共价有机框架在能源存储及转化中的研究进展

共价有机框架（Covalent Organic Frameworks,COFs）是一类由有机结构单元通过共价键连接形成的多孔框架晶体材料,具有密度低、比表面积大和热稳定性高等特点,在分子吸附与分离、传感、催化、光电器件等领域存在着广阔的应用前景.近年来,基于其固有结构特点,二维COFs在能源领域中的应用潜力也逐渐引起了科学界的关注.本文主要综述了二维COFs材料在能源存储（锂离子电池、锂硫电池、超级电容器、燃料电池）和能源转化（水分解反应以及CO₂还原反应）等方面的研究进展,并对其研究前景进行了展望.     

功能性共轭多孔聚合物材料

有机多孔聚合物(organic porous polymers,OPPs)材料是一类由强共价键将不同几何构型的有机分子砌块链接而成的多维度的多孔网络骨架材料,近年来成为多孔材料发展的一个新方向.按其结构的有序程度划分,OPPs包括无定型(如CMPs,HCPs,PIMs,PAFs等)和晶态(如COFs,CTFs)多孔聚合物两大类.因具有质轻、较大的比表面积、优异的多孔特性、稳定性好、结构与功能可预先设计和精确调控等优点,OPPs在气体存储/分离,非均相催化,光电转换,化学/生物传感,能量存储与转换等诸多领域有着广泛的应用前景.基于"自下而上"的构筑策略,以一种或多种具有特定功能的有机共轭分子为构筑单元,通过其分子间的自聚或共聚来实现二维、三维共轭高分子网络的可控构筑,发展了一系列具有优异光电、催化性能的功能性有机骨架材料.本文总结了近年来作者所在课题组报道的以功能性共轭有机分子为反应单元,自下而上构筑共轭多孔聚合物材料的战略和方法,主要探索了其结构特征以及在光电转换和非均相催化领域等的初步应用.     

共价有机多孔聚合物合成新策略

共价有机多孔聚合物(COPs)是由有机结构单元通过共价键连接而形成的一类具有微孔或者介孔结构的新型高分子多孔材料, 在能源、物质吸附与分离、气体存储、光电器件、多相催化以及化学/生物传感等方面展现出巨大的应用潜能. 尽管其合成方法众多, 合成单体多样, 产物结构稳定, 但是传统方法合成的有机多孔材料大多是无定型的, 结构难以控制, 且通常不溶不熔, 很难再加工. 为了解决这些问题, 近年来很多新的合成方法和合成策略被开发出来, 为共价有机多孔聚合物的进一步发展指明了方向. 本文将对这些最新的研究进展做一简要的介绍.     

基于间苯三酚及其衍生物构筑新型有机多孔材料

有机多孔材料凭借其高比表面积、孔道可调性、易功能化修饰和结构多样性等特征,在催化、能源、吸附与分离等多个领域中展现了巨大应用潜力.对多官能度有机化合物单体以及高效聚合反应的巧妙应用,为新型有机多孔材料的创制提供了强有力的工具,成为该领域的研究热点.以C₃对称型的间苯三酚及其衍生物为例,综述了其在一系列新型有机多孔材料高效构筑中的最新研究进展.     

碳碳键链接的二维共价有机框架研究进展

二维共价有机框架(Two-dimensional Covalent-Organic Frameworks, 2D COFs)是指一类由π-共轭构筑单元通过共价键连接形成的具有二维拓扑结构的晶态多孔材料.由于其独特的周期性多孔结构、高比表面积、优异的稳定性等特点在离子传输、光电材料、催化等领域展现出了巨大的应用潜力.其中,碳碳键链接的共价有机框架因兼具优异的稳定性和良好的结晶性,被认为是最具有前景的二维聚合物材料之一.近年来,基于不同的设计原则和合成策略涌现出了许多具有不同结构和优异性能的碳碳键链接共价有机框架.在这篇综述中,按照构筑单元的拓扑结构对碳碳键链接共价有机框架进行分类,并归纳总结了迄今为止C=C和C—C键链接的二维共价有机框架在合成方法、结构创新、性能提升以及实际应用领域的研究进展.该综述旨在为相关领域的研究人员更好地设计和合成具有多种功能的多孔结晶材料提供参考,从而促进碳碳键链接共价有机框架材料在光电领域的进一步发展和应用.     

