以实践应用为导向的石墨烯非共价功能化

石墨烯的湿法化学修饰,主要包括共价及非共价两种,是目前广泛采用的宏量功能化策略,亦是解决其易团聚充分发挥纳米性能的重要修饰方法。 非共价功能化因可同时保持原有及引入物质的物化性质,并可充分发挥协同作用,近年来已受到比共价修饰更多的研究关注,并已在生物科学与技术、可持续能源储存及转化、医疗和复合材料等诸多领域得到了广泛的应用。在这里,我们精心遴选了近三年的文献,综述了以应用为导向的石墨烯非共价功能化的构建策略,期望文中涉及的湿法组装策略能为进一步构建性能提升的新材料提供参考。     

功能化石墨烯在第三代电化学生物传感器中的应用研究

石墨烯因具有大的比表面积、完整的?-?共轭结构及良好的生物相容性和优良的导电性能等特性,受到电化学研究者们的广泛关注.然而在应用过程中,本征态石墨烯存在水溶性差、与介质的相互作用较弱、易团聚等问题.通过使用非共价、共价、氮掺杂修饰的方法对石墨烯进行功能化,较好地改善了这一问题,扩展了石墨烯在电化学领域的应用.自2009年首次将功能化石墨烯应用于第三代电化学生物传感器的研究以来,近几年相关研究呈增多的态势.本文系统总结了自2009年以来,功能化石墨烯作为新型电极修饰材料在第三代电化学生物传感器研究中的相关工作,并阐述了其在该领域发展中遇到的问题.     

石墨烯衍生物的合成及应用

石墨烯是继富勒烯、碳纳米管之后碳纳米材料研究领域涌现出来的又一颗崭亮新星。表面功能化处理是石墨烯强化其优异的本征性能和赋予其他新颖功能的主要技术途径。近年来,研究者相继开发了一系列石墨烯改性与功能化的技术方法,制备得到了多种结构特异、组成丰富和性能独特的石墨烯衍生物。本文基于该领域研究的最新进展,从石墨烯化学的角度出发,综述了石墨烯主要衍生物的制备方法以及应用途径,其中主要包括石墨烯的加氢与氟化、有机功能化、聚合物对石墨烯的共价与非共价修饰、石墨烯衍生物在生物医药研究领域的应用等,并对目前相关研究领域的发展趋势进行了总结和展望。     

点击化学法修饰氧化石墨烯及其在高分子中的应用研究

点击化学是一种操作简单方便、灵活高效的化学合成方法,对石墨烯的改性具有高效和活性位点可控等特点,是一种新型高效修饰石墨烯的改性法。本文结合点击化学改性石墨烯的特点及在高分子中的应用,将点击化学功能化修饰石墨烯分为共价键点击功能化和非共价键点击功能化,其中共价键结合又可细分为边缘点击功能化改性和表面点击功能化改性。本文介绍了叠氮功能改性剂的制备方法及其修饰石墨烯的点击反应原理,总结了点击功能化石墨烯及氧化石墨烯高分子复合材料的功能特性和应用前景。     

增强功能化石墨烯分散性及热稳定性的共价修饰策略

氧化石墨烯(GO)是石墨烯应用过程中非常重要的前驱体之一,然而源于其热不稳定性且只能分散于高极性溶剂中,限制了它的进一步发展。基于氧化石墨烯的共价功能化技术可以较好地克服以上缺点,对于发展具有阻燃性能的新型复合材料具有重要的理论及实践意义。本文针对GO上不同反应基团,综述了利用共价化学修饰策略制备具有高分散性及热稳定性的功能化石墨烯纳米材料的研究进展。     

层间共价增强石墨烯材料的构筑、性能与应用

大批量石墨烯可控制备技术的逐渐成熟为实现其宏观组装和应用提供了基础。在众多的组装策略中,调节石墨烯层间的界面相互作用可以直接影响组装体的力学、电学、热学以及渗透等性质,具有重要的意义。石墨烯片层间以共价键连接的层间共价石墨烯材料以其可调的层间距、较强的层间作用力、丰富的功能化、以及可能的原子构型重排等特性,受到了广泛的关注和深入的研究。相比于其他非共价的键合手段,共价连接是一种更为牢固的枢纽。本文中我们将总结讨论层间共价石墨烯材料的构筑方法、性能以及应用。在构筑方法中,依据石墨烯本身的制备方法分为氧化还原法以及化学气相沉积法,而在氧化还原法中,以其宏观材料的形貌分为纸状和纤维状来讨论。接着,我们重点介绍了层间共价对其力学和电学性能的影响,并概述了此类宏观组装体材料的应用。层间共价石墨烯材料继承了石墨烯自身优异的特性,同时也具有宏观组装所赋予的性能,有望在多个领域得到广泛的应用。     

