Water‐Soluble Three‐Dimensional Polymers: Non‐Covalent and Covalent Synthesis and Functions†

Water‐soluble three‐dimensional (3D) polymers are structurally ideal for the construction of ordered porous materials for in‐situ and tunable loading and release of guests. For many years, studies on ordered porous materials have been confined to crystalline solids. Since 2014, self‐assembly has been developed as a robust strategy for the preparation of water‐soluble 3D polymers that possess defined and intrinsic porosity. Through the encapsulation of cucurbit[8]uril for aromatic dimers, ordered diamondoid supramolecular organic frameworks can be assembled from tetrahedral monomers. With [Ru(bipy)₃]²⁺‐derived octahedral complexes as precursors, cubic supramolecular metal‐organic frameworks have been assembled. One supramolecular organic framework has also been utilized to prepare the first homogeneous covalent organic framework through the [2+2] alkene cycloaddition, whereas the quantitative formation of the hydrazone bonds can be utilized to synthesize flexible porous organic frameworks. The new water‐soluble ordered and flexible polymeric frameworks are able to include drugs and biomacromolecules to accomplish in situ loading and intracellular delivery and to enrich photosensitizers and catalysts to enhance discrete visible light‐induced reactions. This review highlights the advances.     

Long-Lived Photocharges in Supramolecular Polymers of Low-Band-Gap Chromophores

Photoinduced charge separation in supramolecular aggregates of π-conjugated molecules is a fundamental photophysical process and a key criterion for the development of advanced organic electronics materials. Herein, the self-assembly of low-band-gap chromophores into helical one-dimensional aggregates, due to intermolecular hydrogen bonding, is reported. Chromophores confined in these supramolecular polymers show strong excitonic coupling interactions and give rise to charge-separated states with unusually long lifetimes of several hours and charge densities of up to 5 mol % after illumination with white light. Two-contact devices exhibit increased photoconductivity and can even show Ohmic behavior. These findings demonstrate that the confinement of organic semiconductors into one-dimensional aggregates results in a considerable stabilization of charge carriers for a variety of π-conjugated systems, which may have implications for the design of future organic electronic materials.     

Electroactive Organic Building Blocks for the Chemical Design of Functional Porous Frameworks (MOFs and COFs) in Electronics

Electroactive organic molecules have received a lot of attention in the field of electronics because of their fascinating electronic properties, easy functionalization and potential low cost towards their implementation in electronic devices. In recent years, electroactive organic molecules have also emerged as promising building blocks for the design and construction of crystalline porous frameworks such as metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs) for applications in electronics. Such porous materials present certain additional advantages such as, for example, an immense structural and functional versatility, combination of porosity with multiple electronic properties and the possibility of tuning their physical properties by post-synthetic modifications. In this Review, we summarize the main electroactive organic building blocks used in the past few years for the design and construction of functional porous materials (MOFs and COFs) for electronics with special emphasis on their electronic structure and function relationships. The different building blocks have been classified based on the electronic nature and main function of the resulting porous frameworks. The design and synthesis of novel electroactive organic molecules is encouraged towards the construction of functional porous frameworks exhibiting new functions and applications in electronics.     

Docking Strategy To Construct Thermostable,Single‐Crystalline,Hydrogen‐Bonded Organic Framework with High Surface Area

Enhancing thermal and chemical durability and increasing surface area are two main directions for the construction and improvement of the performance of porous hydrogen‐bonded organic frameworks (HOFs). Herein, a hexaazatriphenylene (HAT) derivative that possesses six carboxyaryl groups serves as a suitable building block for the systematic construction of thermally and chemically durable HOFs with high surface area through shape‐fitted docking between the HAT cores and interpenetrated three‐dimensional network. A HAT derivative with carboxybiphenyl groups forms a stable single‐crystalline porous HOF that displays protic solvent durability, even in concentrated HCl, heat resistance up to 305 °C, and a high Brunauer–Emmett–Teller surface area [SA_(BET)] of 1288 m² g^?1. A single crystal of this HOF displays anisotropic fluorescence, which suggests that it would be applicable to polarized emitters based on robust functional porous materials.     

