance liquid chromatography

In the present study, we propose a novel method for the extraction of parabens in personal care products. A new, simple adsorptive material was obtained by combining metal-organic frameworks and melamine sponges using the adhesive property of polyvinylidene fluoride. This new material, metal-organic frameworks/melamine sponges, was found to be particularly suitable for solid-phase extraction. The structural characteristics of metal-organic frameworks/melamine sponges were first analyzed by scanning electron microscopy. Subsequently, solid-phase extraction was performed on sample solutions, and the extracted substances were then analyzed by high-performance liquid chromatography. Following optimization of important experimental conditions, excellent recovery rates were obtained. Our novel method was then applied to the extraction of four parabens (methylparahydroxybenzoates, ethylparahydroxybenzoates, propylparahydroxybenzoates, and butylparahydroxybenzoates) from real samples. The results yielded limits of detection of 0.26–0.41 ng/mL. The inter- and intra-day recoveries were 104.0–109.7% and 91.2–98.1%, respectively (relative standard deviation, <13.8%).     

Facile synthesis of a novel magnetic covalent organic frameworks for extraction and determination of five fungicides in Chinese herbal medicines

A novel magnetic covalent organic framework was synthesized via a one-step coating approach with solvothermal reaction employing 2,4,6-tris(4-aminophen-yl)-1,3,5-triazine and 2,4,6-triformylphloroglucinol as two building blocks by covalent bonding. The prepared magnetic covalent organic frameworks were properly characterized by different techniques and employed as adsorbents of magnetic solid-phase extraction. An analytical method was developed for the simultaneous determination of five fungicides in two Chinese herbal medicine samples via magnetic solid-phase extraction coupled to ultra high performance liquid chromatography with tandem mass spectrometry analysis. Under optimized magnetic solid-phase extraction conditions, the method exhibited satisfactory recoveries (74.0−109.6%) with relative standard deviations of 0.4−4.6%, low limits of detection (0.003−0.015 μg/kg), and good linearity (R² > 0.9960). Compared with the traditional extraction method, the proposed method required a lower amount of adsorbent (3 mg) and extraction time (5 min). The adsorbent also had favorable reusability (not less than eight times). Therefore, the magnetic covalent organic frameworks could be a promising adsorbent for the extraction and quantitation of fungicides in Chinese herbal medicines.     

In-situ grown metal organic framework synergistic system for the enantioseparation of three drugs in open tubular capillary electrochromatography

Metal organic frameworks have received great attention as the chiral stationary phase for racemic drug separation because of their fascinating structures and properties. However, the most homochiral metal organic frameworks were constructed by rare and precious chiral organic ligands. In this work, an achiral metal organic framework, together with a natural chiral selector carboxymethyl β-cyclodextrin built a synergistic separation system in the open tubular capillary electrochromatography. The novel coated columns were developed by inducing metal organic framework nanoparticles to grow on the imidazolyl functional capillary inner wall. The baseline separations of hydroxychloroquine, ofloxacin, and atenolol were achieved in the synergistic separation system. The effects of the concentration of chiral selector, pH, voltage, and the concentration of organic additives were studied. Compared with chiral selector auxiliary bare capillary, the resolutions of three drugs were remarkably improved. The relative standard deviations for the retention time of intraday (n = 6), interday (n = 6), and column-to-column were less than 2.1, 2.6, and 5.2%, respectively. These results demonstrate that affordable synergistic separation systems are prospective for racemic drug enantioseparation in capillary electrochromatography.     

Triple-Layered Metal-Organic Framework Hybrid for Tandem Response-Driven Enhanced Chemotherapy

The precise release of drugs is essential to improve cancer therapeutic efficacy. In this work, a tandem responsive strategy was developed based on a triple-layered metal-organic framework (MOF) hybrid. The MOF nanoprobe was stepwise fabricated with a telomerase-responsive inner, a pH-sensitive MOF filling and H₂O₂-responsive coordination complex shell of Fe³⁺ and eigallocatechin gallate (EGCG). In the tumor microenvironment, the shell was dissociated by endogenous H₂O₂ and simultaneously produced highly reactive hydroxyl radicals by a Fenton reaction. Meanwhile, the released EGCG could downregulate the expression of P-glycoprotein responsible for drug resistance. After the dissociation of the framework by protons, telomerase could trigger the release of the drug from the DNA duplex on the exposed inner shell. By integrating confined drug release, inhibited efflux pump and chemodynamic therapy, the all-in-one chemotherapy strategy was identified with enhanced therapeutic efficacy in drug-resistant cancer cells.     

UiO-66 and hcp UiO-66 Catalysts Synthesized from Ionic Liquids as Linker Precursors

Using ionic liquids (ILs) as linker precursors, the well-known metal-organic framework (MOF) UiO-66 (Universitetet i Oslo) and the recently reported MOF hcp UiO-66 (hexagonal closed packed) have been successfully synthesized and characterized. The advantage of the applied novel synthesis approach is an economically and environmentally benign work-up procedure, due to the better solubility of the IL. Additionally, the reactivity of the terephthalate anions is increased compared to terephthalic acid, resulting in faster MOF formation with an increased amount of defects in the MOF structure. In order to explore to the influence of defects on the catalytic performance, the cyclisation of citronellal to isopulegol was employed as test reaction. The activity of hcp UiO-66 and fcc UiO-66 (face centered cubic) is improved compared to other MOF or zeolite based catalysts, while the selectivity is similar.     

Advances in nucleic acid architectures for electrochemical sensing

Nucleic acid–based electrochemical sensors are ideally suited to the detection of molecular targets for which enzymatic detection or direct electrochemical oxidation – reduction reactions are not possible. Moreover, the versatility of nucleic acids in their ability to bind a great variety of target types, from small molecules to single-entity mesoscopic targets, makes them attractive receptors for the development of electrochemical biosensors. In this brief opinion piece, we discuss field advances from the past two years. We hope the works highlighted here will inspire the community to pursue creative designs enabling the detection of larger and more complex targets with a specific focus on analytical validation and translation into preclinical or clinical applications.