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Heterogeneous Catalytic Application of COFs
Published in Atsushi Nagai, Covalent Organic Frameworks, 2019
Covalent organic frameworks (COFs) are defined as highly porous and crystalline polymers, constructed and connected via covalent bonds, extending along two or three dimensions. As compared with other porous materials, such as zeolite and active carbon, the versatile and alternative constituent elements, chemical bonding types, and characteristics of the ordered skeleton and pores of COFs enable the creation of more COFs for diverse applications, including gas separation and storage, optoelectronics, proton conduction, and energy storage and, in particular, “catalysis.” The representative candidates of next-generation catalysis materials due to their large surface areas and accessible and size-tunable open nanopores, COFs are suitable for incorporating external useful active ingredients, such as ligands, complexes, and metal nanoparticles, and for substrate diffusion. This chapter will introduce and discuss examples of COFs for application in heterogeneous catalysts.
Emerging Applications of Covalent Organic Frameworks and Their Architectural Aspects for Improved Oxygen Evolution Reactions
Published in Tuan Anh Nguyen, Ram K. Gupta, Covalent Organic Frameworks, 2023
Karan Chaudhary, Dhanraj T. Masram
Covalent organic frameworks (COFs) are organic polymers that belong to a class of porous materials that are crystalline in nature having highly ordered structures and permanent porosity. In comparison to other polymers, COFs have several advantages like being synthetically controllable, structurally predesignable, and functionally manageable [4]. COFs are synthesized using organic units as building blocks that are linked to each other through strong covalent interactions [5]. Yaghi and co-workers in 2005 reported the first example of COF materials as COF-1 and COF-5 [6]. COFs can be synthesized as two-dimensional or three-dimensional frameworks with the presence of several heteroatoms in the structure by judicious selection of organic building blocks [7, 8]. At present, based on present research these organic porous polymer materials have been categorized as polymers of intrinsic micro-porosity (PIMs) [9], covalent organic frameworks [10], covalent triazine framework (CTF) [11], and conjugated micro-porous, and meso-porous polymers (CMPs) [12]. Several methods have been utilized to synthesize these COF materials which include ionothermal [11], mechanochemical [13], solvothermal [6], microwave [14], sonochemical [15], light-promoted [16], interfacial polymerization [17], and vapor-assisted conversion [18]. The merits associated with COFs are pre-designable, low density, porous structure, large accessible surface area, structural regularity, functionable and tunable, and excellent mechanical strength [19, 20]. Since the first report on COFs, a lot of efforts have been done in the development of these porous materials and as result, large numbers of research reports are available now. And this development of COFs is due to its associated merits. Based on these features, COFs have also been applied in various applications including energy storage [21], gas sensor [22, 23], catalysis [24, 25], drug delivery [26], electrocatalysis [27], and many others [4].
Tailoring electrospun nanofibrous materials for oil/water emulsion separation
Published in The Journal of The Textile Institute, 2022
Jichao Zhang, Lifang Liu, Yang Si, Shichao Zhang, Jianyong Yu
The above-mentioned textures on nanofibers induced by 0 D and 1 D nanoparticles are similar to the nanoprotrusions on lotus leaves. Covalent organic frameworks (COFs) are a class of crystalline porous materials built from organic linkers (Zhu et al., 2021). Recently, COFs have also attracted considerable attention in the development of separation membranes and demonstrate unique property (Wang et al., 2020). For instance, Zhang et al. incorporated COFs into PAN matrix through blend electrospinning (Zhang, Han et al., 2019). The synergistic effect of strong interaction between polymer matrix and COFs, and the mismatched size between COF nanoparticles and PAN nanofibers induced PAN macromolecules to present ellipsoid, resulting in a unique spindle-knotted structure. By the combination of spindle shape on fiber and superhydrophilic property of hydrolyzed PAN, the generated nonequilibrium Laplace pressure could drive the directional transport of oil droplets on spindle-knotted fibers underwater, thus aggregating oil droplets during separation. Consequently, the PAN/COF nanofibrous membrane displayed good recyclability.
Metalloporphyrin-based porous polymers prepared via click chemistry for size-selective adsorption of protein
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Dailian Zhu, Cunqi Qin, Shanshi Ao, Qiuping Su, Xiying Sun, Tengfei Jiang, Kemei Pei, Huagang Ni, Peng Ye
Covalent organic frameworks (COFs) as one kind of more robust crystalline porous material, the formation of 2D and 3D networks strongly depending on the link of rigid organic building blocks through strong covalent bonds [43]. Zinc porphyrin has a huge conjugated system with a rigid planar structure that would benefit the space effect of molecular recognition, such as p–p interaction and aromatic ring stacking interaction, but the crystal structure of the resultant PPS-Zn is not perfect due to inadequate rigidity of the building blocks with flexible methylene group in molecules. The crystalline state and morphologies of PPs-Zn, their XRD pattern and SEM images are shown in Figure S1 and S2 (Supporting Information). These materials exhibited an amorphous nature, and irregular spherical tiny particles are shown on the surface. According to the textural properties of these two kinds Zn-Ph networks, we prepared the various PPs-Zn networks with different pore size structure by varying the reaction condition of CuAAC. Then the adsorption behaviors of protein with different size were further investigated.