从超分子聚合物到超分子有机框架:组装溶液相超分子结构的周期性

单体分子在溶液相自发形成周期性的网络结构,是超分子化学和分子自组装研究领域的重大挑战.多头基分子在溶液相通过分子间非共价键作用可以形成超分子聚合物.提高多头基(三头基和四头基)分子骨架的刚性,可以提高结合位点的结构预组织,进而增强分子间相互作用的协同性和多价性特征,提高自组装结构的有序性或周期性.本文综述了多头基分子自组装形成超分子聚合物的一些重要进展,介绍了二维超分子有机框架(一类新的溶液相周期性自组装网络结构研究的最新进展.     

Viologen derivatives with extended π-conjugation structures: From supra-/molecular building blocks to organic porous materials

Recently, increasing attention has been paid on extending the π-conjugation structures of viologens (1,1′-disubstituted-4,4′-bipyridylium salts) by incorporating planar aromatic units into the bipyridinium backbones. Various viologen derivatives with extended π-conjugation structures have been synthesized, including the N-termini aromatic substituted viologens, the extended π-conjugated viologens (denoted as ECVs) as well as the π-conjugated oligomeric viologens (denoted as COVs). These compounds typically exhibit interesting properties distinguished from those of an isolated viologen unit, which make them as new class of electron deficient supra-/molecular building blocks in supramolecular chemistry and materials science. In this review, we would like to highlight the recent advances of viologen derivatives with extended π-conjugation structures in versatile applications ranging from electrochromic and energy storage materials, the ECV/COV-based supramolecular self-assembly systems including the linear supramolecular polymers and 2D/3D supramolecular organic frameworks (SOFs), to the viologen-based covalent organic frameworks (COFs)/networks. We hope this review will serve as an in-time summary worthy of referring, more importantly, to provide inspiration in the rational design of novel molecules with unexplored properties and functions.     

Hexaazatriphenylene (HAT) versus tri‐HAT: The Bigger the Better?

A new hexaazatriphenylene (HAT) derivative formed by the fusion of three HAT units has been prepared and its electronic and molecular structures have been fully characterized by optical and vibrational Raman spectroscopy, electrochemistry, solid-state UV and inverse photoemission spectroscopy (UPS and IPES), and by quantum-chemical calculations. A comparative HAT versus tri-HAT study was performed. The fusion of three HAT molecules causes modifications in the optical and electrochemical properties consistent with enhanced π-electron delocalization attained in a bigger planar core. Such combined experimental and theoretical studies are useful to balance chemical design with supramolecular engineering directed to find enhanced characteristics for new organic semiconductor applications.     

水溶性三维有序超分子和共价有机聚合物

总结了近年来在水溶性三维超分子聚合物、 超分子有机框架、 超分子-金属有机框架杂化结构、 超分子-共价-金属有机框架杂化结构及共价有机框架合成、 催化和输送功能方面的研究进展, 指出了有序三维聚合物未来研究面临的挑战并展望今后的发展方向.     

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.     

Advanced supramolecular polymers constructed by orthogonal self-assembly

Large aggregates, constructed by linking together monomer building blocks via non-covalent interactions with polymer properties, are regarded as supramolecular polymers. Many kinds of non-covalent interactions, such as metal-ligand coordination, hydrogen bonding, π-π stacking, ionic interaction, and host-guest interaction etc., can be involved in the binding interactions of monomer building blocks, as well as in the modification of the side chain for the construction of variable supramolecular polymers. In this tutorial review, we summarized the reported supramolecular polymers fully- or partially-created from the combination of multiple non-covalent binding interactions, mainly of two kinds, in the orthogonal way.     

