聚酰亚胺类共价有机骨架多孔材料的研究进展

聚酰亚胺类共价有机骨架与常规的多孔材料相比,具有较高的机械强度,良好的化学和物理稳定性以及合成的多样性以及孔尺寸的可控性,能够广泛应用于非均相催化,分离和气体储存等领域,因而有望成为一种新型的具有发展潜力的多孔材料。从聚酰亚胺类共价有机骨架中多孔材料的合成、性能等方面对近年来国内外的研究状况进行了详细的阐述,并在此基础上对该方向的前景进行了展望。     

Nano-architectures by covalent assembly of molecular building blocks

The construction of electronic devices from single molecular building blocks, which possess certain functions such as switching or rectifying and are connected by atomic-scale wires on a supporting surface, is an essential goal of molecular electronics. A key challenge is the controlled assembly of molecules into desired architectures by strong, that is, covalent, intermolecular connections, enabling efficient electron transport between the molecules and providing high stability. However, no molecular networks on surfaces 'locked' by covalent interactions have been reported so far. Here, we show that such covalently bound molecular nanostructures can be formed on a gold surface upon thermal activation of porphyrin building blocks and their subsequent chemical reaction at predefined connection points. We demonstrate that the topology of these nanostructures can be precisely engineered by controlling the chemical structure of the building blocks. Our results represent a versatile route for future bottom-up construction of sophisticated electronic circuits and devices, based on individual functionalized molecules.     

共价有机骨架储氢性能的研究进展

共价有机骨架(COFs)具有良好的热稳定性,大的表面积,高的孔隙率和极低的密度,因而显示出优异的储氢性能。重点介绍了COFs储氢性能的研究进展和目前存在的问题,提出了今后的研究重点和发展方向。     

Two-dimensional semiconducting covalent organic frameworks for photocatalytic solar fuel production

Two-dimensional covalent organic frameworks (COFs) are an emerging class of semiconducting materials for photocatalysis solar fuel production. They uniquely feature compositional and structural diversities (as opposed to inorganic semiconductors) as well as high crystallinity (as opposed to other organic semiconductors), and thereby hold great potential that is just beginning to be unveiled. Here, we provide an up-to-date account of the latest advances on the design and engineering of COF-based materials for photocatalytic H₂ production or CO₂ reduction. The review begins with an introduction of the background and fundamentals about COF-based photocatalysis. It is then followed by discussion about recent progress on their preparation, understanding of charge dynamics and strategies for improving photocatalytic performances. A short perspective on the opportunities and further directions is presented at the end.     

Reticular exploration of uranium-based metal-organic frameworks with hexacarboxylate building units

The rational reticular design of metal-organic frameworks(MOFs)from building units of known geometries is essential for enriching the diversity of MOF structures.Unexpected and intriguing structures,however,can also arise from subtle changes in the rigidity/length of organic linkers and/or synthetic conditions.Herein,we report three uranium-based MOF structures—i.e.,NU-135X(X=0,1,2)—synthesized from trigonal planar uranyl nodes and triptycene-based hexacarboxylate ligands with variable arm lengths.A new chiral 3,6-connected nuc net was observed in NU-1350,while the extended versions of the ligand led to 3-fold catenated MOFs(NU-1351 and NU-1352)with rare 3,6-connected cml-c3 nets.The differences in the topology of NU-1350 and NU-1351/NU-1352 could be attributed to the slight distortions of the shorter linker in the former from the ideal trigonal prism geometry to an octahedral geometry when coordinated to the trigonal planar uranyl nodes.     

Recent progress in the synthesis of metal–organic frameworks

Metal–organic frameworks (MOFs) have attracted considerable attention for various applications due to their tunable structure, porosity and functionality. In general, MOFs have been synthesized from isolated metal ions and organic linkers under hydrothermal or solvothermal conditions via one-spot reactions. The emerging precursor approach and kinetically tuned dimensional augmentation strategy add more diversity to this field. In addition, to speed up the crystallization process and create uniform crystals with reduced size, many alternative synthesis routes have been explored. Recent advances in microwave-assisted synthesis and electrochemical synthesis are presented in this review. In recent years, post-synthetic approaches have been shown to be powerful tools to synthesize MOFs with modified functionality, which cannot be attained via de novo synthesis. In this review, some current accomplishments of post-synthetic modification (PSM) based on covalent transformations and coordinative interactions as well as post-synthetic exchange (PSE) in robust MOFs are provided.     

