双网络增强自支撑多层膜的制备

通过石英晶体微天平(QCM)研究不同最外层对单体、交联剂、引发剂扩散入多层膜的结果显示,聚乙烯亚胺( PEI)为最外层的多层膜更有利于负电荷分子扩散.将(聚乙烯亚胺/聚丙烯酸)12-聚乙烯亚胺[( PEI/PAA)12-PEI]多层膜浸入带有单体、引发剂、交联剂的溶液后,经过光聚合交联与热交联后可形成自支撑膜.XPS数...     

超支化聚负离子/超支化聚正离子自组装膜的制备及反应

自1991年以来,静电吸附自组装已发展成为制备具有特定纳米微结构聚电介质多层超薄膜的有效技术。近年来,由于树枝状聚合物和超支化聚合物独特的物理化学性质,文献中已将它们与线性聚电解质一起用于静电吸附自组装过程,但完全基于超支化聚合物分子间的自组装过程还鲜见报道,超支化聚合物所具有的大量末端和内部（如叔胺基）官能团,不仅可以用于调节自组装行为及组装膜的表面形貌,     

取代超支化聚硅烷紫外光引发剂研究

以钠缩合法合成的含Si–Cl键的超支化聚硅烷(Cl-HPS)为基础,将其分别与4-羟基二苯甲酮和2-羟基硫杂蒽酮反应,制备了小分子光引发剂取代的超支化聚硅烷BP-HPS和TX-HPS.小分子光引发剂取代的超支化聚硅烷可以不同程度地扩展超支化聚硅烷的紫外吸收.采用实时红外光谱研究了它们引发己二醇二丙烯酸酯(HDDA)紫外光聚合行为.结果表明,小分子光引发剂取代的超支化聚硅烷的自由基引发效率高于未经取代的超支化聚硅烷和它们对应的小分子光引发剂的引发效率.电子自旋共振光谱研究表明,BP-HPS和TX-HPS既可以裂解产生硅自由基,也可以通过硅甲基参与的夺氢反应产生碳中心自由基.     

由聚电解质自组装多层膜制备微孔薄膜

带有相反电荷的聚电解质通过静电作用交替沉积可以得到自组装多层膜,由于这种技术可操作性强,用途广泛,近十几年来已有了大量的研究．聚电解质多层膜在一定条件下可以形成纳米孔和微米孔．Fu等研究了聚丙烯酸和聚乙烯基吡啶组成的氢键自组装多层膜在碱溶液中溶去其中的聚丙烯酸后,剩下的聚乙烯基吡啶重构形成微孔薄膜．Mendelsohn等发现将聚丙烯酸和聚烯丙基胺自组装而成的多层膜浸入pH=2．4左右的溶液中可制备微孔薄膜．但这些方法并不能使强聚电解质多层膜形成多孔结构。     

pH响应的PEG化基因传递体系

制备了苯甲酰亚胺键偶联的聚乙二醇化(PEG化)聚乙烯亚胺(m PEG-CH=N-PEI),并以还原无p H响应特性m PEG-PEI作为对照.研究结果表明,PEG链段的引入并未影响聚乙烯亚胺与脱氧核糖核酸(DNA)分子的缔合,形成了尺寸为80 nm,表面电位约为10 m V的基因超分子组装体,具有很好的生理盐稳定性.在模拟溶酶体的酸性环境下,苯甲酰亚胺键有效断裂,显示出很好的p H响应特性.Hep G2细胞培养结果表明,由于PEG链段有效屏蔽了组装体表面的正电荷,PEG化组装体的细胞毒性和内吞效率显著降低,但溶酶体酸性条件使苯甲酰亚胺键断裂,有利于组装体逃离溶酶体,因此m PEG-CH=N-PEI依然具有很高的基因转染效率,实现了基因载体细胞外稳定传递、细胞内响应解离并高效转染的功能.     

