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Vipin Mishra Vivek K. Yadav Jayant K. Singh Thiruvancheril G. Gopakumar 《化学:亚洲杂志》2019,14(24):4645-4650
Imine COF (covalent organic framework) based on the Schiff base reaction between p‐phenylenediamine (PDA) and benzene‐1,3,5‐tricarboxaldehyde (TCA) was prepared on the HOPG‐air (air=humid N2) interface and characterized using different probe microscopies. The role of the molar ratio of TCA and PDA has been explored, and smooth domains of imine COF up to a few μm are formed for a high TCA ratio (>2) compared to PDA. It is also observed that the microscopic roughness of imine COF is strongly influenced by the presence of water (in the reaction chamber) during the Schiff base reaction. The electronic property of imine COF obtained by tunneling spectroscopy and dispersion corrected density functional theory (DFT) calculation are comparable and show semiconducting nature with a band gap of ≈1.8 eV. Further, we show that the frontier orbitals are delocalized entirely over the framework of imine COF. The calculated cohesive energy shows that the stability of imine COF is comparable to that of graphene. 相似文献
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Huijie He Xu Fang Dr. Dong Zhai Wei Zhou Yimeng Li Wenling Zhao Dr. Chengcheng Liu Dr. Zhen Li Prof. Weiqiao Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(58):14390-14395
Imines are important intermediates in drug synthesis. Photocatalytic aerobic oxidative coupling of amines has been considered as a clean and promising way to produce imines and has attracted great attention. Herein, we designed and synthesized a novel two-dimensional porphyrin-based covalent organic framework (Por-BC-COF) which adopts an AA stacking mode with excellent crystallinity, high Brunauer–Emmett–Teller surface areas (1200 m2 g−1), wide light absorption range (200–1300 nm) and good stability in a variety of organic solvents. Por-BC-COF can be used as a metal-free heterogeneous photocatalyst for the photocatalytic oxidation of amines to imines under visible light and red light with a high yield (97 %). This work presents a novel and efficient COF photocatalyst in the application of light-driven organic synthesis. 相似文献
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An Azine‐Linked Covalent Organic Framework: Synthesis,Characterization and Efficient Gas Storage
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Zhongping Li Yongfeng Zhi Xiao Feng Xuesong Ding Yongcun Zou Prof. Xiaoming Liu Prof. Ying Mu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(34):12079-12084
A azine‐linked covalent organic framework, COF‐JLU2, was designed and synthesized by condensation of hydrazine hydrate and 1,3,5‐triformylphloroglucinol under solvothermal conditions for the first time. The new covalent organic framework material combines permanent micropores, high crystallinity, good thermal and chemical stability, and abundant heteroatom activated sites in the skeleton. COF‐JLU2 possesses a moderate BET surface area of over 410 m2 g?1 with a pore volume of 0.56 cm3 g?1. Specifically, COF‐JLU2 displays remarkable carbon dioxide uptake (up to 217 mg g?1) and methane uptake (38 mg g?1) at 273 K and 1 bar, as well as high CO2/N2 (77) selectivity. Furthermore, we further highlight that it exhibits a higher hydrogen storage capacity (16 mg g?1) than those of reported COFs at 77 K and 1 bar. 相似文献
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Yanming Zhao Wenhao Dai Yunlei Peng Zheng Niu Qi Sun Chuan Shan Hui Yang Gaurav Verma Lukasz Wojtas Daqiang Yuan Zhenjie Zhang Haifeng Dong Xueji Zhang Bao Zhang Yaqing Feng Shengqian Ma 《Angewandte Chemie (International ed. in English)》2020,59(11):4354-4359
Herein, for the first time, we present the successful synthesis of a novel two‐dimensional corrole‐based covalent organic framework (COF) by reacting the unusual approximately T‐shaped 5,10,15‐tris(p‐aminophenyl)corrole H3TPAPC with terephthalaldehyde, which adopts desymmetrized hcb topology and consists of a staggered AB stacking structure with elliptical pores. The resultant corrole‐based COF, TPAPC‐COF , exhibits high crystallinity and excellent chemical stability. The combination of extended π‐conjugated backbone and interlayer noncovalent π–π interactions endows TPAPC‐COF with excellent absorption capability in the entire visible‐light and even near‐infrared regions. Moreover, this work suggests the promise of TPAPC‐COF as a new class of photoactive material for efficient singlet‐oxygen generation with potential photodynamic therapy application as demonstrated by in vitro anticancer studies. 相似文献