Nanostructured covalent organic frameworks with elevated crystallization for (electro)photocatalysis and energy storage devices

Nanostructured covalent organic frameworks (COFs) have attracted great attentions over the past few decades due to their unique physical and chemical properties. Crystallization is sought in many application fields since it allows enhancing or even promoting properties of catalysis, energy storage and photoelectric properties. However, the crystallization process of nanostructured COFs remains to be challenging. Synthetic approaches to establish nucleation and elongation growth of COFs for controlling crystallization have drawn substantial amount of attentions. Nanostructured COFs have exhibited significant advantages when applied in (electro)photocatalysis and energy storage devices as well. In this review, recent progress in precisely design strategy of fabricating various nanostructured COFs and their applications as (electro)photocatalyzer and energy storage devices are summarized. After a brief introduction of the design principles, composition and interior architecture, the morphology of nanostructured COFs including porous and mesoporous stacked-layer structure, nanosheet structure, nanorod structure, ordered stripe arrays and various nanocomposites are thoroughly described. Reactions dedicated to crystallization process for two-dimensional (2D) COFs are discussed further. Then, the applications of nanostructured COFs as (electro)photocatalysis and energy storage devices are demonstrated. Finally, the potential advantages and challenges for the synthetic technology of nanostructured COFs materials are particularly discussed. Personal insights into the challenges and opportunities on pursuing topologies as hollow structures, dense spheres, yolk–shell structures were raised to broaden the applications.

     

共价有机框架和荧光分子的一体化自组装对神经毒模拟物的超灵敏检测

荧光分子通过非共价键作用载入到多孔矩阵中能够拓展其应用范围.本文报道了利用乳液限域的方法将带有苯并噻二唑和9,9-二己基芴基团的荧光分子1和共价有机框架(Covalent Organic Frameworks, COFs)一体化自组装,使得分子1通过CH-π作用固定在共价有机框架的骨架之上.因此这会极大地抑制荧光分子之间的π-π作用,使其表现出荧光分子单体的光学性质.更有意思的是,共价有机框架和神经毒剂模拟物(DCP)的特殊的作用,使得一体化自组装的复合物能够实现对神经毒剂模拟物高灵敏度的检测(检测限为40 ppb).而且,当前的一体化组装策略能够被拓展用于装载多种不同发射波长的荧光分子来实现白光.我们的结果提供了一种利用荧光探针分子和共价有机框架综合自组装来制备高发光效率多孔材料的新方法.     

Conceptual design of mechanisms based on computational synthesis and simulation of kinematic building blocks

Although many ingenious mechanisms have been designed, the fundamental task of conceptualizing these devices is, to a great extent, still an art. While sophisticated computational tools for dynamic analysis of mechanisms exist, hardly any computational methods exist for generalized synthesis. To develop a computational model for synthesis, a formal foundation for mechanisms design must be laid by rationalizing the process of mechanical synthesis. Rationalization in synthesis implies that complex mechanical motions can be described in terms of primitives or building blocks. In this paper, we present a matrix methodology that forms the basis for a computable approach to design synthesis. In this methodology, the continuous design space of a mechanisms domain is discretized into functional subspaces, and each subspace is represented uniquely by a conceptual building block. The matrix scheme serves as a formal means to (a) represent and reason with the building blocks at different levels of abstraction, (b) generate alternate conceptual design configurations, and (c) facilitate rapid simulation of design concepts by connecting a series of building blocks.     

MOFs材料合成及其对有机气体吸附研究进展

讨论了金属有机骨架(MOFs)材料的不同合成方法,并结合国内外研究现状分别分析了IRMOFs、MILs、ZIFs和PCN等系列MOFs材料对有机气体吸附的研究进展,比较其性能及分析研究中的难点,对MOFs材料在有机气体吸附领域的应用进行了展望。     

Tailor made synthesis of Q-TiO2 powder by using quantum dots as building blocks

A simple synthetic procedure based on ultrasonic spray pyrolysis and usage of TiO₂ quantum dots as building blocks leads to the formation of submicronic TiO₂ spheres which preserved optical and catalytic properties of the constituting elements. The methodology is not limited to semiconductor quantum dots, but provides general procedures for the rational design of novel and potentially useful composite materials.     

