Metal-free Synthesis of Pyridyl Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution

Developing efficient, stable and sustainable photocatalysts for water splitting is one of the most significant methods for generating hydrogen. Conjugated microporous polymers, as a new type of organic semiconductor photocatalyst, have adjustable bandgaps and high specific surface areas, and can be synthesized using diverse methods. In this work, we report the design and synthesis of a series of pyridyl conjugated microporous polymers(PCMPs) utilizing polycondensation of aromatic aldehydes and aromatic ketones in the presence of ammonium acetate. PCMPs with different chemical structures were synthesized via adjusting monomers with different geometries and contents of nitrogen element, which could adjust the bandgap and photocatalytic performance. Photocatalytic hydrogen evolution rate(HER) up to1198.9 μmol·h~(-1)·g~(-1) was achieved on the optimized polymer with a specific surface area of 312 m~2·g~(-1) under UV-Vis light irradiation(λ320 nm).This metal-free synthetic method provides a new avenue to preparing an efficient photocatalyst for hydrogen evolution.     

微孔配位聚合物作为新型储氢材料的研究

微孔配位聚合物性质独特、结构多样,具有广泛的应用前景,它已成为近几年来一个热门的研究领域。本文简要介绍该类化合物作为一种新型的储氢材料,在合成、结构和储氢性能方面的研究进展。     

共轭微孔聚合物的制备与应用

共轭微孔聚合物(CMPs)是一类有机多孔聚合物,与常规共轭聚合物或多孔材料相比,其最大的特点是既有π共轭骨架又具有大量微孔.这类材料在解决能源和环境问题方面显示出巨大的潜力,已在气体吸附、非均相催化、发光材料、化学传感器、电能存储和生物杂化物等领域显示出巨大的应用前景.目前已开发出多种用于CMPs结构单元设计与合成的新...     

Tunable Surface Area,Porosity, and Function in Conjugated Microporous Polymers

Simple inorganic salts are used to tune N‐containing conjugated microporous polymers (CMPs) synthesized by Buchwald–Hartwig (BH) cross‐coupling reactions. Poly(triphenylamine), PTPA, initially shows a broad distribution of micropores, mesopores, and macropores. However, the addition of inorganic salts affects all porous network properties significantly: the pore size distribution is narrowed to the microporous range only, mimicking COFs and MOFs; the BET surface area is radically improved from 58 m² g^?1 to 1152 m² g^?1; and variations of the anion and cation sizes are used to fine‐tune the surface area of PTPA, with the surface area showing a gradual decrease with an increase in the ionic radius of salts. The effect of the salt on the physical properties of the polymer is attributed to adjusting and optimizing the Hansen solubility parameters (HSPs) of solvents for the growing polymer, and named the Beijing–Xi'an Jiaotong (BXJ) method.     

Conjugated Microporous Polymers for Heterogeneous Catalysis

Conjugated microporous polymers (CMPs) are a class of crosslinked polymers that combine permanent micropores with π‐conjugated skeletons and possess three‐dimensional (3D) networks. Compared with conventional materials such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), CMPs usually have superior chemical and thermal stability. CMPs have made significant progress in heterogeneous catalysis in the past seven years. With a bottom‐up strategy, catalytic moieties can be directly introduced into in the framework to produce heterogeneous CMP catalysts. Higher activity, stability, and selectivity can be obtained with heterogeneous CMP catalysts in comparison with their homogeneous analogs. In addition, CMP catalysts can be easily isolated and recycled. In this review, we focus on CMPs as an intriguing platform for developing various highly efficient and recyclable heterogeneous catalysts in organic reactions. The design, synthesis, and structure of these CMP catalysts are also discussed in this focus review.     

自由基修饰共轭微孔聚合物应用于5-羟甲基糠醛选择性氧化

采用有机单体侧链嫁接2,2,6,6-四甲基哌啶氧自由基（2,2,6,6-tetramethylpiperidineoxyl,TEMPO）的策略将TEMPO嫁接到2,5-二溴苯甲酸侧链,并与四（4-乙炔基苯）甲烷通过Sonogashira偶联反应,构筑TEMPO自由基功能化共轭微孔聚合物CMP-4-TEMPO.利用核磁共振谱（NMR）、扫描电子显微镜（SEM）、粉末X-射线衍射（XRD）红外吸收光谱（FT-IR）和电子顺磁共振谱（EPR）等技术研究了所合成单体及CMP形貌和结构.催化性能测试结果表明CMP-4-TEMPO可将5-羟甲基糠醛（5-HMF）高效、高选择性氧化成高附加值2,5-二甲酰基呋喃（2,5-DFF）.CMP-4-TEMPO催化剂循环利用10次仍保持较高的转化率.提出了CMP-4-TEMPO中形成TEMPO氧正离子是实现5-HMF转化为2,5-DEF的催化氧化机理.CMP-4-TEMPO有望成为各种醇高效、高选择性氧化以及可循环利用的异相催化剂.     

