具有高气态碘吸附的二维介孔共价有机框架

合成了一种新型的二维介孔共价有机框架(COF)材料JUC-573.粉末X射线衍射、氮气吸附-脱附和热重等表征结果表明合成的COF材料具有高结晶度、高比表面积以及良好的热稳定性.在333 K、常压条件下,该材料表现出优异的碘吸附能力,且吸附量高达4.15 g/g.这是由于在JUC-573中规则定向的垂直一维介孔孔道能够有效地避免碘吸附后的堵塞,从而优化了材料的吸附能力. JUC-573可多次循环用于气态碘的捕获且保持几乎不变的吸附量.     

Thiophene-based covalent organic frameworks for highly efficient iodine capture

Development of adsorbent materials for highly efficient iodine capture is high demand from the perspective of ecological environment and human health. Herein, the two kinds of thiophene-based covalent organic frameworks (COFs) with different morphologies were synthesized by solvothermal reaction using thieno[3,2-b]thiophene-2,5-dicarbaldehyde (TT) as the aldehyde monomer and tri(4-aminophenyl)benzene (PB) or tris(4-aminophenyl)amine (PA) as the amino monomer (denoted as PB-TT COF and PA-TT COF) and the as-prepared two heteroatoms-rich COFs possessed many excellent properties, including high thermal stability and abundant binding sites. Among them, PB-TT COF exhibited ultra-high iodine uptake up to 5.97 g/g in vapor, surpassing most of adsorbents previously reported, which was ascribed to its high specific surface (1305.3 m²/g). Interestingly, PA-TT COF with low specific surface (48.6 m²/g) showed good adsorption ability for iodine in cyclohexane solution with uptake value of 750 mg/g, which was 2.38 times higher than that obtained with PB-TT COF due to its unique sheet-like morphology. Besides, the two COFs possessed good reusability, high selectivity and iodine retention ability. Based on experimental results, the adsorption mechanisms of both COFs were studied, revealing that iodine was captured by the physical-chemical adsorption. Furthermore, the both COFs showed excellent adsorption ability in real radioactive seawater treated safely, demonstrating their great potential in real environment.     

A Two-dimensional Dual-pore Covalent Organic Framework for Efficient Iodine Capture

Effectively capturing volatile radioiodine generated during the nuclear fission process is considered to be a safe way to the utilization of nuclear power. Here we report a new two-dimensional covalent organic framework(2D COF), ETTA-PyTTA-COF, as a highly efficient iodine adsorbent, which is constructed through the condensation reaction between 4,4’,4’’,4’’’-(ethene-1,1,2,2-tetrayl)-tetrabenzaldehyde(ETTA) and 1,3,6,8-tetrakis(4-aminophenyl)pyrene(PyTTA). The ETTA-PyTTA-COF possesses a permanent 1D channel porous structure with a high Brunauer-Emmet-Teller(BET) surface area of 1519 m²/g and excellent chemical and thermal stability. It shows ultrahigh iodine adsorption capability, which can reach up to 4.6 g/g in vapor owing to its high BET surface area, large π-conjugated structure and plenty of imine groups in the skeleton of the COF as effective iodine sorption sites.     

偶氮苯功能化的光响应共价有机框架材料

通过后修饰的方法,在共价有机框架(COFs)材料JUC-500的孔道中引入光敏性的偶氮苯小分子,合成了具有光热刺激响应的共价有机框架材料JUC-501.在紫外线和加热作用下,孔道中的偶氮苯会发生可逆的顺-反异构变化,对染料污染物甲基橙(MO)表现出优异的可逆吸附与释放性能.     

一种高比表面积共价有机框架材料的合成及药物缓释性能

合成了一种具有较高比表面积(S_BET=1804 m ²/g)的新型二维共价有机框架(COF)材料(JUC-516), 并将其应用于模拟人体体液(SBF)中模拟动物体内的药物缓释, 取得了较理想的效果. 通过Materials Studio模拟、 粉末X射线衍射(PXRD)、 N₂吸附-脱附分析、 扫描电子显微镜(SEM)及傅里叶变换红外光谱(FTIR)等方法表征了所得COF材料的结构, 证实JUC-516是一种基于AA堆积hcb拓扑、 具有高结晶度和球状形貌的共价有机框架材料.     