一步碳化多孔有机材料制备多孔碳及其性能的研究

开发并利用清洁的、可再生的能源是解决环境污染问题和能源短缺的有效方法.碳化含碳量较高的多孔有机材料制备的多孔碳,具有较高的比表面积,良好的物化稳定性,优良的机械性能等优点,在清洁能源的存储、分离、能量的存储与转化领域有广泛的应用.常见的由多孔有机材料制备多孔碳的方法主要是非活化碳化法和活化碳化法.不同的制备方法得到的多孔碳形貌,孔结构各不形同.多孔碳材料自身的结构性质可以影响其应用.合理的设计并调控多孔碳的“孔”,发挥孔尺寸的“筛分效应”可以有效地对气体进行存储和分离.在锂电等能量转化领域,“限域效应”是影响锂电性能的重要因素.多孔碳材料中较小的孔可以限域活性成分,而较大的孔可以快速传输,两种孔的协同效应可以使锂电性能大大提升.本综述系统地归纳了一步碳化多孔有机材料制备多孔碳的方法及其优势,详细地介绍了其在气体吸附、存储、分离以及电化学等领域的应用.最后,结合多孔碳材料的研究现状,提出由多孔有机材料制备多孔碳材料所面临的挑战,同时也展望了多孔碳材料的应用前景.     

共价有机框架材料在光催化领域中的应用

共价有机框架(COFs)材料是有机构筑基元通过共价键连接而形成的晶态有机多孔材料. COFs具有孔道结构规整、 及比表面积高等特点, 被广泛地应用于气体储存与分离、 催化、 传感、 储能及光电转化等领域. 将具有可调吸光能力的有机构筑基元引入到COFs中, 可使其展现出强大的光催化潜力. 近年来, COFs在光催化领域中发展迅猛. 本文总结了COFs在光催化产氢、 光催化二氧化碳还原、 光催化有机反应以及光催化污染物降解等方面的研究进展, 并展望了其在光催化领域的应用前景.     

多孔骨架固定分子催化剂催化CO2加氢制备甲酸研究进展

近年来, 大气中CO₂含量急剧增加, 导致了严重的温室效应. 将CO₂作为C1资源转化为燃料或精细化学品引起了越来越多的关注. 开发高效、 稳定、 可回收利用的催化剂成为CO₂资源化利用的关键. 在众多的CO₂加氢催化剂中, 功能性多孔骨架材料固定型分子催化剂展示出优异的性能, 成为研究的热点之一. 功能性骨架材料, 如多孔有机聚合物(POPs)、 共价有机骨架(COFs)和金属有机骨架(MOFs), 具有比表面积大、 热稳定性高和可调性等特点, 在设计合成催化剂方面发挥着重要作用. 本文介绍了POPs/COFs/MOFs多孔骨架材料固定分子催化剂的开发及在催化CO₂合成甲酸领域的最新进展.     

有机多孔催化研究进展

有机多孔材料POPs (Porous Organic Polymers)成为近年来的研究前沿之一. 有机多孔材料包括非晶型(如CMP, HCP, PIM等)和晶型(比如COFs等)有机多孔材料两类, 它们具有优异的孔性质、较大的比表面积、稳定性好、重量轻以及易于功能化等诸多优点, 被广泛应用于气体存储分离、传感、有机光电和多相催化等重要领域. 这里对有机多孔材料在多相催化领域中的应用做一综述. 目前, 有机多孔催化领域的研究工作主要有三类: 一类是通过“自下而上”策略将金属-配体类催化剂嵌入有机多孔骨架来构建多相催化剂; 另一类是将有机多孔材料作为载体, 通过后修饰方式负载金属纳米颗粒构建多相催化剂; 最后一类是通过“自下而上”策略将不含金属的有机小分子催化剂嵌入材料骨架来构建多孔有机催化剂. 受益于其结构的优越性, 有机多孔材料在多相催化中表现出优异的催化性能. 借鉴于均相催化的发展, 具有催化活性的有机多孔材料在多相催化领域中的应用也将会有更大的发展空间.     