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Wei Zheng Junjun Hou Cuijing Liu Pengchao Liu Prof. Lianshan Li Prof. Li Chen Prof. Zhiyong Tang 《化学:亚洲杂志》2021,16(22):3624-3629
Covalent organic frameworks (COFs) are promising materials for membrane separation thanks to their adjustable topological structures and surface properties of nanopores. Herein, a melamine (Me)-doped COF membrane was fabricated by chemically doping the melamine monomer into TpPa COF, which is formed by the condensation reaction between the 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa) monomers via interfacial polymerization. The introduction of melamine monomer allows altering both the pore structure and pore surface of the TpPa COF membrane, leading to enhanced hydrogen purification performance. Specifically, the separation factor of H2/CO2 gas mixture by using the melamine doped TpPa COF (TpPaMe COF) membrane reaches 12.7, with a hydrogen permeance of 727 GPU, in sharp contrast to the relatively low separation factor and gas permeance of 7.5 and 618 GPU of the undoped TpPa membrane. Besides, the TpPaMe COF membrane shows good running stability, with H2/CO2 separation performance well surpasses the Robeson 2008 upper bound. 相似文献
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Ignacio Romero‐Muiz Andreas Mavrandonakis Pablo Albacete Alicia Vega Valrie Briois Flix Zamora Ana E. Platero‐Prats 《Angewandte Chemie (International ed. in English)》2020,59(31):13013-13020
Layered covalent organic frameworks (2D‐COFs), composed of reversible imine linkages and accessible pores, offer versatility for chemical modifications towards the development of catalytic materials. Nitrogen‐enriched COFs are good candidates for binding Pd species. Understanding the local structure of reacting Pd sites bonded to the COF pores is key to rationalize interactions between active sites and porous surfaces. By combining advanced synchrotron characterization methods with periodic computational DFT modeling, the precise atomic structure of catalytic Pd sites attached to local defects is resolved within an archetypical imine‐linked 2D‐COF. This material was synthesized using an in situ method as a gel, under which imine hydrolysis and metalation reactions are coupled. Local defects formed in situ within imine‐linked 2D‐COF materials are highly reactive towards Pd metalation, resulting in active materials for Suzuki–Miyaura cross‐coupling reactions. 相似文献
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Hai‐Long Qian Fan‐Lin Meng Cheng‐Xiong Yang Xiu‐Ping Yan 《Angewandte Chemie (International ed. in English)》2020,59(40):17607-17613
Design of stable adsorbents for selective gold recovery with large capacity and fast adsorption kinetics is of great challenge, but significant for the economy and the environment. Herein, we show the design and preparation of an irreversible amide‐linked covalent organic framework (COF) JNU‐1 via a building block exchange strategy for efficient recovery of gold. JNU‐1 was synthesized through the exchange of 4,4′‐biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)trianiline (Tz) and BA with terephthaloyl chloride. The irreversible amide linked JNU‐1 gave good stability, unprecedented fast kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery. X‐ray photoelectron spectroscopy along with thermodynamic study and quantum mechanics calculation reveals that the excellent performance of JNU‐1 for gold recovery results from the formation of hydrogen bonds C(N)?H???Cl and coordinate interaction of O and Au. The rational design of irreversible bonds as both inherent linkage and functional groups in COFs is a promising way to prepare stable COFs for diverse applications. 相似文献
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共价有机框架(covalent organic framework, COF)是一种由轻质元素(C、H、O和N)以共价键的形式连接组成的结晶多孔聚合物,由于其具有规则的孔道、可修饰的骨架以及良好的稳定性而被广泛应用于不同的领域.尤其是将含氮的功能基团连接到COF的骨架中,可以为其吸附特定的染料提供丰富的活性位点.基于此,本工作成功制备了一种酰胺功能化的二维共价有机框架材料(JUC-578),通过一系列的表征证明了该材料具有高的结晶度、均一规整的形貌以及开放的一维介孔孔道.更重要的是,发现JUC-578可以选择性地吸附阳离子染料,并且可以多次循环利用.这主要归因于骨架中的氮作为电子给体与缺电子的染料之间的静电作用以及其他弱相互作用(氢键、偶联作用等).与此同时,JUC-578高的结晶度和有序的孔道也是实现可逆吸附染料非常重要的因素. 相似文献
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Ji‐Long Shi Rufan Chen Huimin Hao Cheng Wang Xianjun Lang 《Angewandte Chemie (International ed. in English)》2020,59(23):9088-9093
2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon‐conjugated porphyrin‐based covalent organic framework (Por‐sp2c‐COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light‐emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π‐conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por‐sp2c‐COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por‐sp2c‐COF is pivotal for cooperative photocatalysis with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis. 相似文献
