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Covalent Organic Frameworks

Lei Fang, Xinrui Cao, Zexing Cao
Covalent organic frameworks (COFs) generally have high stability, large charge capacity and wide ion diffusion paths, and they may serve as the potential electrode materials for the lithium ion batteries. Here we explored the structural, electronic, and lithium-storage properties of the newly synthesized NUS-2 COF material by the first-principles calculations. The present results indicate that the micropore environment and the presence of the carbonyl oxygens in the NUS-2 COF can prevent from the formation lithium dimer and the aggregation of lithium bulk, which can improve lithiation efficiency...
February 19, 2019: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Lingling Wang, Cheng Zeng, Hong Xu, Panchao Yin, Dongcheng Chen, Jian Deng, Mu Li, Nan Zheng, Cheng Gu, Yuguang Ma
Covalent organic frameworks (COFs) have emerged as a tailor-made platform for designing next-generation two-dimensional materials. However, COFs are produced as insoluble and unprocessable solids, which precludes the preparation of thin films for optoelectronic applications. Here, we report designed synthesis of a highly soluble yet crystalline COF material through the regulation of its inter-layer interactions. The resulting COF is remarkably soluble in a variety of organic solvents and forms stable true solutions with retention of its layered structure...
January 28, 2019: Chemical Science
Jian-Xin Ma, Jian Li, Yi-Fan Chen, Rui Ning, Yu-Fei Ao, Jun-Min Liu, Junliang Sun, De-Xian Wang, Qi-Qiang Wang
The first two cage based crystalline covalent organic frameworks, cage-COF-1 and cage-COF-2, were constructed from a prism-like three-aldehyde-containing molecular cage. The cage contains two horizontal phloroglucinol and three vertical triazine moieties forming three identical V-shaped cavities. By reacting with p-phenylenediamine and 4,4'-biphenyldiamine, the two cage-COFs were formed with a hexagonal skeleton and possess a unique structure. Due to the pillared cage nodes, the linkers are hanging with their π-surfaces but not C-H sites exposed to the pore, and enjoy certain rotational dynamics as suggested by 13 C CP/MAS NMR...
February 18, 2019: Journal of the American Chemical Society
Liang Zhao, Muhammad R Azhar, Xiaojie Li, Xiaoguang Duan, Hongqi Sun, Shaobin Wang, Xiangchen Fang
Cerium is an important rare earth element (REE), which can be used for many high-tech applications. From the industrial and environmental viewpoints, it is imperative to recover Ce3+ ions from aqueous solution. Herein, HKUST-1 metal-organic framework (MOF) was applied for adsorption and recovery of Ce3+ from aqueous solution. HKUST-1 showed a high adsorption efficiency and remarkable capacity of 353 mg/g at pH = 6. The isotherm, kinetics, effect of pH value and adsorption mechanism of the Ce3+ adsorption process were also studied...
January 31, 2019: Journal of Colloid and Interface Science
Huilin Liu, Ying Zhang, Dianwei Zhang, Fuping Zheng, Mingquan Huang, Jinyuan Sun, Xiaotao Sun, Hehe Li, Jing Wang, Baoguo Sun
An efficient and rapid fluorescent nanoprobe is described for the determination of the aroma compound 4-ethylguaiacol (4-EG). A molecularly imprinted polymer was doped with a covalent organic framework (COF) grafted onto carbon nanodots that was prepared by one-pot reverse microemulsion polymerization. Amino groups at the surface of carbon nanodots coordinate to the COFs to produce a strong bond and this warrants thermal and chemical stability of the probe. Remaining free amino groups interact with the phenolic hydroxyl groups of 4-EG through acid-base pairing interactions...
February 15, 2019: Mikrochimica Acta
Fernando Maya, Brett Paull
This review summarizes recent development made in the incorporation of functional materials into organic polymer monoliths, together with new monolithic forms and formats, which enhance their application as supports and stationary phase materials for sample preparation and chromatographic separations. While polymer monoliths are well known supports for the separation of large molecules, recent development have been made to improve their features for the separation of small molecules. The selectivity and performance of organic polymer monoliths has been improved by the incorporation of different materials, such as metal-organic frameworks, covalent organic frameworks, or other types of nanostructured materials (carbon nanohorns, nanodiamonds, polyoxometalates, layered double hydroxides, or attapulgite)...
