TEMPO功能化共轭微孔聚合物催化氧化醇性能

将2,2,6,6-四甲基哌啶氧自由基(TEMPO)嫁接到2,5-二溴苯甲酸侧链,并与1,3,5-三乙炔苯(Ⅰ)通过Sonogashira偶联反应,合成出TEMPO自由基功能化共轭微孔聚合物CMP-3-TEMPO。利用SEM、XRD、FTIR和EPR等测试了CMP-3-TEMPO的形貌和结构组成。催化性能测试结果表明:CMP-3-TEMPO在氧气氛围、较温和条件下(80℃,常压),可将各种一级醇、二级醇以及杂原子醇氧化成相应的醛或酮化合物,转化率为70%～100%。CMP-3-TEMPO经过3次循环利用后,催化性能有所降低,可能的原因是反应过程中CMP-3-TEMPO存在局部解体,导致催化活性位点降低。     

TEMPO功能化共轭微孔聚合物作为高效醇催化氧化剂

2,5-二溴对苯二甲酸通过酰化反应得到了2,5-二溴对苯二甲酰氯(Ⅱ)。接着,中间体Ⅱ与4-氨基-2,2,6,6-四甲基哌啶-1-氧自由基(4-NH2-TEMPO)反应获得了侧链嫁接双2,2,6,6-四甲基哌啶氧自由基(TEMPO)的有机单体。然后,该有机单体与四(4-乙炔基苯)甲烷通过Sonogashira偶联反应,合成了高密度TEMPO自由基功能化的CMP-4-(TEMPO)_2共轭微孔聚合物。利用核磁共振谱(NMR)、扫描电子显微镜(SEM)、X射线衍射(XRD)、红外吸收光谱(FTIR)和电子顺磁共振谱(EPR)对所合成单体及CMP-4-(TEMPO)_2进行了表征。结果表明,CMP-4-(TEMPO)_2由微球和中空纳米管组成,具有较高的比表面积(486m~2/g),含有微孔、介孔以及大孔复合孔,孔道含有丰富的TEMPO自由基官能团,可将各种芳香醇和杂原子醇高效、高选择性地氧化成相应的醛和酮。     

高密度TEMPO功能化CMPs作为高效醇催化氧化剂

以2,5-二溴对苯二甲酸为原料，通过酰化反应，获得酰氯中间体，并与4-氨基-2,2,6,6-四甲基哌啶-1-氧自由基（4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-NH2-TEMPO）反应，获得侧链嫁接双TEMPO（2,2,6,6-tetramethylpiperidine-1-oxyl, TEMPO）自由基的有机单体。将该有机单体与四（4-乙炔基苯）甲烷通过Sonogashira偶联反应，合成高密度TEMPO自由基功能化的CMP-4-(TEMPO)2共轭微孔聚合物。利用核磁共振谱（NMR）、扫描电子显微镜（SEM）、粉末X射线衍射（PXRD）、红外吸收光谱（FT-IR）和电子顺磁共振谱（EPR）等表征手段研究了所合成单体及CMP-4-(TEMPO)2的结构特点。CMP-4-(TEMPO)2由微球和中空纳米管组成，具有较高的比表面积（486 m2/g），含有微孔、介孔以及大孔复合孔，孔道含有丰富的TEMPO自由基官能团，可将各种芳香醇和杂原子醇高效、高选择性氧化成相应的醛和酮。     

桥连结构对聚合物微球负载型TEMPO稳定性及催化氧化性能的影响

将2,2,6,6-四甲基哌啶氮氧自由基(TEMPO)通过醚键(-O-)和烷基咪唑(-(CH_2)n-im-)负载于交联聚苯乙烯微球上,分别制得PS-O-TEMPO、PS-im-C_4-TEMPO、PS-im-C_6-TEMPO和PS-im-C_(10)-TEMPO四种催化剂。采用傅立叶变换红外光谱仪(FT-IR)、元素分析仪(EA)、热重分析仪(TG)和激光粒度仪分别对催化剂的化学结构、热稳定性和溶液中的溶胀性能进行了表征。结果表明:与醚键负载相比,离子液体桥连可以使催化剂获得更高的TEMPO负载量;PS-im-C_6-TEMPO具有较高的热稳定性和较好的亲疏水性。将PS-im-C_6-TEMPO应用于序批式和固定床反应器中催化氧化苯甲醇,表现出较好的催化效果和稳定性。     

硅胶负载TEMPO催化剂的制备及其分子氧氧化肉桂醇反应过程中催化性能

构建了巯基/偶氮二异丁腈(—SH/AIBN)氧化还原引发体系,成功地实施了单体甲基丙烯酸缩水甘油酯(GMA)在微米级硅胶微粒表面引发接枝聚合,制得接枝微粒PGMA/SiO_2。然后,以4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(4-OHTEMPO)为试剂,使PGMA/SiO_2微粒表面的环氧基团发生开环反应,从而制得TEMPO固载微粒PGMA/SiO_2-TEMPO,并研究了主要因素对固载化反应的影响,同时采用多种方法对产物进行表征。最后,将PGMA/SiO_2-TEMPO与Fe(NO_3)_3组成共催化体系,催化氧化肉桂醇。结果表明,共催化体系在适宜条件下可有效地催化氧化肉桂醇,得到单一产物肉桂醛,反应16 h肉桂醛的产率可达88%。此外,该催化剂具有良好的循环使用性能。     