共价有机骨架材料设计及其在分离领域的应用

共价有机骨架(COFs)材料是由有机小分子单体通过共价键连接形成的结晶多孔聚合物。与传统的线性聚合物不同的是,COFs可以在二维和三维空间上对其骨架结构进行控制,从而合成具有高度有序的刚性多孔结构,并且能够调节骨架的化学和物理性质。这种由COF形成的纳米级孔道和空间为分子存储、释放和分离提供了理想的环境。因此它在能量储存、分离、催化等领域有着广泛的应用前景。本文综述了近年来COFs材料的研究进展,主要包括材料的合成策略及其在分离领域的应用,并对COFs材料未来的发展方向进行了展望。     

Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds

Porous organic materials are an emerging class of functional nanostructures with unprecedented properties. Dynamic covalent assembly of small organic building blocks under thermodynamic control is utilized for the intriguingly simple formation of complex molecular architectures in one‐pot procedures. In this Review, we aim to analyze the basic design principles that govern the formation of either covalent organic frameworks as crystalline porous polymers or covalent organic cage compounds as shape‐persistent molecular objects. Common synthetic procedures and characterization techniques will be discussed as well as more advanced strategies such as postsynthetic modification or self‐sorting. When appropriate, comparisons are drawn between polymeric frameworks and discrete organic cages in terms of their underlying properties. Furthermore, we highlight the potential of these materials for applications ranging from gas storage to catalysis and organic electronics.     

Supramolecular Reassembly of Self‐Exfoliated Ionic Covalent Organic Nanosheets for Label‐Free Detection of Double‐Stranded DNA

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.     

Precisely Controlled Multidimensional Covalent Frameworks: Polymerization of Supramolecular Colloids

Rapid and selective removal of micropollutants from water is important for the reuse of water resources. Despite hollow frameworks with specific functionalized porous walls for the selective adsorption based on a series of interactions, tailoring a stable shape of nanometer- and micrometer-sized architectures for the removal of specific pollutants remains a challenge. Here, exactly controlled sheets, tubes, and spherical frameworks were presented from the crosslinking of supramolecular colloids in polar solvents. The frameworks strongly depended on the architecture of original supramolecular colloids. As the entropy of colloids increased, the initial laminar framework rolled up into hollow tubules, and then further curled into hollow spheres. These shape-persistent frameworks showed unprecedented selectivity as well as specific recognition for the shape of pollutants, thus contributing to efficient pollutant separation.     

Vinylene-Linked Covalent Organic Frameworks (COFs) with Symmetry-Tuned Polarity and Photocatalytic Activity

The polarity of a semiconducting molecule affects its intrinsic photophysical properties, which can be tuned by varying the molecular geometry. Herein, we developed a D_3h-symmetric tricyanomesitylene as a new monomer which could be reticulated into a vinylene-linked covalent organic framework (g-C₅₄N₆-COF) via Knoevenagel condensation with another D_3h-symmetric monomer 2,4,6-tris(4′-formyl-biphenyl-4-yl)-1,3,5-triazine. Replacing tricyanomesitylene with a C_2v-symmetric 3,5-dicyano-2,4,6-trimethylpyridine gave a less-symmetric vinylene-linked COF (g-C₅₂N₆-COF). The octupolar conjugated characters of g-C₅₄N₆-COF were reflected in its scarce solvatochromic effects either in ground or excited states, and endowed it with more promising semiconducting behavior as compared with g-C₅₂N₆-COF, such as enhanced light-harvesting and excellent photo-induced charge generation and separation. Along with the matched energy level, g-C₅₄N₆-COF enabled the two-half reactions of photocatalytic water splitting with an average O₂ evolution rate of 51.0 μmol h⁻¹ g⁻¹ and H₂ evolution rate of 2518.9 μmol h⁻¹ g⁻¹. Such values are among the highest of state-of-the-art COF photocatalysts.     

