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Covalent organic frameworks (COFs) made of light atoms such as H, C, N, and O with a significant void-to-framework ratio are excellent low-density supports for nanoparticles (nPs). Their framework can be precoded with heteroatoms to ensure binding with metallic nanoclusters. With these advantages, if controlled amounts of magnetic nPs are anchored to them, they can yield low-density organic–inorganic nanomagnets. Their organic nature facilitates fusion with bulk materials such as paper/textile to enable bulk composites with well-dispersed low-density magnets, which have potential for defense and next-generation aviation applications. Herein, we have grown small Fe/Fe3O4 nPs (5–18 wt %) inside a COF. Interestingly, 300 mg of this organic–inorganic framework material (containing 50 mg of nPs) can lift a vial of ∼15,000 mg (300 times heavier). Also, the hydrophobic COF wraps around the Fe/Fe3O4 nanocluster retaining its room-temperature magnetic character even after 1 year, while the naked nPs lose it within a few days because of air oxidation. Bulk composites with paper and polymers have been made using this low-density Fe–COF to demonstrate their processability.

Water pollution has attracted worldwide significant attention ever since the finding of its harmful effects on the whole ecosystem, including human health. Although several materials are known for selective removal of specific contaminants, designing a single material that can adsorb a variety of water contaminants is still a very challenging task due to a lack of proper design strategies. Herein, we have rationally designed a new class of anion exchangeable hybrid material where the nanosized cationic metal–organic polyhedra (MOP) are embedded inside a porous covalent organic framework (COF) with specific binding sites for toxic oxoanions. The resulting hybrid material exhibits very fast and selective sequestration of high as well as trace amount of a wide range of toxic oxoanions (HAsO42–, SeO42–, CrO42–, ReO4–, and MnO4–) from the mixture of excessive (∼1000-fold) other interfering anions to well below the permissible drinking water limit. Moreover, the hybrid cationic nanotrap material can reduce the As(V) level from a highly contaminated groundwater sample to below the WHO permitted level.

A smart hybrid material composed of a metal−organic polyhedra (MOP) and covalent organic framework (COF) effectively and selectively captures toxic oxoanions from water.

共价有机骨架（COF）是一类具有永久孔隙度和高度有序结构的结晶多孔有机聚合物。与其他聚合物不同，COF的显着特征是它们在结构上是可预先设计的，可综合控制的和在功能上可控制的。原则上，拓扑设计图为扩展的多孔多边形的结构平铺提供几何指导，缩聚反应提供了构建预先设计的一级和高级结构的合成方法。过去十年中在这两个方面的化学进展无疑为COF领域奠定了基础。由于有机单元的可用性以及拓扑结构和链接的多样性，COF已成为有机材料的新领域，为复杂的结构设计和量身定制的功能开发提供了强大的分子平台。在这里，我们针对COF领域进行全面审查，对COF领域的化学性质进行历史性概述，调查拓扑设计和合成反应方面的进展，说明结构特征和多样性，通过以下方式仔细检查各种功能的发展和潜力阐明基于与光子，电子，空穴，自旋，离子和分子的相互作用的结构与功能的相关性，讨论需要解决的关键基本和挑战性问题，并从化学，物理和材料的角度预测未来的方向。

减少电化学二氧化碳的排放是将二氧化碳转化为有价值的燃料和化学品的可持续方法。在这里，我们通过在氨基官能化的碳纳米管上通过模板分离的共价有机骨架（COF）与分离的钴卟啉单元进行定向聚合，制备了一系列复合纳米材料，以实现有效的电催化CO2还原反应（CO2RR）。与纯COF相比，包裹在导电支架上的超薄COF纳米层的混合形式可在宽泛的电势范围内扩大电流密度和稳定的法拉第效率，从而实现CO2-CO转化。具体地，可以通过用不同官能团修饰网状结构来精细地优化系统的催化性能。我们的工作为制备高活性和选择性的CO2RR电催化剂提供了新的策略。

Since 1995 when the first of metal−organic frameworks was crystallized with the strong bond approach, where metal ions are joined by charged organic linkers exemplified by carboxylates, followed by proof of their porosity in 1998 and ultrahigh porosity in 1999, a revolution in the development of their chemistry has ensued. This is being reinforced by the discovery of two- and three-dimensional covalent organic frameworks in 2005 and 2007. Currently, the chemistry of such porous, crystalline frameworks is collectively referred to as reticular chemistry, which is being practiced in over 100 countries. The involvement of researchers from various backgrounds and fields, and the vast scope of this chemistry and its societal applications, necessitate articulating the “Standard Practices of Reticular Chemistry”.