Docking Strategy To Construct Thermostable,Single‐Crystalline,Hydrogen‐Bonded Organic Framework with High Surface Area

Enhancing thermal and chemical durability and increasing surface area are two main directions for the construction and improvement of the performance of porous hydrogen‐bonded organic frameworks (HOFs). Herein, a hexaazatriphenylene (HAT) derivative that possesses six carboxyaryl groups serves as a suitable building block for the systematic construction of thermally and chemically durable HOFs with high surface area through shape‐fitted docking between the HAT cores and interpenetrated three‐dimensional network. A HAT derivative with carboxybiphenyl groups forms a stable single‐crystalline porous HOF that displays protic solvent durability, even in concentrated HCl, heat resistance up to 305 °C, and a high Brunauer–Emmett–Teller surface area [SA_(BET)] of 1288 m² g⁻¹. A single crystal of this HOF displays anisotropic fluorescence, which suggests that it would be applicable to polarized emitters based on robust functional porous materials.     

Saddle-Shaped Building Blocks: A New Concept for Designing Fully Conjugated 3D Organic Semiconducting Materials

Currently, most organic semiconducting materials (OSMs) are π-conjugated structures in one or two dimension (2D), where the lack of layer-layer π-conjugation connection greatly blocks their electron delocalization and transport. The 3D fully conjugated materials could solve this issue because they can provide efficient charge-transport pathways throughout the whole 3D skeleton, in which the suitable 3D building block is the key to the development of fully conjugated 3D OSMs. Cyclooctatetraene (COT) and its derivatives are good candidates due to their π-conjugation with 3D saddle-shaped architecture. In this Concept, we discuss the key features of saddle-shaped COT-based derivatives and their synthetic strategy, then we present the current development of using the COT derivatives as building blocks to construct the 3D fully conjugated organic small compound- and polymer-based OSMs. The properties and perspectives of these OSMs in photovoltaics, electro-catalysis and electrical conductivities are also discussed. These recent advances in the developing 3D fully conjugated materials could potentially open up a new frontier in the design of OSMs.     

Synthesis methods of organic two-dimensional materials

Among various two-dimensional (2D) materials, organic 2D polymers have attracted much attention, owing to their specific properties, such as lightweight, good flexibility, adjustable structure, and high adaptability. In recent years, more and more scientists have devoted to the research on their structural design, synthesis, characterization, and potential properties. However, in contrast to traditional one-dimensional (1D) and three-dimensional (3D) network macromolecules, the synthesis of 2D structures presents a challenge to polymer chemists, because polymerization usually takes place in a spatially random manner in solution-phase synthesis. In this review, we will focus on the synthesis methods of organic 2D materials, which have played a pivotal role since the beginning of the development of this field. We will highlight the representative examples according to the different types of polymers, including supramolecular organic 2D layers and covalent organic 2D polymers, and identify possible future research directions.     

Coordination-driven self-assembly: solids with bidirectional porosity

Coordination-driven self-assembly reactions have been used in the preparation of a variety of discrete supramolecular species, some of which have shown promise as synthetic receptors. Many highly ordered coordination polymers and porous networks have been prepared in a similar fashion. While a few of these solids are capable of the uptake of small organic molecules in the resultant molecular channels, the formation of truly porous structures has frequently been thwarted by lattice interpenetration. A strategy for the formation of porous solids that may circumvent this problem is based on the covalent construction of nanoscale macrocycles which, when eclipsed in the solid state, may lead to porous, tubular assemblies. We have incorporated these concepts toward the realization of a bidirectionally porous solid. The metal-directed, self-assembly of a conjugated, macrocyclic ligand provides a discrete, supramolecular entity in solution and the solid state. X-ray crystallographic analysis establishes that this assembly packs such that bidirectional channels are realized, and the incorporation of only ClCH2CH2Cl into the crystal lattice demonstrates that these channels are potentially suitable for the selective uptake of small organic guests.     