February 15, 2019: Journal of Separation Science
Yingjie Zhao, Hui Liu, Chenyu Wu, Zhaohui Zhang, Qingyan Pan, Fan Hu, Ruiming Wang, Piwu Li, Xiaowen Huang, Zhibo Li
The synthesis of fully sp2-carbon conjugated covalent organic framework (COF) is extremely challenging given the difficulty of "irreversible" carbon-carbon double bond (-C=C-) formation. Here, we report the successful preparation of a 2D COF (TP-COF) based on triazine as central planar units bridged by sp2-carbon linkers through the -C=C- condensation reaction. High-resolution-transmission electron microscopy (HRTEM) clearly confirmed the tessellated hexagonal pore structure with a pore center-to-center distance of 2 nm...
February 13, 2019: Angewandte Chemie
Yanli Zhao, Zhuang Miao, Guiyan Liu, Yumeng Cui, Zhengyu Liu, Jinheng Li, Fangwai Han, Yu Liu, Xiaoxiao Sun, Xuefang Gong, Yufeng Zhai, Yongfei Zeng
The field of covalent organic frameworks (COFs) has been significantly developed in the past decade on account of their important characteristics and vast application potential. On the other hand, the discovery of novel synthetic methodology is still a challenging task to further promote the preparation of COFs. Herein, an interesting protocol for the conversion of amorphous nonporous covalent organic polymers (COPs) to COFs was established, affording four COFs with high crystallinity and porosity. Specifically, imine-linked amorphous COP-1 was successfully converted to COF-1~4 by replacing one type of linker with other organic building blocks...
February 13, 2019: Angewandte Chemie
Bin Ni, Yuquan Li, Taiqiang Chen, Ting Lu, Likun Pan
Covalent organic frameworks (COFs) with devisable nanostructures have exhibited extensive application prospects in energy storage and conversion. In this work, spherical COFs were successfully utilized as an ideal precursor for N, B co-doped carbon spheres (NBCs) that display hierarchical spherical architectures with rich pores. When applied as lithium ion batteries (LIBs) anode, NBCs exhibit high reversible specific capacity and outstanding long-life cycling stability (205.5 mAh g-1 at 5.0 A g-1 and 171...
February 4, 2019: Journal of Colloid and Interface Science
Michael C Daugherty, Edon Vitaku, Rebecca L Li, Austin M Evans, Anton D Chavez, William R Dichtel
β-Ketoenamine-linked covalent organic frameworks (COFs) offer excellent structural versatility and outstanding aqueous stability, but their stability complicates obtaining samples with high crystallinity and surface areas. In contrast, imine-linked COFs are often isolated with superior materials quality. Here we synthesize several β-ketoenamine-linked COFs, including two unreported structures, with unmatched crystallinity and high surface areas by preparing the corresponding imine-linked COF and exchanging its triformylbenzene monomers with triformylphloroglucinol...
February 12, 2019: Chemical Communications: Chem Comm
Debabrata Samanta, Syamantak Roy, Ranjan Sasmal, Nilanjana Das Saha, Pradeep K R, Ranjani Viswanatha, Sarit S Agasti, Tapas Kumar Maji
A solvent responsive dynamic nanoscale metal-organic framework (NMOF) [Zn(1a)(H2O)2] has been devised based on the self-assembly of ZnII and asymmetric bola-amphiphilic oligo-(p-phenyleneethynylene) (OPE) dicarboxylate linker 1a having dodecyl and triethyleneglycolmonomethylether (TEG, polar) side chains. In THF solvent, NMOF showed nanovesicular morphology (NMOF-1) with surface decorated dodecyl chains. In water and methanol, NMOF exhibited inverse-nanovesicle (NMOF-2) and nanoscroll (NMOF-3) morphology, respectively, with surface projected TEG chains...
February 11, 2019: Angewandte Chemie
Ahmed F M El-Mahdy, Christine Young, Jeonghun Kim, Jungmok You, Yusuke Yamauchi, Shiao-Wei Kuo
Covalent organic frameworks (COFs) are a family of crystalline porous networks having applications in various fields, including gas and energy storage. Despite respectable progress in the synthesis of such crystalline materials, examples of the use of template-free methods to construct COFs having hollow nano- and microstructures are rare. Furthermore, all reported methods for synthesizing these hollow structural COFs have involved [4+2] and [3+2] condensations. Herein, we report the synthesis of hollow microspherical and microtubular carbazole-based COFs through template-free, one-pot, [3+3] condensations of the novel triamine 9-(4-aminophenyl)-carbazole-3,6-diamine (Car-3NH2) and triformyl linkers with various degrees of planarity...
February 8, 2019: ACS Applied Materials & Interfaces
Sainan Liu, Chunling Hu, Ying Liu, Xueyan Zhao, Maolin Pang, Jun Lin
Covalent organic frameworks (COFs) have attracted great attention across diverse research fields, however, only a few reports about the biomedical application of COFs could be found in the open literature. Attributed to the highly porous and tunable structure, as well as good thermal stability, COF shows great potential as a drug carrier for chemotherapy. In this work, doxorubicin (DOX) was successfully in situ loaded into a COF by a one-pot method for the first time. The resultant DOX@COF platform exhibited high drug loading capacity (32...