酯键连接的，结晶的，多孔的共价有机骨架（COF）已经合成并在结构上进行了表征。二位2-吡啶基芳族羧酸盐与三或四位酚之间的酯交换反应得到相应的酯连接的COF。它们以kgm（COF-119）和hcb（COF-120、121、122）拓扑的2D结构结晶，表面积高达2092 m2 / g。值得注意的是，结晶的COF-122包含跨越10个亚苯基单元的边缘，这一方面只有在金属有机框架中才能实现。这项工作扩大了网状化学的范围，首次包括了与普通聚酯有关的结晶酯连接的COF。

Anionic covalent organic framework is an emerging class of functional materials in which included ionic species of the opposite charges play an important role in the ion conduction and selective gas adsorption. Herein, we reported a facile method to construct a series of germanate-based anionic COFs (Ge-COFs) by reticulating dianionic hexa-coordinated GeO6 nodes with anthracene building blocks adopting a hcb topology in an extended 2D framework. A systematic change of pore properties in Ge-COFs was observed through the incorporation of three different alkali metal cations: Li+, Na+, and K+. The intrinsically negatively charged backbone provides a host matrix with a homogeneous distribution of counter cations and poses variable and exciting features for gas adsorption and ionic conduction. Among the series, K+-based Ge-COF-K with a surface area of 1252 m2/g and pore volume of 0.84 cm3/g shows a maximum CO2 uptake of 126 cm3/g (247.4 mg/g) at 273 K and 1 bar, an IAST selectivity of 140 over N2. Ge-COF-K also exhibits a high SO2 kinetic breakthrough capacity of 154 mg/g at low ppm of SO2 concentration under ambient conditions among recently reported porous materials. Moreover, reasonably high lithium, sodium, and potassium ionic conductivities were observed with the values of 1.2 × 10–4, 3.4 × 10–5, and 2.2 × 10–5 S/cm for propylene carbonate infiltrated Ge-COF-Li, Ge-COF-Na, and Ge-COF-K at 100 °C, respectively.

受冰的超润滑表面（SLS）的启发，该表面由一层超薄且连续的表面结合水组成，我们通过静电纺丝在聚己内酯（PCL）/聚（2-甲基丙烯酰氧基乙基磷酰胆碱）（PMPC）复合纳米纤维膜上构建了SLS。在受控相对湿度（RH）下。纳米纤维上的两性离子PMPC提供了结合水的表面层，因此生成了水合润滑表面。在20％RH下制备的电纺PCL / PMPC纳米纤维在PMPC与PCL的重量比为0.1时达到约0.12的最小摩擦系数（COF）。在较高的相对湿度下，在复合纳米纤维上形成了超低COF小于0.05的SLS。工程纳米纤维膜上SLS水化层的高稳定性有效地抑制了成纤维细胞的粘附，并在体内肌腱修复过程中显着降低了组织的粘附。这项工作证明了这种受冰启发的SLS方法在预防组织粘连中的巨大潜力。

Large singlet exciton diffusion lengths are a hallmark of high performance in organic-based devices such as photovoltaics, chemical sensors, and photodetectors. In this study, exciton dynamics of a two-dimensional covalent organic framework, 2D COF-5, is investigated using ultrafast spectroscopic techniques. After photoexcitation, the COF-5 exciton decays via three pathways: (1) excimer formation (4 ± 2 ps), (2) excimer relaxation (160 ± 40 ps), and (3) excimer decay (>3 ns). Excitation fluence-dependent transient absorption studies suggest that COF-5 has a relatively large diffusion coefficient (0.08 cm2/s). Furthermore, exciton–exciton annihilation processes are characterized as a function of COF-5 crystallite domain size in four different samples, which reveal domain-size-dependent exciton diffusion kinetics. These results reveal that exciton diffusion in COF-5 is constrained by its crystalline domain size. These insights indicate the outstanding promise of delocalized excitonic processes available in 2D COFs, which motivate their continued design and implementation into optoelectronic devices.