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Chao Sun Yuhao Zhu Pengpeng Shao Liwei Chen Xin Huang Shuang Zhao Dou Ma Xuechun Jing Prof. Dr. Bo Wang Prof. Dr. Xiao Feng 《Angewandte Chemie (International ed. in English)》2023,62(11):e202217103
Atmospheric water harvesting represents a promising technique to address water stress. Advanced adsorbents have been rationally designed to achieve high water uptake, yet their water sorption kinetics and regeneration temperature greatly limit water production efficiency. Herein, we demonstrated that 2D covalent organic frameworks (COFs), featuring hydrophobic skeleton, proper hydrophilic site density, and 1D open channels significantly lowered the water diffusion and desorption energy barrier. DHTA-Pa COF showed a high water uptake of 0.48 g/g at 30 % R.H. with a remarkable adsorption rate of 0.72 L/Kg/h (298 K) and a desorption rate of 2.58 L/Kg/h (333 K). Moreover, more than 90 % adsorbed water could be released within 20 min at 313 K. This kinetic performance surpassed the reported porous materials and boosted the efficiency for multiple water extraction cycles. It may shed light on the material design strategy to achieve high daily water production with low-energy input. 相似文献
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Surface‐Confined Single‐Layer Covalent Organic Framework on Single‐Layer Graphene Grown on Copper Foil
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Lirong Xu Xin Zhou Prof. Wei Quan Tian Teng Gao Yan Feng Zhang Prof. Shengbin Lei Prof. Zhong Fan Liu 《Angewandte Chemie (International ed. in English)》2014,53(36):9564-9568
The integration of 2D covalent organic frameworks (COFs) with atomic thickness with graphene will lead to intriguing two‐dimensional materials. A surface‐confined covalently bonded Schiff base network was prepared on single‐layer graphene grown on copper foil and the dynamic reaction process was investigated with scanning tunneling microscopy. DFT simulations provide an understanding of the electronic structures and the interactions between the surface COF and graphene. Strong coupling between the surface COF and graphene was confirmed by the dispersive bands of the surface COF after interaction with graphene, and also by the experimental observation of tunneling condition dependent contrast of the surface COF. 相似文献
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Johannes Maschita Tanmay Banerjee Gkcen Savasci Frederik Haase Christian Ochsenfeld Bettina V. Lotsch 《Angewandte Chemie (International ed. in English)》2020,59(36):15750-15758
Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF. 相似文献
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Jingru Zhen Sanyuan Ding Wei Wang Junmin Liu Junliang Sun Zhitang Huang Qiyu Zheng 《中国化学》2016,34(8):783-787
Two 2D wavy hexagonal hexahydroxyl cyclotricatechylene (CTC) based COFs, CTC‐COF‐2 and CTC‐COF‐3 were synthesized through solvothermal reaction. The bowl‐shaped conformation caused CTC skeletons packed in a columnar manner with the same oriented units, thus forming an undulated structure. The gas adsorption properties of CTC‐COFs were investigated, which show the potential application abilities in hydrogen storage of CTC‐COFs. The introduction of pyrene into CTC‐COF‐3 makes it a potential semiconducting π‐conjugated material. 相似文献
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Yang Wang Bei Guo Tong Yang Zhi-Cong Zhang Dr. Lin Liang Prof. San-Yuan Ding Prof. Wei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(46):e202200961
The weak interaction of covalent organic framework (COF) nanoparticles makes the preparation of self-standing COF films difficult. Herein, a modulated strategy for the facile synthesis of self-standing COF films with good crystallinity and tunable thickness is reported. As compared with the non-modulated approach, the modulated strategy changes the COF morphology from nanoparticles to nanofibers, enabling the facile preparation of self-standing COF films with improved mechanical properties. The Young's modulus of the self-standing COF film obtained via the modulated strategy could increase by 26 times. Moreover, self-standing LZU-8 film can be used as a membrane for efficient removal of 99 % mercury ions from aqueous solution. Our results open up a new approach to prepare self-standing COF thin films for practical applications. 相似文献
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Direct On‐Surface Patterning of a Crystalline Laminar Covalent Organic Framework Synthesized at Room Temperature