Regulating Charge-Transfer in Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution

Bandgap engineering in donor–acceptor conjugated microporous polymers (CMPs) is a potential way to increase the solar-energy harvesting towards photochemical water splitting. Here, the design and synthesis of a series of donor–acceptor CMPs [tetraphenylethylene (TPE) and 9-fluorenone (F) as the donor and the acceptor, respectively], F_0.1CMP , F_0.5CMP , and F_2.0CMP , are reported. These CMPs exhibited tunable bandgaps and photocatalytic hydrogen evolution from water. The donor–acceptor CMPs exhibited also intramolecular charge-transfer (ICT) absorption in the visible region (λ_max=480 nm) and their bandgap was finely tuned from 2.8 to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also showed emissions in the 540–580 nm range assisted by the energy transfer from the other TPE segments (not involved in charge-transfer interactions), as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer was also tuned from green to red. Photocatalytic activities of the donor–acceptor CMPs ( F_0.1CMP , F_0.5CMP , and F_2.0CMP ) are greatly enhanced compared to the 9-fluorenone free polymer ( F_0.0CMP ), which is essentially due to improved visible-light absorption and low bandgap of donor–acceptor CMPs. Among all the polymers F_0.5CMP with an optimum bandgap (2.3 eV) showed the highest H₂ evolution under visible-light irradiation. Moreover, all polymers showed excellent dispersibility in organic solvents and easy coated on the solid substrates.     

Nanoparticulate Conjugated Microporous Polymer with Post-Modified Benzils for Enhanced Pseudocapacitor Performance

Conjugated microporous polymer (CMP)-based energy-storage materials were developed for pseudocapacitors. Nanoparticulate CMP (N-CMP) with an average diameter of 41±4 nm was prepared through kinetic growth control in the Sonogashira coupling of 1,3,5-triethynylbenzene with 1,4-diiodobenzene. The N-CMP is rich in a diphenylacetylene moiety in its chemical structure. Through the FeCl₃-catalyzed oxidation of diphenylacetylene moieties, N-CMP with benzil moieties (N-CMP-BZ) was prepared and showed enhanced electrochemical performance as an electrode material of pseudocapacitors, compared with CMP, CMP-BZ, and N-CMP. In model studies, the benzil was redox active and showed two-electron reduction behavior. The excellent electrochemical performance of N-CMP-BZ is attributable to the enhanced utilization of functional sites by a nanosize effect and the additional redox contribution of benzil moieties.     

含氟共轭微孔聚合物的制备及其吸附应用研究

共轭微孔聚合物由于其高的比表面积、优良的物理化学稳定性、多样的合成方法以及沿分子骨架延伸的共轭结构等特点,近几年得到广泛关注和快速发展.本工作以1,3,5-三氟-2,4,6-三碘苯作为含氟单体与1,3,5-三乙炔基苯通过Sonogashira偶联反应聚合得到含氟共轭微孔聚合物F-CMP.通过把氟原子引入到共轭微孔聚合物骨架中,F-CMP显示出良好的疏水性能,与水的接触角达到145°.得益于良好的疏水性能和适宜的孔隙结构,相比于骨架结构相似的不含氟共轭微孔聚合物（H-CMP）,F-CMP对油和有机溶剂的吸附量得到大幅提高,且显示出高的吸附速率和良好的吸附循环性.     

Polyacetylene‐Type Networks Prepared by Coordination Polymerization of Diethynylarenes: New Type of Microporous Organic Polymers

Microporous organic polymers (MOP) of a new type have been synthesised in high yields by a simple coordination polymerization of 1,3‐diethynylbenzene, 1,4‐diethynylbenzene and 4,4′‐diethynylbiphenyl catalysed by [Rh(cod)acac] and [Rh(nbd)acac] complexes. The new MOPs are non‐swellable polyacetylene‐type conjugated networks consisting of ethynylaryl‐substituted polyene main chains that are crosslinked by arylene linkers. Prepared MOP samples have a mole fraction of branching units (by ¹³C CP/MAS NMR) from 0.30 to 0.47 and exhibit the BET (Brunaer‐Emmett‐Teller) surface up to 809 m² g⁻¹ and hydrogen uptake up to 0.69 wt% (77 K, H₂ pressure 750 torr).     

A Luminescent Hypercrosslinked Conjugated Microporous Polymer for Efficient Removal and Detection of Mercury Ions

A hypercrosslinked conjugated microporous polymer (HCMP‐1) with a robustly efficient absorption and highly specific sensitivity to mercury ions (Hg²⁺) is synthesized in a one‐step Friedel–Crafts alkylation of cost‐effective 2,4,6‐trichloro‐1,3,5‐triazine and dibenzofuran in 1,2‐dichloroethane. HCMP‐1 has a moderate Brunauer–Emmett–Teller specific surface (432 m² g⁻¹), but it displays a high adsorption affinity (604 mg g⁻¹) and excellent trace efficiency for Hg²⁺. The π–π* electronic transition among the aromatic heterocyclic rings endows HCMP‐1 a strong fluorescent property and the fluorescence is obviously weakened after Hg²⁺ uptake, which makes the hypercrosslinked conjugated microporous polymer a promising fluorescent probe for Hg²⁺ detection, owning a super‐high sensitivity (detection limit 5 × 10⁻⁸ mol L⁻¹).