A porphyrin-based two-dimensional (2D) covalent organic framework (COF) was developed by a C4 + C4 topological diagram. It was constructed by the condensation of zinc 5,10,15,20-tetra(4-aminophenyl)porphyrin (TAPP) and zinc 5,10,15,20-tetra(4-formylphenyl)porphyrin (TFPP) under typical solvothermal conditions, leading to the formation of a porphyrin-based TAPP–TFPP–COF with tetragonal micropores at a size of 1.8 nm. The resultant crystalline framework exhibited high crystallinity, excellent stability, and good porosity. Resulting from the specific π-unit stacking columnar structure and excellent organic semiconducting property of porphyrins, the TAPP–TFPP–COF shows many promising applications in optoelectronics. Notably, after doping with iodine, the conductivity of this TAPP–TFPP–COF can be greatly enhanced from 1.12 × 10–10 to 1.46 × 10–7 S cm–1. Furthermore, the nanometer-thick TAPP–TFPP–COF films were obtained using a liquid–air interface growth strategy. A spectroscopic detection device was constructed using COF thin films which displayed highly selective sensitivity toward the near infrared irradiation at 700 nm with an on–off ratio of up to 2.8 × 104. This value ranks as the highest among other COF-based and metal-organic-framework-based semiconducting materials under similar conditions. These results illustrated the enormous potential of 2D porphyrin COFs for future applications in optoelectronic devices and constituted an important step toward the development of new types of functional crystalline materials.

由于毒性，持久性和可回收的价值，必须从水溶液中选择性除去和回收银离子。在本文中，我们首先报道了通过利用氧化还原活性共价有机骨架（COF）材料作为吸附剂，可以选择性地从酸性溶液中去除银离子，从而将具有窄尺寸分布的Ag纳米颗粒（NP）装载到骨架上同时。氧化还原活性COF不仅在吸附银离子方面表现出令人鼓舞的性能，而且在低pH值下具有高选择性。随后，在系统研究氧化还原吸附机理后，发现框架内胺基的N位点负责Ag NP的产生。此外，回收利用[email protected] 该材料还可以用作新的吸附剂，通过NP作为“桥”从NP去除水中的Hg（II）离子，具有超高的原子利用率（>100％）。因此，这项工作不仅为使用氧化还原活性的COF去除金属离子提供了新颖的见解，而且为设计功能化的COF在各种领域中的潜在应用开辟了一个新领域。

Combining two or more consecutive reactions in one pot is a common approach for process development, as such a method involves cheap starting materials and allows in situ generation of a reactive intermediate, to undergo further reaction, without isolation. Herein, we report the synthesis of a vinylene-linked (−CH═CH−) covalent organic framework, COF-701, directly from acetonitrile, a cheap commodity solvent, by combining/telescoping two consecutive reactions—cyclotrimerization of nitrile and subsequent aldol condensation with aldehydes—in one pot. Acetonitrile is trimerized to generate protonated 2,4,6-trimethyl-s-triazine tautomers in situ, which undergo Aldol condensation with 4,4′-biphenyldicarbaldehyde in one pot to form crystalline COF-701. COF-701 is obtained as a polycrystalline powder and possesses permanent microporosity and a BET surface area (SABET) of 736 m2·g–1. This strategy can be further extended to generate other porous vinylene-linked frameworks.

Investigation of chirality in on-surface synthesis is of significance not only for fabricating atomically precise covalently bonded chiral species but also for unveiling chiral phenomena involving chemical reactions. In this contribution, we present the growth of single-layered homochiral 2D covalent organic frameworks (COFs) on surfaces based on a steric hindrance strategy, by which both the chiral expression of the prochiral precursor and the newly formed C═N bonds are successfully steered. When coupling a tritopic monomer with the prochiral ditopic molecule with phenyl substituents, two enantiomers of the precursor are randomly integrated in the product via variable C═N linkages, resulting in distorted hexagonal frameworks without chiral expression. After equipping the prochiral precursor with more hindered bulky substituents, highly regular homochiral 2D COFs are fabricated, in which only one of the enantiomers of the prochiral precursor is integrated, and all C═N linkages possess the same configuration. Structural analysis based on high resolution scanning tunneling microscopy images and theoretical simulations indicate that the homochiral 2D COFs are generated through an enantioselective on-surface polymerization driven by the steric hindrance effect. This result not only benefits understanding and controlling chirality in on-surface synthesis but also provides a new approach for the growth of highly regular COFs on surfaces.