基于四硫富瓦烯的无金属共价有机框架材料用于高效电催化析氧反应

共价有机框架(COFs)在电催化析氧反应(OER)中的应用得到了广泛的关注。然而,大多数无金属共价有机框架(COFs)的导电性较差,不利于OER反应。四硫富瓦烯(TTF)是一种良好的电子供体,具有快速的电子转移能力,将TTF整合到共价有机框架骨架中将有助于电子的转移。在此,我们报道了一种基于四硫富瓦烯的二维无金属共价有机框架材料,JUC-630。与不含四硫富瓦烯的同类材料(Etta-Td COF)相比,JUC-630具有较低的过电位(400 mV)和塔菲尔斜率(104 mV∙dec⁻¹)。本研究提出了合理设计功能基元的策略,这有助于大大提高COF材料的OER催化活性。     

Three-dimensional microporous and mesoporous covalent organic frameworks based on cubic building units

Covalent organic frameworks (COFs) have attracted extensive interest due to their unique structures and various applications. However, structural diversities are still limited, which greatly restricts the development of COF materials. Herein, we report two unusual cubic (8-connected) building units and their derived 3D imine-linked COFs with bcu nets, JUC-588 and JUC-589. Owing to these unique building blocks with different sizes, the obtained COFs can be tuned to be microporous or mesoporous structures with high surface areas (2728 m² g⁻¹ for JUC-588 and 2482 m² g⁻¹ for JUC-589) and promising thermal and chemical stabilities. Furthermore, the high selectivity of CO₂/N₂ and CO₂/CH₄, excellent H₂ uptakes, and efficient dye adsorption are observed. This research thus provides a general strategy for constructing stable 3D COF architectures with adjustable pores via improving the valency of rigid building blocks.

Two unusual cubic (8-connected) building units and their derived 3D imine-linked COFs based on bcu nets have been designed and synthesized, which demonstrates highly crystalline structures, excellent surface areas, and large pore sizes.     

磁性共价有机框架材料吸附甲基橙和茜素绿两种阴离子有机染料

以自制的磁性共价有机框架材料(COF)为吸附剂,采用静态吸附法研究了其对甲基橙(MO)和茜素绿(AG-25)的吸附行为。 结果表明,在25 ℃,pH值6~8的条件下,磁性COF对两种阴离子染料的的吸附量分别为997和1314 mg/g。 两种染料的吸附等温线符合Langmuir等温吸附模型,表明吸附过程为单层吸附;吸附动力学均符合准二级动力学模型,说明吸附过程以化学吸附为主。 磁性COF对水体中的阴离子染料体现出高吸附量和快速吸附的特点,具有潜在的价值。     

阳离子共价有机框架对水中非甾体药物的强化去除

以三醛基间苯三酚(TFP)和溴化乙锭(EB)为单体, 在溶剂热条件下合成了一种二维β-酮烯胺类阳离子型共价有机框架(COF)材料. 所得TFP-EB COF呈现出良好的结晶度、 高的比表面积和丰富的溴化乙锭单元, 故可将其应用于水中非甾体抗炎药(NSAIDs)的去除.阳离子TFP-EB COF对双氯芬酸钠(DCF-S)和对氨基水杨酸钠(PAS-S)两种非甾体抗炎药表现出高的吸附能力和快的吸附动力学, 其饱和吸附容量分别可达350.4和145.3 mg/g. 而采用TFP与4,4'-二氨基联苯(BND)在类似条件下合成的中性TFP-BND COF则表现出较差的吸附性能, 其对DCF-S和PAS-S的饱和吸附容量分别仅有59.7和13.6 mg/g. TFP-EB COF的吸附性能比TFP-BND COF更优异, 这主要归因于TFP-EB COF孔道中存在的大量阳离子EB单元与NSAIDs中的羧基间存在强烈的静电作用. 此外, 竞争离子干扰和循环再生实验表明阳离子型TFP-EB COF在NSAIDs污染物的去除方面具有良好的应用前景.     