February 8, 2019: Chemistry: a European Journal
Yan Yang, Ka Un Lao, Robert A DiStasio
Despite the importance of porous two-dimensional (2D) molecules and materials in advanced technological applications, the question of how the void space in these systems affects the van der Waals (vdW) scaling landscape has been largely unanswered. Analytical and numerical models presented herein demonstrate that the mere presence of a pore leads to markedly different vdW scaling across nonasymptotic distances, with certain relative pore sizes yielding effective power laws ranging from simple monotonic decay to the formation of minima, extended plateaus, and even maxima...
January 18, 2019: Physical Review Letters
Shichen Yan, Xinyu Guan, Hui Li, Daohao Li, Ming Xue, Yushan Yan, Valentin Valtchev, Shilun Qiu, Qianrong Fang
The development of three-dimensional (3D) functionalized covalent organic frameworks (COFs) is of critical importance for expanding their potential applications. However, the introduction of functional groups in 3D COFs remains largely unexplored. Herein we report the first example of 3D Salphen-based COFs (3D-Salphen-COFs) and their metal-containing counterparts (3D-M-Salphen-COFs). These Salphen-based COFs exhibit high crystallinity and specific surface area in addition to excellent chemical stability. Furthermore, the Cu(II)-Salphen COF displays high activity in the removal of superoxide radicals...
February 4, 2019: Journal of the American Chemical Society
Xiumin Yang, Junmin Wang, Wenjin Wang, Shuaihua Zhang, Chun Wang, Junhong Zhou, Zhi Wang
A new covalent organic framework (COF) was synthesized by the amide coupling between 1,3,5-tris(4-aminophenyl)benzene and trimesoyl chloride at room temperature. The COF was applied as a steel fiber coating for the solid phase microextraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The effect of extraction time, salt concentration, and extraction temperature on the efficiency of SPME was optimized by a Box-Behnken design. The PAHs were quantified by gas chromatography with mass spectrometric detection...
February 1, 2019: Mikrochimica Acta
Nina Heidary, Tomos G A A Harris, Khoa H Ly, Nikolay Kornienko
Mimicking photosynthesis in generating chemical fuels from sunlight is a promising strategy to alleviate society's demand for fossil fuels. However, this approach involves a number of challenges that must be overcome before this concept can emerge as a viable solution to society's energy demand. Particularly in artificial photosynthesis, the catalytic chemistry that converts energy in the form of electricity into carbon-based fuels and chemicals has yet to be developed. Here, we describe the foundational work and future prospects of an emerging and promising class of materials: metal- and covalent-organic frameworks (MOFs and COFs)...
January 31, 2019: Physiologia Plantarum
Yang Wu, Dongwan Yan, Zhongyue Zhang, Michio M Matsushita, Kunio Awaga
To enhance the electron transfer within the covalent organic frameworks (COFs), a nanocomposite of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) and redox-active AQ-COF was obtained by performing a facile in situ solid-state polymerization inside the nanochannels of COFs. The PEDOT chains functioned like electron highways within the nanochannels, resulting in a PEDOT@AQ-COF nano-composite with an excellent electrical conductivity of 1.1 S cm-1 and a remarkably improved performance in faradaic energy storage...
January 31, 2019: ACS Applied Materials & Interfaces
Yanpei Song, Qi Sun, Briana Aguila, Shengqian Ma
Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The range of properties characterized in COFs has rapidly expanded to include those of interest for numerous applications ranging from energy to environment. Here, a background overview is provided, consisting of a brief introduction of porous materials and the design feature of COFs...
January 23, 2019: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Alejandro Cabrera-García, Elisa Checa-Chavarria, Eva Rivero-Buceta, Victoria Moreno, Eduardo Fernández, Pablo Botella
MIL-100(Fe) and MIL-101(Fe) metal-organic frameworks (MOFs) are excellent vehicles for drug delivery systems (DDSs) due to their high biocompatibility and stability in physiological fluids, as well as their pore diameter in the mesoporous range. Although they are appropriate for the internal diffusion of 20-(S)-camptothecin (CPT), a strongly cytotoxic molecule with excellent antitumor activity, no stable delivery system has been proposed so far for this drug based in MOFs. We here present novel DDSs based in amine functionalized MIL-100(Fe) and MIL-101(Fe) nanoMOFs with covalently bonded CPT...
January 17, 2019: Journal of Colloid and Interface Science
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