The development of anhydrous proton-conducting materials is critical for the fabrication of high-temperature (>100 °C) polymer electrolyte membrane fuel cells (HT-PEMFCs) and remains a significant challenge. Covalent organic frameworks (COFs) are an emerging class of porous crystalline materials with tailor-made nanochannels and hold great potential for ion and molecule transport, but their poor chemical stability poses great challenges in this respect. In this contribution, we present a bottom-up self-assembly strategy to construct perfluoroalkyl-functionalized hydrazone-linked 2D COFs and systematically investigate the effect of different lengths of fluorine chains on their acid stability and proton conductivity. Compared with their nonfluorous parent COFs, fluorinated COFs possess structural ultrastability toward strong acids as a result of enhanced hydrophobicity (water contact angle of 144°). Furthermore, the superhydrophobic 1D nanochannels can serve as robust hosts to accommodate large amounts of phosphonic acid for fast and long-term proton conduction under anhydrous conditions and a wide temperature range. The anhydrous proton conductivity of fluorinated COFs is 4.2 × 10–2 S cm–1 at 140 °C after H3PO4 doping, which is 4 orders of magnitude higher than their nonfluorous counterparts and among the highest values of doped porous organic frameworks so far. Solid-state NMR studies revealed that H3PO4 forms hydrogen-boding networks with the frameworks and perfluoroalkyl chains of COFs, and most of the H3PO4 molecules are highly dynamic and mobile while the frameworks are rigid, which affords rapid proton transport. This work paves the way for the realization of the target properties of COFs through predesign and functionalization of the pore surface and highlights the great potential of COF nanochannels as a rigid platform for fast ion transportation.

SF6具有出色的灭弧性能和绝缘特性，已被广泛用作电绝缘介质。本文基于密度泛函理论，模拟分析了两种主要的SF6含碳分解组分（CS2和COF2）在氮掺杂的锐钛矿型TiO2（101）（N–TiO2）表面的吸附性能。结果表明，随着电导率的增加，N–TiO2对CS2表现出良好的气体敏感性，但对COF2不敏感。另外，CS2在N–TiO2上的气敏特性要强于COF2。这项工作提供了有关这种气体敏感材料的关键SF6含碳分解成分的理论信息，支持了其作为化学传感器的应用，该化学传感器用于基于分解成分分析的SF6气体绝缘设备的状态监测和缺陷诊断。

如水通道蛋白和离子通道所观察到的那样，自然界会根据单个孔或通道进化出引人入胜的分子孔，从而实现独特的生物学功能。另一方面，人造系统则探索多孔结构以在材料中构造致密的孔。在过去的一个世纪中，化学技术的进步极大地提高了我们合成多孔材料的能力。从无机单元到有机单元，从反复试验到模块制造，再到完全可预设计的孔，从苛刻的制备方案到环境合成方法的发展，这都是显而易见的。在过去的15年中，已经探索了一种基于有机和高分子化学的分子平台，以使人造孔的设计能够实现不同的孔径，形状，壁和界面。通过一类新兴的聚合物-共价有机骨架（COF），这成为可能。 COF是一类晶体多孔聚合物，可将有机单元整合到具有周期性有序骨架和轮廓分明的孔的扩展分子框架中。在过去的15年中，我们一直致力于探索COF，以设计和合成多孔结构，目的是开发化学方法，从而创造出量身定制的孔界面（Nagai， A.等。纳特社区，2011，2，536）。在此报告中，我们通过强调设计原理，合成策略以及独特的多孔特征及其影响，总结了我们用于各种孔界面的方法的一般概念。我们通过强调基于直接聚合和孔表面工程的通用策略来构造具有不同功能单元的不同孔壁，来说明孔界面设计。一个独特的特征是对这些官能团进行了预先设计和合成控制，以实现预定的组分，位置和密度，从而导致了将各种特定的孔壁界面安装到每个孔的一般方法。通过阐明界面与分子和离子之间相互作用的性质，我们展示了分层的孔隙界面结构，其范围从氢键到偶极-偶极/四极相互作用，静电相互作用，酸碱相互作用，配位和电子相互作用。我们通过公开功能设计方案和界面-功能相关性，研究了吸附和分离，催化，能量转换和存储以及质子和金属离子传输的独特性质和功能。我们预测将要解决的基本关键问题，并在设计人造毛孔以达到最终功能时显示未来的方向。这种关于孔隙界面工程的化学方法为多孔材料的开发开辟了道路，这些材料在结构和功能的预设计中仍然具有挑战性。