Stable Thiophene-sulfur Covalent Organic Frameworks for Oxygen Reduction Reaction(ORR)

Exploring novel materials deriving from earth resources to substitute for platinum(Pt) electrocatalyst to promote oxygen reduction reaction(ORR) of fuel cell cathode is very important. Herein, we have exploited two crystallographic thiophene-sulfur covalent organic frameworks(COFs), termed JUC-607 and JUC-608, as electrocatalysts that exhibited good ORR performances. These thiophene-sulfur COFs exhibited high stability, and their functional groups acting as active centers in the ORR can be precisely determined. Notably, due to a larger aperture for mass transfer and electrons transport, JUC-608 displayed a growing electrochemical performance, leading to a better ORR activity. Thus, this study will provide a new strategy for designing heteroatom-based COF materials for high-performance electrochemical catalysis.     

Immobilization of Ionic Liquid on a Covalent Organic Framework for Effectively Catalyzing Cycloaddition of CO2 to Epoxides

Transforming CO₂ into value-added chemicals has been an important subject in recent years. The development of a novel heterogeneous catalyst for highly effective CO₂ conversion still remains a great challenge. As an emerging class of porous organic polymers, covalent organic frameworks (COFs) have exhibited superior potential as catalysts for various chemical reactions, due to their unique structure and properties. In this study, a layered two-dimensional (2D) COF, IM4F-Py-COF, was prepared through a three-component condensation reaction. Benzimidazole moiety, as an ionic liquid precursor, was integrated onto the skeleton of the COF using a benzimidazole-containing building unit. Ionization of the benzimidazole framework was then achieved through quaternization with 1-bromobutane to produce an ionic liquid-immobilized COF, i.e., BMIM4F-Py-COF. The resulting ionic COF shows excellent catalytic activity in promoting the chemical fixation of CO₂ via reaction with epoxides under solvent-free and co-catalyst-free conditions. High porosity, the one-dimensional (1D) open-channel structure of the COF and the high catalytic activity of ionic liquid may contribute to the excellent catalytic performance. Moreover, the COF catalyst could be reused at least five times without significant loss of its catalytic activity.     

Ag Nanoparticles Supported on a Resorcinol‐Phenylenediamine‐Based Covalent Organic Framework for Chemical Fixation of CO2

Covalent organic frameworks are a new class of crystalline organic polymers possessing a high surface area and ordered pores. Judicious selection of building blocks leads to strategic heteroatom inclusion into the COF structure. Owing to their high surface area, exceptional stability and molecular tunability, COFs are adopted for various potential applications. The heteroatoms lining in the pores of COF favor synergistic host–guest interaction to enhance a targeted property. In this report, we have synthesized a resorcinol‐phenylenediamine‐based COF which selectively adsorbs CO₂ into its micropores (12 Å). The heat of adsorption value (32 kJ mol^?1) obtained from the virial model at zero‐loading of CO₂ indicates its favorable interaction with the framework. Furthermore, we have anchored small‐sized Ag nanoparticles (≈4–5 nm) on the COF and used the composite for chemical fixation of CO₂ to alkylidene cyclic carbonates by reacting with propargyl alcohols under ambient conditions. Ag@COF catalyzes the reaction selectively with an excellent yield of 90 %. Recyclability of the catalyst has been demonstrated up to five consecutive cycles. The post‐catalysis characterizations reveal the integrity of the catalyst even after five reaction cycles. This study emphasizes the ability of COF for simultaneous adsorption and chemical fixation of CO₂ into corresponding cyclic carbonates.     