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Alejandro de la Peña Ruigómez David Rodríguez‐San‐Miguel Dr. Kyriakos C. Stylianou Dr. Massimiliano Cavallini Dr. Denis Gentili Dr. Fabiola Liscio Prof. Silvia Milita Dr. Otello Maria Roscioni Dr. Maria Luisa Ruiz‐González Carlos Carbonell Prof. Daniel Maspoch Dr. Rubén Mas‐Ballesté Dr. José Luis Segura Dr. Félix Zamora 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(30):10666-10670
We report herein an efficient, fast, and simple synthesis of an imine‐based covalent organic framework (COF) at room temperature (hereafter, RT‐COF‐1 ). RT‐COF‐1 shows a layered hexagonal structure exhibiting channels, is robust, and is porous to N2 and CO2. The room‐temperature synthesis has enabled us to fabricate and position low‐cost micro‐ and submicropatterns of RT‐COF‐1 on several surfaces, including solid SiO2 substrates and flexible acetate paper, by using lithographically controlled wetting and conventional ink‐jet printing. 相似文献
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Supramolecular Reassembly of Self‐Exfoliated Ionic Covalent Organic Nanosheets for Label‐Free Detection of Double‐Stranded DNA
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Arindam Mal Dr. Rakesh K. Mishra Dr. Vakayil K. Praveen M. Abdul Khayum Dr. Rahul Banerjee Prof. Dr. Ayyappanpillai Ajayaghosh 《Angewandte Chemie (International ed. in English)》2018,57(28):8443-8447
Ionic covalent organic nanosheets (iCONs), a member of the two‐dimensional (2D) nanomaterials family, offer a unique functional platform for a wide range of applications. Herein, we explore the potential of an ethidium bromide (EB)‐based covalent organic framework ( EB‐TFP ) that self‐exfoliates in water resulting in 2D ionic covalent organic nanosheets ( EB‐TFP‐iCONs ) for the selective detection of double‐stranded DNA (dsDNA). In an aqueous medium, the self‐exfoliated EB‐TFP‐iCONs reassemble in the presence of dsDNA resulting in hybrid EB‐TFP‐iCONs‐DNA crystalline nanosheets with enhanced fluorescence at 600 nm. Detailed steady‐state and time‐resolved emission studies revealed that the reassembly phenomenon was highly selective for dsDNA when compared to single‐stranded DNA (ssDNA), which allowed us to use the EB‐TFP‐iCONs as a 2D fluorescent platform for the label‐free detection of complementary DNA strands. 相似文献
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Huimin Ding Yonghai Li Hui Hu Dr. Yimeng Sun Jianguo Wang Caixing Wang Prof. Dr. Cheng Wang Dr. Guanxin Zhang Prof. Dr. Baoshan Wang Prof. Dr. Wei Xu Prof. Dr. Deqing Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14614-14618
Two‐dimensional covalent organic frameworks (2D COFs) provide a unique platform for the molecular design of electronic and optoelectronic materials. Here, the synthesis and characterization of an electroactive COF containing the well‐known tetrathiafulvalene (TTF) unit is reported. The TTF‐COF crystallizes into 2D sheets with an eclipsed AA stacking motif, and shows high thermal stability and permanent porosity. The presence of TTF units endows the TTF‐COF with electron‐donating ability, which is characterized by cyclic voltammetry. In addition, the open frameworks of TTF‐COF are amenable to doping with electron acceptors (e.g., iodine), and the conductivity of TTF‐COF bulk samples can be improved by doping. Our results open up a reliable route for the preparation of well‐ordered conjugated TTF polymers, which hold great potential for applications in fields from molecular electronics to energy storage. 相似文献
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ZHANG Jianhui LIU Jianchuan LIU Yaozu WANG Yujie FANG Qianrong QIU Shilun 《高等学校化学研究》2022,38(2):456-460
Radioactive iodine is a notorious pollutant in gas radioactive nuclear waste due to its radiation hazard, volatility, chemical toxicity, and high mobility. Therefore, developing a material with high efficiency-specific iodine capture is significant. Covalent organic framework(COF) has attracted significant attention as a new crystalline porous organic material. Due to its large specific surface and high chemical stability, it is an excellent alternative to adsorbents. Herein, we report a chemically stable two-dimensional COF(termed JUC-609) with specific adsorption of iodine. Adsorption experiments show that JUC-609 has an excellent iodine adsorption capacity as high as 5.9 g/g under 353 K and normal pressure condition, and iodine adsorption after multiple cycles is still maintained. Our study thus promotes the potential application of COFs in the field of environment-related applications. 相似文献