共价有机框架材料固定化酶的研究进展

共价有机框架（Covalent Organic Frameworks, COFs）是一种新型的多孔材料,具有结构规整、骨架稳定、孔径结构可调等特点,被视为固定化酶的理想载体。我们主要总结了近10年来COFs材料作为载体,通过物理吸附、共价连接、包埋的固定化策略制备固定化酶的研究进展与应用,并讨论了COFs材料在酶固定化领域所面临的机遇和挑战。     

An Ultrastable Crystalline Acylhydrazone-Linked Covalent Organic Framework for Efficient Removal of Organic Micropollutants from Water

As an important member of crystalline porous polymers, acylhydrazone-linked covalent organic frameworks (COFs) have gained much attention in recent years. However, the low structural stability imparts a limit on their practical applications. To tackle this problem, we report a simple strategy to increase the chemical stability of acylhydrazone-linked COFs by incorporating azobenzene groups in the conjugated framework. Through reinforcing the π-π stacking interactions between the adjacent layers with increased π-surface, it is surprising to find that the resulting materials exhibit extreme stability in harsh environments, such as in strong acid, strong base, aqueous educing agent and boiling water, even exposed to air for one year. As a proof-of-concept, such frameworks have been used to remove various organic micropollutants such as antibiotics, plastic components, endocrine disruptors, and carcinogens from water with high capacity, fast speed and excellent reusability over a wide pH range at environmentally relevant concentrations. The results provide a new avenue to significantly enhance the stability of COFs for practical applications.     

含低聚醚链共价有机骨架薄膜材料的制备及其离子分离性能

用2,5-二(2-甲氧基-乙氧基)对苯二甲酰肼(BMTH)和1,3,5-三甲氧基-2,4,6-三甲酰基苯(TpOMe)缩聚,基于界面聚合法,在多孔三氧化二铝(AAO)基底上制备出一种二维共价有机骨架(COF)膜TpOMe-BMTH,并研究了所得膜材料对锂、镁离子的分离性能。结果显示,TpOMe-BMTH/AAO膜具有高的结晶性和良好的稳定性,并表现出优异的金属离子选择性,在LiCl(0.1 mol·L^-1)和MgCl₂(0.1 mol·L^-1)组成的二元混合离子体系中,对Li⁺/Mg²⁺的分离因子高达258。基于密度泛函理论的平面波赝势方法计算表明,材料孔道中的富氧低聚醚链对 Li⁺和 Mg²⁺的结合能分别为-282.69和-13.46 kJ·mol^-1,使材料表现出强的亲锂特性,促进了Li⁺沿着COF膜的一维孔道进行吸附扩散,最终实现锂、镁离子的高效分离。     

己烯雌酚印迹共价有机骨架材料的制备及其性能探究

采用一步法制备己烯雌酚印迹共价骨架材料(MICOFs),将其作为固相萃取填料,结合高效液相色谱法,用于实际样品中己烯雌酚的分离与检测。以己烯雌酚为模板分子,三醛基间苯三酚(Tp)、对苯二胺(Pa-1)为功能单体,通过席夫碱反应合成印迹共价骨架材料。通过傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、X-射线粉末衍射(XRD)对聚合物进行了表征,动力学和选择性吸附实验对MICOFs的吸附性能进行评价。结果表明:聚合物具有规则的形貌、良好的晶型,对己烯雌酚具有较高的吸附量(89.05 mg/g),能够快速达到吸附平衡(25 min),同时对模板分子具有良好的选择性。为己烯雌酚的分离提供一种新材料。     

卟啉框架材料在光催化领域的应用

卟啉分子对可见光具有较强吸收能力,被广泛应用于光催化和光敏化材料的设计开发。 基于卟啉单元设计构筑框架结构材料,可以借助框架结构的大比表面积和可调控孔结构,实现对卟啉单元光物理化学性质的修饰和调控,达到提高材料光催化量子产率和光催化选择性的目的。 本文综述了卟啉基金属有机框架材料(MOFs)、卟啉基共价有机框架材料(COFs)、以及卟啉基多孔共价有机聚合物(COPs)在光催化领域的研究进展,通过归纳需要解决的关键问题,对卟啉框架材料的未来发展进行了展望。     

Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations

Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.