中国有机氟化合物卤键研究

综述了中国学者在有机碘代和溴代氟化物的卤键研究方面的进展.从1987至1993年,陈庆云等发现全氟碘代烷作为Lewis酸可以和胺、醚和六甲基磷酰胺等Lewis碱形成供体-受体相互作用,代表了早期研究现在被称为卤键的非共价键作用力的重要进展.2001年以来,多个研究组利用卤键开展晶体工程研究.朱士正等首次证实,全氟-α,■-二碘烷烃可以和胺、醚和六甲基磷酰胺等通过卤键形成一维扩展阵列结构,晋卫军等研究了卤键驱动的全氟碘代芳烃与氮杂芳环的共晶结构,张丹维和黎占亭等利用卤键诱导产生了双螺旋及四螺旋超分子聚合物.晋卫军等研究了C-I…p卤键在晶体工程中的应用.利用卤键诱导,王栋和万立骏等在表面实现了三角型芳香分子共组装形成二维蜂窝型阵列结构,王力彦等从两个聚合物或有机分子构筑了单层膜结构和实现了层-层自组装控制.赵新和黎占亭等合成了并入三个二氟碘甲基的三臂分子,基于氢键诱导的折叠型受体,建立了溶液相多位点卤键结合的识别模式.胡文平、龚和贵、廖良生等利用卤键提高了若干共轭有机分子的不同的材料性能.多个研究组利用卤键成功控制或提高不同类型的有机反应的选择性.     

共价键合四磺酸基铁酞菁有序多层膜电极

以玻碳电极为基础电极,经静电自组装方法将带负电荷的四磺酸基铁酞菁与带正电荷的含重氮基团的重氮树脂在电极表面进行层-层自组装,然后经紫外光照射,使铁酞菁的磺酸基与重氮树脂的重氮基发生交联反应,使层与层之间的离子键转为共价键,从而使铁酞菁在电极表面形成稳定、有序且处于分子水平的层-层构筑.用UV-Vis和IR光谱表征了组装过程,用CV方法研究了该电极的电化学性能及其对三氯乙酸的电催化还原.同时用计时电流法测定了三氯乙酸通过该类膜的扩散系数.     

基于静电自组装牛血清白蛋白复合膜的研究

利用静电层层自组装技术制备了聚乙烯亚胺-牛血清白蛋白复合膜,通过紫外-可见分光光度法监测该组装过程。牛血清白蛋白溶液的质量浓度为0.1g·L-1,聚乙烯亚胺溶液的浓度为10mmol·L-1,石英片基底在两种溶液中的浸泡时间为均为5min,每次浸泡后用水清洗3次,每次1min。多层膜在特征吸收处的吸光度随膜层数递增均匀增加,且吸光度与膜层数间呈线性关系,这表明该复合膜是均匀组装的。该组装过程具有良好的重现性。该复合膜的组装方法有望用于制备酶生物传感器。     

一种卤键高分子多层膜的层层组装及其稳定性的提高

设计合成了聚甲基丙烯酸2-(4-碘-2,3,5,6-四氟苯氧基)乙酯( PIPEMA)和聚甲基丙烯酸3-(3-吡啶基)丙酯( PPyPMA),经过层层组装和随后的紫外可见光谱的检验,发现可以在丙酮和丁酮中组装PIPEMA/PPyPMA卤键多层膜,但是当以四氢呋喃(THF)或氯仿为组装溶剂时未能获得多层膜.另外,在丁酮中...     

动态多孔海绵结构多层膜负载溶菌酶用于抗菌涂层的研究

以聚丙烯酸(PAA)和聚乙烯亚胺(PEI)为构筑单元,运用层层自组装技术制备了聚电解质多层膜.该多层膜具有独特的动态特点——经酸处理后膜内部形成海绵状通孔结构,该海绵结构在饱和水蒸气的处理下,多孔结构能够闭合,重新回到致密的膜结构.借助该种动态多层膜平台,能够简单有效地通过毛细作用力将溶菌酶负载并固定于多层膜中,为制备基于抗菌蛋白的抗菌涂层提供了新的方法.扫描电镜表征了多层膜动态变化过程,激光共聚焦显微镜表征了溶菌酶在膜内的分布情况,并测定了溶菌酶载入量及其释放动力学.进一步的抗菌测试表明该种抗菌涂层在溶菌酶和PEI的共同作用下可以有效地抑制金黄色葡萄球菌.将多层膜同时负载溶菌酶和乳铁蛋白,提升了涂层对大肠杆菌的杀菌效果.     

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.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.