活性开环聚合制备pH响应性可降解聚酯

分别以N-杂环卡宾有机催化剂和金属钠有机配合物作为活性催化剂催化单体3-[(苄氧羰基)甲基]-6-甲基-1,4-二氧六环-2,5-二酮进行开环聚合,解保护后得到具有pH响应性的聚(苹果酸-乳酸)共聚物。凝胶渗透色谱(GPC)和核磁共振(1H NMR)对聚合物的平均分子量及其结构测定的结果,2种催化剂都可以得到分子量分布较窄的聚合物,但N-杂环卡宾有机催化剂的单体转化率低。     

含偶氮苯的有机微孔聚合物的合成与气体吸附

以甲基三(4-乙炔基苯基)硅烷、苯基三(4-乙炔基苯基)硅烷及4,4-二碘偶氮苯作起始单体,使用钯催化的Sonogashira-Hagihara偶联反应制备两种含偶氮苯结构的有机微孔聚合物材料。研究表明,所制备聚合物TEPM-Azo和TEPP-Azo的BET比表面积分别为205.5 m~2/g与478.5 m~2/g。对二氧化碳的吸附性能在1.13 bar/273 K条件下为1.14 mmol/g与1.17 mmol/g。此外它们还具有良好的选择吸附性能,对CO_2/N_2的选择吸附系数为48.98和53.57。     

用于识别卤素阴离子的单体和聚合物以及制备方法

正一种用于识别卤素阴离子的单体N-(对乙炔基)-苯基-2-X-四氟苯甲酰胺(X=F,Cl,Br,I)、聚合物、及其单体和聚合物的制备方法,该方法采用对氨基苯乙炔和六氟苯甲酸为主要起始原料,以N,N-二甲基-4-氨基吡啶为催化剂,终合成了目标小分子化合物N-(对乙炔基)-苯基-2-X-四氟苯甲酰     

1-正-丁氧基-2,5-二甲基-4-(4'-硝基苯基偶氮)苯的合成及表征

以对硝基苯胺、亚硝酸钠、2,5-二甲基苯酚和正溴丁烷为原料,采用重氮-偶合反应方法,合成了一种含偶氮基团的非线性生色团有机分子:1-正-丁氧基-2,5-二甲基-4-(4'-硝基苯基偶氮)苯.分别用FTIR、UV-vis和XRD对其化学结构和性能进行了分析和表征.红外光谱图中2 930、2 860 cm-1处出现的-C4H9特征吸收峰和紫外光谱中400 nm左右出现的峰是-N=N-特征吸收峰,表明1-正-丁氧基-2,5-二甲基-4-(4'-硝基苯基偶氮)苯已成功合成.X射线衍射测试结果表明1-正-丁氧基-2,5-二甲基-4-(4'-硝基苯基偶氮)苯为液晶分子.该生色团分子的成功合成为研究高性能聚合物光折变材料体系提供了良好助剂.     

新型多孔材料的合成及应用研究进展

新型多孔材料具有孔径可调节、高比表面积和可功能化设计等特点，通过不同需求对其进行结构设计和化学修饰，能够得到各种形貌和性能的新型材料，使得其在吸附与分离、储能和催化等多个领域具有较好的应用潜能。介绍有机多孔材料(HCPs、PIMs、COFs、CMPs)和有机-无机杂化多孔材料(MOFs)的合成方法及其在物质吸附分离与催化领域的研究应用，并对今后的研究热点及发展趋势进行展望。     

Flexible and UV Resistant Films Based on Thiophene‐Substituted Conjugated Microporous Polymers Bearing Alkyl Chains: Tuning of Rigidity into Soft

Conjugated microporous polymers (CMPs) are usually formed as rigid π‐conjugated networks and insoluble in common solutions which in turn have limitations in molding or process for applications due to its unprocessability. In this work, a series of CMPs containing thiophene‐moieties (SCMPs) are obtained by dibromothiophene with carbon branched chain and ethynylbenzene monomers. The solubility of the SCMPs would be significantly improved by tuning the length of alkyl chains in alkyl‐substituted dibromothiophene monomers. SCMPs products bearing different alkyl‐substituted dibromothiophene moiety exhibit an interesting transition from insolubility to solubility in most common organic solvents, which would greatly improve its processability. Taking advantage of its solubility, freestanding SCMPs films and flexible and transparent UV resistant PDMS films based on SCMPs coatings can be easily fabricated by simple coating methods. These finding may provide a possibility for future design and fabrication of soluble and processable CMPs by rational design and tuning alkyl‐substituted aromatic monomers.     