共价有机骨架（COF）由于其多孔性和可调的光吸收性，因此有望用作多相光催化剂。 COF的光稳定性和电荷分离对于提高光催化转化效率非常重要。在这项工作中，用苯并噻二唑单元构建了一个完全共轭的供体-受体COF，该单元表现出高稳定性并增强了电荷分离。所制备的COF可以在空气和可见光下有效地产生超氧自由基阴离子，以中等至高产率和高回收率介导光催化氧化胺偶联和硫酰胺环化成1,2,4-噻二唑。这项研究表明，具有D–A结构的完全共轭的COF具有强大的光驱动有机合成能力。

在过去的十年中，纳米医学已经对生物成像和癌症治疗产生了潜在的影响。纳米级共价有机骨架（COFs）由于其高孔隙率，功能性和生物相容性，已经发展成为具有重要应用前景的生物医学纳米材料的重要类别。 COF的高孔隙率允许以高加载效率封装独特的成像和/或治疗剂。在某些情况下，可以使用有机结构单元通过共价键合负载治疗药物和/或功能性物质。 COF的有机组成部分也可以进行后修饰，以与生物标志物特异性结合。 COF的独特特性使其成为有前途的生物成像和治疗应用纳米载体。尽管已经进行了近十年的关于COF的合理设计和制造的积极研究，但纳米级COF的治疗应用仍知之甚少。这篇综述主要总结了COF设计及其在生物医学领域中的应用方面的最新研究进展。特别地，讨论了COF的生物成像和治疗应用，包括荧光生物成像以及包括化学疗法，光动力疗法，光热疗法和协同疗法的不同治疗方法。审查还阐明了基于COF的纳米系统在尺寸控制，表面改性，生物分布，毒性和生物相容性方面面临的根本挑战。这篇综述旨在促进COF和生物医学之间的多学科研究。

Insufficient retention of water in adsorbed salivary conditioning films (SCFs) because of altered saliva secretion can lead to oral dryness (xerostomia). Patients with xerostomia sometimes are given artificial saliva, which often lacks efficacy because of the presence of exogenous molecules with limited lubrication properties. Recombinant supercharged polypeptides (SUPs) improve salivary lubrication by enhancing the functionality of endogenously available salivary proteins, which is in stark contrast to administration of exogenous lubrication enhancers. This novel approach is based on establishing a layered architecture enabled by electrostatic bond formation to stabilize and produce robust SCFs in vitro. Here, we first determined the optimal molecular weight of SUPs to achieve the best lubrication performance employing biophysical and in vitro friction measurements. Next, in an ex vivo tongue-enamel friction system, stimulated whole saliva from patients with Sjögren syndrome was tested to transfer this strategy to a preclinical situation. Out of a library of genetically engineered cationic polypeptides, the variant SUP K108cys that contains 108 positive charges and two cysteine residues at each terminus was identified as the best SUP to restore oral lubrication. Employing this SUP, the duration of lubrication (Relief Period) for SCFs from healthy and patient saliva was significantly extended. For patient saliva, the lubrication duration was increased from 3.8 to 21 min with SUP K108cys treatment. Investigation of the tribochemical mechanism revealed that lubrication enhancement is because of the electrostatic stabilization of SCFs and mucin recruitment, which is accompanied by strong water fixation and reduced water evaporation.