Postsynthetic Functionalization of Three‐Dimensional Covalent Organic Frameworks for Selective Extraction of Lanthanide Ions

Chemical functionalization of covalent organic frameworks (COFs) is critical for tuning their properties and broadening their potential applications. However, the introduction of functional groups, especially to three‐dimensional (3D) COFs, still remains largely unexplored. Reported here is a general strategy for generating a 3D carboxy‐functionalized COF through postsynthetic modification of a hydroxy‐functionalized COF, and for the first time exploration of the 3D carboxy‐functionalized COF in the selective extraction of lanthanide ions. The obtained COF shows high crystallinity, good chemical stability, and large specific surface area. Furthermore, the carboxy‐functionalized COF displays high metal loading capacities together with excellent adsorption selectivity for Nd³⁺ over Sr²⁺ and Fe³⁺ as confirmed by the Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. This study not only provides a strategy for versatile functionalization of 3D COFs, but also opens a way to their use in environmentally related applications.     

Tetrathiafulvalene-based covalent organic frameworks for ultrahigh iodine capture

To safeguard the development of nuclear energy, practical techniques for capture and storage of radioiodine are of critical importance but remain a significant challenge. Here we report the synergistic effect of physical and chemical adsorption of iodine in tetrathiafulvalene-based covalent organic frameworks (COFs), which can markedly improve both iodine adsorption capacity and adsorption kinetics due to their strong interaction. These functionalized architectures are designed to have high specific surface areas (up to 2359 m² g⁻¹) for efficient physisorption of iodine, and abundant tetrathiafulvalene functional groups for strong chemisorption of iodine. We demonstrate that these frameworks achieve excellent iodine adsorption capacity (up to 8.19 g g⁻¹), which is much higher than those of other materials reported so far, including silver-doped adsorbents, inorganic porous materials, metal–organic frameworks, porous organic frameworks, and other COFs. Furthermore, a combined theoretical and experimental study, including DFT calculations, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, reveals the strong chemical interaction between iodine and the frameworks of the materials. Our study thus opens an avenue to construct functional COFs for a critical environment-related application.

The synergistic effect of physical and chemical adsorption of iodine in tetrathiafulvalene-based covalent organic frameworks (COFs) has been explored. The iodine adsorption capacity of these materials is higher than other materials reported so far.     

基于醌基的共价有机框架用于电催化析氧反应

将蒽醌作为构筑单元设计合成了醌基功能化的新型2,6-二氨基蒽醌共价有机框架(DAAQ-COF). 粉末X射线衍射、 氮气吸附-脱附、 红外和热重等分析结果表明, DAAQ-COF具有高的结晶度和比表面积(577 m²/g). 此外, 醌基功能化的无金属DAAQ-COF显示出高的析氧反应(OER)活性(10 mA/cm²下, 过电位389 mV, Tafel斜率135 mV/dec). 这源于引入的醌基基团有效改变了COF框架的电子结构和化学特性, 加上COF材料本身的高结晶度和比表面积, 使得反应物能更有效地与活性位点接触, 从而促进OER进程. 这些结果表明合理地设计功能化的COF材料能够进一步推动此类材料在电催化领域的应用.     

卟啉-硫醚基共价有机框架材料用于氧还原反应电催化剂

氧还原反应（ORR）是能进行能量存储的核心电化学过程。由于它的动力学速率缓慢,因此亟需制备出高活性的电催化剂来促进这一反应的速率。二维共价有机框架材料（2D COFs）的π-π堆积结构可赋予骨架高导电率,并且一维有序的孔道有利于促进中间反应体传输。因此,其在可再生能源领域中具有良好的应用前景,并有望作为能量存储与转化的强大催化平台。本文通过向2D COFs中引入金属卟啉单元及硫醚单元成功制备了两个2D COFs （JUC-600和JUC-601）。通过多种表征手段证明,这两个2D COFs均具有AA堆积的sql拓扑结构。通过电化学测试表明,Co²⁺配位的JUC-601具有更正的ORR起始电势（0.825 V）和半波电势（0.7 V）、更高的活性表面积（7.8 mF/cm²）,更低的Tafel斜率（58 mV/dec）。这主要是由于JUC-601的高比表面积和高孔隙率使得中间产物能更易在COFs的表面和孔道中接触和传输。此外,Co²⁺-卟啉单元以及硫醚单元的存在使其骨架整体的电子结构发生了变化,更有利于电子转移。这一工作不仅开发了新的二维卟啉-硫醚基COFs材料,同时也拓展了2D COFs材料在电催化领域的应用。     