     

Methyllithium‐Doped Naphthyl‐Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium‐doped naphthyl‐containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol^?1 and the methyllithium‐doped naphthyl‐containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl‐containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target.     

基于能量转移机理的水溶性荧光共轭聚合物体系的设计制备及应用

水溶性共轭聚合物由于具有优异的光学性能,如强大的光捕获能力和独特的分子线效应,在化学、生物和医疗领域都有良好的应用前景。共轭聚合物受光激发后,所产生的激子可以沿着长程共轭的π骨架自由迁移,在分子骨架的任何位点都可以转移给能量受体,从而实现高效的能量传递。因此,水溶性共轭聚合物适合于构建各种能量传递体系,从而实现荧光信号放大、多色发光、活性氧产生效率提高等光学性能的优化。本文简述了基于水溶性共轭聚合物构建能量转移体系的原理和方法,总结了其在生物传感、生物成像、光动力杀菌和光动力抗癌等领域的应用,最后对水溶性共轭聚合物存在的主要问题以及未来的发展方向进行了分析和展望。     

Copper‐Free Sonogashira Coupling for High‐Surface‐Area Conjugated Microporous Poly(aryleneethynylene) Networks

A modified one‐pot Sonogashira cross‐coupling reaction based on a copper‐free methodology has been applied for the synthesis of conjugated microporous poly(aryleneethynylene) networks (CMPs) from readily available iodoarylenes and 1,3,5‐triethynylbenzene. The polymerization reactions were carried out by using equimolar amounts of halogen and terminal alkyne moieties with extremely small loadings of palladium catalyst as low as 0.65 mol %. For the first time, CMPs with rigorously controlled structures were obtained without any indications of side reactions, as proven by FTIR and solid‐state NMR spectroscopy, while showing Brunauer–Emmett–Teller (BET) surface areas higher than any poly(aryleneethynylene) network reported before, reaching up to 2552 m² g^?1.     

Conjugated Molecules and Polymers in Secondary Batteries: A Perspective

Intrinsically conducting polymers constituting a subclass of macromolecules, as well as a still growing family of large, conjugated molecules, oligomers, and polymers, have attracted research interest for the recent decades. Closely corresponding to the fascination of these materials, combining typical properties of organic polymers and metallic materials, numerous applications have been suggested, explored, and sometimes transferred into products. In electrochemistry, they have been used in various functions beyond the initially proposed and obvious application as active masses in devices for electrochemical energy conversion and storage. This perspective contribution wraps up basic facts that are necessary to understand the behavior and properties of the oligo and polymers and their behavior in electrochemical cells for energy conversion by electrode reactions and associated energy storage. Representative examples are presented and discussed, and an overview of the state of research and development is provided. Particular attention is paid to stability and related aspects of practical importance. Future trends and perspectives are indicated.     

Acid-Modulated Synthesis of Novel π-Conjugated Microporous Polymers for Efficient Metal-Free Photocatalytic Hydrogen Evolution

Simple synthetic modifications that tune the molecular structures, thereby the properties of the molecules, are of topical interest. Herein, we report the synthesis of two novel cationic rosaniline-based conjugated microporous polymers (CMPs) from identical monomers via simple acid modulation (Acetic acid and BF₃ ⋅ Et₂O). The condensation reaction of rosaniline with 2,4,6-triformylphloroglucinol in acetic acid renders β-ketoenamine-linked CMP ( CMP-A ) while changing the acid to BF₃ ⋅ Et₂O, the linkages transform to enol and undergoes BF₂-complexation, leading to boranil CMP ( CMP-B ). BF₂-functionalities in boranil CMP significantly modified the optical and functional properties compared to β-ketoenamine-linked CMP. The cationic-delocalization along with the extended π-delocalization supported by chromophoric BF₂-groups allow CMP-B to exhibit broad absorption spanning the visible to Near-Infrared region (NIR). The absorption red-edge of CMP-B appears around 1277 nm (optical band gap ∼1.58 eV) while CMP-A displays at 981 nm (optical band gap ∼1.83 eV). Most interestingly, as a photocatalyst, CMP-B catalyzes hydrogen evolution with a superior rate of 252 μmol g⁻¹ over CMP-A (100 μmol g⁻¹). It is about 2.5 times higher performance. The transient photocurrent measurements, electrochemical impedance data, and in-depth mott-Schottky analysis demonstrate that the BF₂-group in CMP-B generates photoinduced charge carriers and their migration towards the active sites for photocatalysis. These polymers show significant photocatalytic H₂ generation without any supportive metal co-catalyst. The BF₂ complexed building blocks are a unique class of metal-free photocatalysts for hydrogen evolution through green and cost-effective approach.