A Three-Dimensional Porous Organic Semiconductor Based on Fully sp2-Hybridized Graphitic Polymer

Dimensionality plays an important role in the charge transport properties of organic semiconductors. Although three-dimensional semiconductors, such as Si, are common in inorganic materials, imparting electrical conductivity to covalent three-dimensional organic polymers is challenging. Now, the synthesis of a three-dimensional π-conjugated porous organic polymer (3D p-POP) using catalyst-free Diels–Alder cycloaddition polymerization followed by acid-promoted aromatization is presented. With a surface area of 801 m² g⁻¹, full conjugation throughout the carbon backbone, and an electrical conductivity of 6(2)×10⁻⁴ S cm⁻¹ upon treatment with I₂ vapor, the 3D p-POP is the first member of a new class of permanently porous 3D organic semiconductors.     

以苝酰亚胺为构筑单元的氢键型超分子聚合物的组装与应用

以苝酰亚胺为构筑单元的氢键型超分子聚合物具有动态可逆的特征和独特的聚集体结构,呈现出许多新颖的光电功能特性,在有机太阳能电池,场效应晶体管和光收集材料等高新技术领域有着广阔的应用前景。本文在介绍苝酰亚胺衍生物的化学结构及其氢键组装特点的基础上,主要综述了近年来以苝酰亚胺为构筑单元,采用三重氢键,多重氢键以及其他形式氢键引导构筑的超分子聚合物的研究动态,这类超分子聚合物展示了丰富的组装体形貌结构,独特的性质功能以及在光电功能器件上的广阔的应用前景。最后,对其发展前景作了展望。     

Beyond Microporosity in Porous Organic Molecular Materials (POMMs)

Porous organic molecular materials (POMMs) are a novel class of porous materials that cover a wide range of organic-based molecular building blocks connected through weak supramolecular interactions, such as hydrogen bonds, π-π stacking, van der Waals and electrostatic interactions. Despite of their diverse chemical and structural nature, common features to POMMs include solution processability, crystallinity and microporosity. Herein, we focus, for the first time, on the advance of the field of POMMs beyond the archetypical microporosity. In particular, we highlight relevant examples of meso- and macroporous POMMs, as well as hierchachical ones (micro-/meso-, micro-/macro- and meso-/macroporous). We also remark some of their unique properties, and how they can be key in many applications.     

Molecular design of star-shaped benzotrithiophene materials for organic electronics

Progresses in the design and application of conjugated small molecules, oligomers and polymers have empowered rapid development of organic electronic technology as an alternative to conventional devices. Among the numerous organic electronic materials, benzotrithiophene (BTT)-based oligomers and polymers have recently come in the limelight demonstrating great potential in organic electronics as high performance photovoltaic devices, field-effect transistors, electrochromic materials, high-area capacitors and charge carrier discotic liquid crystals. In this digest, we propose an overview of the organic electronic materials based on BTT isomers, highlighting the structure-performance relationship. The results obtained so far clearly indicate that the BTT isomers are among the most promising building blocks for the development π-extended materials for optoelectronic applications in the near future.     

Recent progress on pure organic room temperature phosphorescence materials based on host-guest interactions

The inclusion of specific organic phosphorescent guest molecules by the host molecules can reduce the nonradiative transitions and engender room temperature phosphorescence emission.     

Recent progress on pure organic room temperature phosphorescence materials based on host-guest interactions

Pure organic room temperature phosphorescence (RTP) has been attracting a lot interest recently. So far, many strategies have succeeded in achieving efficient organic RTP materials by increasing the rate of intersystem crossing (ISC) and suppressing non-radiative transitions. In supramolecular chemistry, the control and regulation of molecular recognition based on the role of the host and guest in supramolecular polymers matrix, has attracted much attention. Recently, researchers have successfully achieved room temperature phosphorescence of pure organic complexes through host-guest interactions. The host molecule specifically includes the phosphorescent guest to reduce non-radiative transitions and enhance room temperature phosphorescence emission. This review aims to describe the developments and achievements of pure organic room temperature phosphorescence systems through the mechanism of host-guest interactions in recent years, and demonstrates the exploration and pursuit of phosphorescent materials of researchers in different fields.