Symmetry-dependent photocatalysis of conjugated microporous polymers based on pyrene for oxygenation of sulfides with O2

To date, conjugated microporous polymers (CMPs) have been developed into multifaceted photocatalysts. Here, two CMPs based on pyrene with the linkages of thiazolo[5,4-d]thiazole (TzTz) are prepared for visible light photocatalysis. The dimension of the molecular building block’s symmetry on the property and activity of CMPs is systematically investigated. Py(4)-TzTz-CMP with a pyrene building block of D_2h symmetry gives rise to better optoelectronic property than Py(2)-TzTz-CMP with a pyrene building block of C₂ symmetry. Therefore, Py(4)-TzTz-CMP photocatalyst is endowed with superior conversions for the green light-promoted oxygenation of sulfides with O₂. Intriguingly, mechanistic explorations disclose that both superoxide and singlet oxygen are responsible for the production of the target sulfoxides. This work gives insight into the rational design of highly active CMP photocatalysts for selective chemical transformations.     

A Synthetic Approach to Star‐Like Polymers of Styrene and Butyl Acrylate by Linking Reactions using Functionalized Methacrylates

Summary: Coupling reactions between terminal functionalized polymer chains were chosen for the synthesis of star‐like polymers consisting of polystyrene and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] arms. For the preparation of terminal functionalized polymer chains a side reaction of the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) mediated free radical polymerization of methacrylates could be used successfully to convert TEMPO terminated polymers into end functionalized polymers. The number of functionalized monomer units attached to the polymer chain is directly related to the TEMPO concentration during this reaction. Different polystyrenes and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] block copolymers were functionalized with a variable number of epoxide and alcohol groups at the chain end. For the determination of the optimal reaction parameters for the coupling reactions between these polymer chains, epoxy functionalized polystyrenes were converted with hydroxy functionalized polystyrenes under basic and acidic conditions. By activation with sodium hydride or boron trifluoride star‐like polymers were synthesized under mild conditions. The transfer of the reaction conditions to coupling reactions between end functionalized polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] copolymers showed that star‐like polymers with more than 12 arms were formed using boron trifluoride as activating agent.

     

Polyurethane‐ and Polystyrene‐Supported 2,2,6,6‐Tetramethyl‐ piperidine‐1‐oxyl (TEMPO); Facile Preparation,Catalytic Oxidation and Application in a Membrane Reactor

In this contribution, the facile synthesis of two new polymer‐supported 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)‐ and polystyrene (PS)‐based TEMPO catalysts are prepared in a one‐step reaction from commercially available compounds. Both polymer‐supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co‐oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane‐supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated.     

Application of a new unimolecular initiator in the synthesis of (α,ω) ketone functionalized polystyrene in nitroxide mediated polymerization

The ketone functionalized N‐alkoxyamine, a derivative of 4‐oxo‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl (4‐oxo‐TEMPO) was synthesized and applied as an initiator in the nitroxide mediated polymerization of styrene in bulk at 120°C. In the presence of the prepared initiator: 1‐phenyl‐1‐(4‐oxo‐2,2,6,6‐tetramethylpiperidinoxy)propanone polymers with well‐defined molecular weight were obtained. By contrast, when an accelerator such as acetic anhydride (10%) was added to the system, lower control of polymerization was observed. Additionally, the functionality of polymers was evaluated on the basis of a quantitative investigation of UV–visible spectra of 2,4‐dinitrophenylhydrazone formed from the polymers and the synthesized initiator. The UV–vis spectra of the hydrazone derivatives obtained from polymers by means of 2,4‐dinitrophenylhydrazone made it possible to confirm that the polymers prepared in the presence of the ketone functionalized N‐alkoxyamine retain the ketone functionality on the polymer chain. The functionality for the obtained polymers exceeded 1 significantly. The obtained (α, ω) telechelic polymers are of great importance in the synthesis of new biohybrid materials such as bioconjugates with proteins or peptides as well as new polymer nanostructures. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

TEMPO催化醇氧化反应进展

选择性催化氧化醇类化合物为相应的醛或酮是一类重要的官能团转化反应。四甲基哌啶氧化物(TEMPO)是一种含有稳定的氮氧自由基(NO·)的有机小分子催化剂,NO·可通过自身的强选择性,在加快醛或酮转化的同时不会过氧化成为羧酸。本文阐述了TEMPO催化体系催化醇选择性氧化反应的机理,在此基础上详述了过渡金属/TEMPO、非过渡金属/TEMPO、固载化TEMPO等体系催化醇选择性氧化反应的研究情况,并探讨了TEMPO在电催化以及光催化方面的应用。指出将高活性的TEMPO催化体系改进,在发挥其高选择性、高活性优点的同时,克服其本身价格昂贵的缺点,实现催化体系的重复利用,更符合生态、绿色理念,也是未来发展的趋势。     

Cellulose-Based Hybrid Nanoarchitectonics with Silver Nanoparticles: Characterization and Antimicrobial Potency

Journal of Inorganic and Organometallic Polymers and Materials - In this study, 2,2,6,6-Tetramethylpiperidin-1-yl oxyl (TEMPO) oxidized cellulose nanofibrils (CNFs) decorated with silver...