Positively charged covalent organic framework and its application in the dispersive solid-phase extraction of ultraviolet-filters from food packaging material migrants

Abstract

Covalent organic frameworks (COFs) show excellent property, such as high porosity and excellent structure stability and were well applied in fields such as catalysis and adsorption, but most of the COFs showed similar structure and thus similar adsorption performance. Modification of simple COFs to enhance its adsorption performance in separation technique is an important issue. In this study, quaternary ammonium groups with long hydrophobic chain were introduced into a simple COF (TpPa-1) for the first time. The positively charged COF (PC-TpPa-1) can form electrostatic interaction and hydrophobic effect with negatively charged analytes, and showed good adsorption performance for ultraviolet-filters (UV filters). Under the optimum conditions, i.e. adsorbent amount 20?mg, pH?=?7, 1.0?mL acetonitrile as eluent, the obtained recoveries for all UV filters were in the range of 86.4–96.7%.The developed method was successfully applied to the determination of UV filters from food packaging material migrants with the aid of HPLC as a detector.     

A heteropore covalent organic framework for adsorptive removal of Cd(Ⅱ) from aqueous solutions with high efficiency

A heteropore covalent organic framework(COF) integrating tetraphenylethene skeleton and catechol segment is designed and synthesized.It exhibits extremely high stability in water under different pH conditions,which makes it an excellent material for adsorptive removal of Cd(Ⅱ) from aqueous solutions with very fast adsorption kinetics,high uptake capacity,and good recyclability.     

CO2 Capture by Hydroxylated Azine-Based Covalent Organic Frameworks

Covalent organic frameworks (COFs) RIO-13, RIO-12, RIO-11, and RIO-11m were investigated towards their CO₂ capture properties by thermogravimetric analysis at 1 atm and 40 °C. These microporous COFs bear in common the azine backbone composed of hydroxy-benzene moieties but differ in the relative number of hydroxyl groups present in each material. Thus, their sorption capacities were studied as a function of their textural and chemical properties. Their maximum CO₂ uptake values showed a strong correlation with an increasing specific surface area, but that property alone could not fully explain the CO₂ uptake data. Hence, the specific CO₂ uptake, combined with DFT calculations, indicated that the relative number of hydroxyl groups in the COF backbone acts as an adsorption threshold, as the hydroxyl groups were indeed identified as relevant adsorption sites in all the studied COFs. Additionally, the best performing COF was thoroughly investigated, experimentally and theoretically, for its CO₂ capture properties in a variety of CO₂ concentrations and temperatures, and showed excellent isothermal recyclability up to 3 cycles.     

A Three-dimensional Covalent Organic Framework for CO2 Uptake and Dyes Adsorption

Environmental pollution is one of the most severe problems facing today, including water pollution and the greenhouse effect. Therefore, developing materials with high-efficiency dyes adsorption and CO₂ uptake is significant. Covalent organic frameworks(COFs), as a burgeoning class of crystalline porous polymers, present a promising application potential in areas related to pollution regulation due to their exciting surface properties. Herein, we report a 3D COF with a high specific surface area(BET about 2072 m²/g) by utilizing tetrahedral and rectangle building blocks connected through[4+4] imine condensation reactions to synthesize. The obtained COF not only can separate dyes from water effectively but also shows a remarkable CO₂ uptake capacity. This research thus provides a promising material to remove dyes and adsorb CO₂ in environmental remediation.