基于环糊精包结络合作用的大分子自组装

本文综述了基于环糊精包结络合作用的大分子自组装的研究进展,包括：（1) 线型、梳型、多臂星型或超支化聚合物与环糊精或其二聚体自组装形成多聚轮烷（分子项链）、多聚准轮烷、双多聚（准）轮烷、分子管、双分子管、超分子凝胶及其应用;（2）桥联环糊精与桥联客体分子自组装制备线型或超支化超分子聚合物;（3）温度、pH值、光及客体分子刺激响应智能体系; （4) 通过亲水性的环糊精线型均聚物与含金刚烷的疏水性聚合物之间的包结络合作用来制备高分子胶束及其空心球等。     

生物医用类环糊精/聚合物(准)聚轮烷

环糊精及其衍生物具有“内疏水、外亲水”的特殊分子结构,可与许多客体分子包结形成包合物。利用环糊精与聚合物的包结作用构建稳定、结构可控并具有广泛应用前景的生物医用材料是材料及医学界研究的焦点之一。本文介绍了环糊精基(准)聚轮烷的概念及其组装驱动力,同时围绕由环糊精和聚合物组装形成的(准)聚轮烷在生物医用方面的研究包括药物载体(如超分子凝胶、超分子胶束、超分子纳米囊泡、药物键合(准)聚轮烷、刺激响应型(准)聚轮烷等)、基因载体、多重识别与靶向、形状记忆材料及其它相关领域工作进展作一概述。     

环糊精包合作用诱导聚合物自组装的研究进展

将主客体识别与聚合物自组装相结合,利用环糊精对聚合物的包合作用在溶液中诱导聚合物组装形成结构可控的纳米粒子,形成有别于基于环糊精/聚合物包合作用形成的结晶粉末和超分子水凝胶的新型材料.本文介绍了这种诱导组装方案的研究背景及最新的研究成果,综述了诱导组装的原理、特点及影响因素.研究表明,由这种方案制备的聚合物纳米粒子具有超分子动态可逆的特征,进而显示出对温度和pH等敏感的性质.该类环糊精包合作用诱导组装的聚合物超分子聚集体在生物医学材料方面具有潜在的应用价值,如用作药物和基因的可控传递释放载体.     

基于环糊精主客体包合作用构筑的聚合物

在由超分子作用构筑聚合物的研究中,环糊精因能与多种客体分子形成超分子包合物而被广泛应用。本文根据超分子构筑单元的不同,综述了两类基于环糊精主客体包合作用的聚合物:(1)通过具有环糊精及客体基团的大分子间的包合构筑的非共价键嵌段聚合物,包括不同拓扑结构聚合物的制备及其功能化;(2)通过客体基团修饰环糊精的相互包合构筑的超分子聚合物,主要涉及高聚合度超分子聚合物的制备及其研究进展。     

一种类似准[5]轮烷的β-胡萝卜素-β-环糊精包合物的制备与表征

用饱和溶液法在1∶1的乙醇—水体系中制备了β 胡萝卜素(β C)-β 环糊精(β CD)的准[5]轮烷超分子包合物.紫外可见光度法和元素分析均证明了4轮体的存在.FTIR、X 射线粉末衍射和1HNMR技术为轮烷超分子化合物的形成提供了有力的佐证.     

α-环糊精准轮烷/N-异丙基丙烯酰胺交联共聚温敏型超分子结构水凝胶的制备与表征

采用一锅法合成了甲基丙烯酰基封端的聚乳酸-聚乙二醇-聚孔酸(PLA-PEG-PLA)三嵌段大分子单体,然后再通过与α-环糊精进行超分子自组装,得到聚准轮烷.将制备的聚准轮烷悬浮在N-异丙基丙烯酰胺水溶液中,再加入适量的光引发剂,在紫外光的照射下,溶液快速固化,得到了具有超分子结构的温敏型凝胶体.采用FTIR、TG、XRD等分析手段对所得聚准轮烷及其水凝胶进行了表征.     

金纳米粒子杂化超分子水凝胶的制备与性能

在制备水溶性硫辛酸酯封端的甲氧基聚乙二醇-聚己内酯嵌段共聚物(MPEG-PCL-ALA)单层包覆金纳米粒子的基础上, 在水溶液中, 利用α-环糊精(α-CD)与单层包覆金纳米粒子的包合作用构建杂化超分子水凝胶. 透射电子显微(TEM)照片显示, 金纳米粒子的尺寸为6～8 nm. X射线衍射测试表明, 所制备的水凝胶中含有α-环糊精与MPEG-PCL嵌段共聚物包合形成的多聚准轮烷的特征衍射峰(2θ＝19.7°). 紫外-可见吸收光谱显示, 单层包覆金纳米粒子的水溶液及其与α-CD包合形成的水凝胶在525 nm处均出现表面等离子共振吸收峰, 单层包覆金纳米粒子溶液存放3个月后, 其表面等离子共振吸收峰未发生明显红移, 表明单层包覆金纳米粒子的水溶液具有较好的稳定性.     

基于环糊精二聚体与紫精聚合物的包结作用制备超分子水凝胶

制备了对苯二甲酸连接的环糊精二聚体(α,α-CD Dimer)及紫精聚合物(VP), 利用α,α-CD Dimer与VP之间的主客体识别作用构筑了一种超分子水凝胶. ¹H NMR测定结果表明α,α-CD Dimer和VP的主客体相互作用是通过α-CD空腔和VP形成包结络合物进行的. 环糊精二聚体α,α-CD Dimer和聚合物VP凝胶体系的构筑受环糊精二聚体类型的影响, 同时该超分子水凝胶对有竞争作用的客体分子表现出响应性, 该超分子水凝胶在竞争性客体分子存在的条件下, 可发生小分子诱导的凝胶与溶胶转化行为. 此外, 该凝胶体系还具有良好的热稳定性.     

利用可逆共价键pH响应性制备聚轮烷

合成了具有可逆酰腙键的2,4-二硝基苯甲醛封端的哑铃型聚乙二醇衍生物. 在60 ℃时将水溶液的pH值调节至酸性, 哑铃型聚合物上的酰腙键发生可逆的“断开”和“生成”. 在这个可逆过程中, 溶液中的α-环糊精逐步与聚乙二醇内含复合. 由于环糊精具有较强疏水作用的内部空腔, 可以与聚乙二醇形成稳定的内含结晶复合物, 在这种超分子作用力下, 哑铃型聚乙二醇衍生物的分子链上会动态地穿入更多的α-环糊精, 最终形成聚轮烷. 综合液体核磁共振、粉末X射线衍射、固体碳-13交叉极化/魔角自旋核磁共振及差示扫描量热分析结果证明, 这种利用可逆共价键pH响应性制备聚轮烷的方法是可行的. 与传统的聚轮烷制备方法不同, 这种利用动态的可逆共价键制备聚轮烷的方法并不需要预先合成准(聚)轮烷.     

基于环糊精的(准)聚轮烷研究进展

环糊精聚轮烷作为超分子化学的重要成员由于可潜在应用于分子机器、组织工程支架、人体生物传感器及药物控制释放载体等智能生物材料已成为国际化学及高分子科学的一个热点.本文介绍了基于环糊精的(准)聚轮烷最新研究进展,包括(准)聚轮烷合成新方法,聚轮烷的多种类型(如嵌段型、金属软连接型、星形、pH敏感型、侧链型、聚轮烷聚集体等),以及(准)聚轮烷形成机理研究,并进一步探讨了该领域的研究前景及有待解决的问题.     

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.