Rational tuning of thorium-organic frameworks by reticular chemistry for boosting radionuclide sequestration

The reticular chemistry strategy presents a powerful molecule-design tool to tailor the physical and chemical properties of metal-organic framework(MOF).In this work,we for the first time investigated the effect of organic ligands on the radionuclide sequestration(TcO₄^-)of thorium-organic framework.Through a coordination modulation technique,two novel isoreticular thorium-organic frameworks,namely Th-MOF-67 and Th-MOF-68,were obtained.Relative to the antetype MOF of Th-MOF-66 that shows extremely low uptake of ReO₄^-(a chemical surrogate of radioactive TcO₄^-),the isoreticular MOFs of Th-MOF-67 and Th-MOF-68 enable ultrahigh uptake of ReO₄^-,giving an impressively 36.8-fold or 56-fold enhancement,respectively.The adsorption capacity of Th-MOF-68 is as high as 560 mg/g,exceeding most reported adsorbents for such use.The mechanism for such exceptional outstanding performance,as unveiled by both the single crystal X-ray diffraction and theoretical calculation,is due to coordination interaction for Th-MOF-67,when a tetrazolate ligand was used,or a combined effect from both coordination interaction and anion-exchange for Th-MOF-68,if using a triazolate ligand.     

Facile synthesis of Ni-, Co-, Cu-metal organic frameworks electrocatalyst boosting for hydrogen evolution reaction

The conductive metal-organic frameworks (MOFs) are suggested as the ideal electrocatalysts for hydrogen evolution reaction (HER) because of the high utilization of metal atoms.Rational design and facile synthesis of MOFs with large specific surface area,proper metals as center,and tunable chemical components is still full of challenges.Herein,we report the facile synthesis three types of porous MOFs by regulating metal center using benzene-1,3,5-tricarboxylic acid (H3BTC) as organic ligand and have successfully synthesized the rhombic octahedral Cu-BTC,rod-shaped Co-BTC and spherical Ni-BTC materials with large specific surface area ranged in 350-500 m2 g-1.These as-prepared MOFs materials exhibit high performance of HER in 0.5 M H2SO4.Ni-BTC material exhibits the lowest overpotential of 53 mV at 10 mA cm-2 and the smallest Tafel slope of 62 mV dec-1 than those of Cu-BTC (270 mV,155 mV dec-1) and Co-BTC (123 mV,100 mV dec-1),which are much superior to these previously reported MOFs catalysts.In addition,the fast catalytic kinetic of Ni-BTC was confirmed by the smaller charge transfer resistance (Rct)value of 0.9 Ω and larger electrochemical active surface area (ECSA) of 35.5 cm2 than those of Cu-BTC (8.2 Ω,22.5 cm2) and Co-BTC (1.9 Ω,27.7 cm2).Because of the structural advantage and large ECSA,the turnover frequency (TOF) value of Ni-BTC reaches up to 0.041 s-1 at 120 mV overpotential,which is 20.5 and 2.6 times greater than that of Cu-BTC (0.002 s-1) and Co-BTC (0.016 s-1).Besides,these three types of MOFs exhibited excellent durability over 12 h.This study unfolds diverse insights into the design and facile synthesis of MOFs for electrochemical energy conversion system.     

On-surface synthesis of covalent coordination polymers on micrometer scale

On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level,with important implications for the design of new two-dimensional materials having remarkable electronic,magnetic,or catalytic properties.This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds,which prevents the ripening of defects.We show here that extended materials can be produced by a controlled co-deposition process.In particular,co-deposition of quinoid zwitterion molecules with iron atoms on a Ag(111) surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds.This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.     

Monodispersed spherical colloids of Se@CdSe: synthesis and use as building blocks in fabricating photonic crystals

Monodispersed spherical core-shell colloids of Se@Ag(2)Se have been exploited as a chemical template to synthesize Se@CdSe core-shell particles using a cation-exchange reaction. A small amount of tributylphosphine could facilitate the replacement of Ag(+) by Cd(2+) in methanol at 50 degrees C to complete the conversion within 150 min. The orthorhombic structure of beta-Ag(2)Se changed to a well-defined wurtzite lattice for CdSe. The CdSe shells could be converted back to beta-Ag(2)Se by reacting with AgNO(3) in methanol at room temperature. Because of the uniformity in size and high refractive index associated with the Se@CdSe core-shell colloids, they could serve as a new class of building blocks to fabricate photonic crystals with wide and strong stop bands.