湿法纺制石墨烯纤维：工艺、结构、性能与智能应用

石墨烯纤维是由石墨烯片层通过组装过程形成的宏观一维材料。其具有较好的耐热性、导热性、导电性以及轻质高强等优点,是实现高品质、功能化纤维的重要突破口。石墨烯纤维在超轻导线、可穿戴储能、传感、生物电极等领域具有广阔应用前景。目前,湿法纺制技术是石墨烯纤维的最主要制备手段,与现有的化学纤维制备过程兼容,是最有望实现规模化制备高品质石墨烯纤维的技术。本文首先介绍了湿法纺制石墨烯纤维工艺中的关键步骤,重点讨论了制备技术与石墨烯纤维结构之间的关系。论述了提升纤维性能的相关策略,总结了石墨烯纤维在功能/智能纤维领域应用。并对提升石墨烯纤维性能的关键问题进行总结阐述,展望了石墨烯纤维的发展前景。     

β-环糊精功能化石墨烯的制备及热稳定性的增强

采用2种有机合成路线制备了结构不同的环糊精共价修饰的功能化石墨烯纳米材料,并利用FTIR,XRD,TEM,SEM和TG分析等技术对产物的结构和性能进行了表征.结果表明,2种石墨烯基纳米材料由于合成策略的不同导致溶剂分散性能存在一定的差别,但它们均可均匀分散于N,N-二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)和乙二醇中.同时,环糊精的引入使其热学稳定性显著提高.该材料在阻燃型复合材料等领域中具有一定的潜在应用价值.     

羧基功能化石墨烯增强TiO_2光催化产氢性能（英文）

利用半导体光催化剂(Cd S、g-C_3N_4、TiO_2等)产氢是将太阳能转换为氢能以满足未来能源需求的前瞻性策略之一。在众多光催化剂中,TiO_2因其合适的还原电位和出色的化学稳定性而备受关注。然而,TiO_2受光激发产生的电子和空穴容易发生猝灭而表现出有限的光催化性能。由于具备优异的导电性和稳定性,石墨烯可以作为一种有效的电子助剂加速光生电子的传输,进而提高TiO_2的产氢性能。但是,在光催化反应中,除了光生电子的快速转移外,石墨烯表面的界面产氢反应也非常重要。因此,有必要进一步优化石墨烯的微观结构(功能化石墨烯),以提高石墨烯基TiO_2光催化剂的产氢性能。通常,石墨烯的功能化是一个可以在石墨烯表面上引入产氢活性位点的有效策略。与非共价功能化(例如在石墨烯表面上加载Pt,MoSx和CoSx)相比,石墨烯的共价功能化可以通过化学反应将产氢活性位点与石墨烯表面的官能团相结合,并形成强相互作用,有利于界面的产氢反应。本文将开环和酯化反应制备的羧基功能化石墨烯(rGO-COOH)成功地通过超声辅助自组装法修饰TiO_2得到高活性的TiO_2/rGO-COOH光催化剂。傅立叶变换红外(FTIR)光谱显著增强的―COOH官能团特征峰、X射线光电子能谱(XPS)中的峰面积变化和热重(TG)曲线的质量变化证实了GO向rGOCOOH的成功转变。X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、XPS和紫外可见漫反射光谱(UV-Vis)等一系列表征可证明TiO_2/rGO-COOH光催化剂的成功合成。光催化产氢测试结果表明TiO_2/rGO-COOH样品表现出较高的产氢活性(254.2μmol·h~(-1)·g~(-1)·),分别是TiO_2/GO和TiO_2的2.06和4.48倍。光催化活性提高可归因于羧基功能化石墨烯中具有优异亲核性的羧基可以富集氢离子,并作为有效的产氢活性位点,显著地提高TiO_2的界面产氢反应速率。这项研究为我们在光催化产氢领域中开发高活性石墨烯负载的光催化剂提供了新的思路。     

羧基功能化石墨烯及其壳聚糖复合膜的制备与性能

采用Hummers法制备氧化石墨,化学分散法制备羧基功能化石墨烯。采用FT-IR、XRD对产物进行表征;用静电自组装法将其与壳聚糖（CS）复合制备复合膜,对复合膜的荧光性能及其修饰玻碳电极对葡萄糖的电催化氧化还原性能进行了研究。结果表明：制备的功能化石墨烯含有羧基;壳聚糖-石墨烯复合膜具有光致发光性能;复合膜修饰玻碳电...     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.