叶立德活性聚合制备基于聚亚甲基的大分子单体

利用叶立德活性聚合方法制备了两种基于聚亚甲基的大分子单体. 其中一种是以叶立德活性聚合制备的主链链端含有羟基的聚亚甲基(PM-OH)为原料, 通过链端羟基的基团转换, 得到链端含有甲基丙烯酸酯基的大分子单体. 另一种则是以硼烷-四氢呋喃(BH₃-THF)和二乙烯基苯反应得到的三烷基硼中间体为催化剂和引发剂, 然后进行叶立德活性聚合, 再经过二水合氧化三甲胺(TAO)的氧化, 最终得到基于聚亚甲基的一端含有羟基另一端含有苯乙烯基的大分子单体. 通过高温核磁氢谱、傅立叶红外光谱和高温凝胶色谱法表征了这两种大分子单体的链结构和分子量及其分布.     

原子转移自由基聚合合成聚乙烯胺大分子单体及其共聚反应研究

以水为反应介质, 采用原子转移自由基聚合(ATRP), 在70 ℃下合成了末端为溴原子的聚丙烯酰胺预聚体(PAM-Br). 利用水相凝胶渗透色谱(GPC)对PAM-Br的相对分子质量和分子量分布进行了表征, 结果表明: 单体浓度、单体与引发剂物质的量之比和反应时间对PAM-Br的分子量及其分布有较大的影响, 在较低AM单体与引发剂物质的量比条件下, 其聚合过程符合ATRP的基本规律. 进而使PAM-Br预聚体末端的溴原子与甲基丙烯酸(MAA)进行亲核取代反应, 得到了末端带有不饱和双键的大分子单体(MAA-PAM). 并利用霍夫曼降解制备出了部分胺解的聚乙烯胺(MAA-PVAm)大分子单体, 其结构由傅里叶变换红外(FTIR)和核磁共振仪(NMR)的表征得到了确定. 以得到的大分子单体为反应性分散稳定剂, 与苯乙烯在乙醇/水的混合介质中进行分散共聚反应, 制得了聚苯乙烯接枝MAA-PVAm (PS-g-PVAm)复合微球, 由扫描电子显微镜(SEM)观察发现: 微球保持规整的球形结构, 粒径分布均一, 有较好的单分散性.     

ATRP合成大分子单体法制备核壳结构微球

以α-溴代丙酸乙酯(EPN-Br)为引发剂, N,N, N′,N″,N″-五甲基二亚乙基三胺(PMDETA)为配体,使甲基丙烯酸叔丁酯进行原子转移自由基聚合,合成了端基带溴原子的聚甲基丙烯酸叔丁酯(PtBMA-Br)大分子中间体,通过其与甲基丙烯酸的亲核取代反应,得到了末端C=C双键含量高的大分子单体（MAA-PtBMA）,其相对分子质量可控制在5400-12000g/mol的范围内,分子量分布≤1.20。以偶氮二异丁腈为自由基引发剂,在乙醇中使MAA-PtBMA大分子单体与苯乙烯（St）进行分散共聚,制得了甲基丙烯酸叔丁酯接枝聚苯乙烯（PtBMA-g-PSt）微米级共聚微球,该微球具有核壳结构。     

紧束缚模型方法及其在DNA分子中的应用

近年来,紧束缚模型方法被广泛应用于计算生物大分子体系.本文从第一性原理出发,根据紧束缚近似的思想,推导出生物大分子体系中的单电子运动方程.在此基础上给出了紧束缚模型方法中所涉及参数(在位能和迁移积分)的计算公式,在理论上完善了紧束缚模型方法.我们将所提出的参数化方法应用于理想B型DNA分子,给出了各种序列组合下的在位能和迁移积分.此外,我们还计算了周期性DNA分子poly(A)-poly(T)和poly(G)-poly(C)中空穴在位能和迁移积分随格点间距离的变化,为改进现有的SSH极化子模型提供了新的思路,有助于DNA中电荷输运的极化子机理的研究.     

阴离子型含氟两亲接枝共聚物的合成及其胶束化行为研究

以聚乙二醇甲醚甲基丙烯酸酯(MPEGMA)为大分子单体,甲基丙烯酸六氟丁酯(HFMA)、对苯乙烯磺酸钠(NaSS)为共聚单体,采用大分子单体接枝共聚法,制备了一种阴离子型含氟两亲接枝共聚物P( HFMA-co-NaSS) -g-PEG.利用FTIR、1H-NMR和19F-NMR对共聚物的分子结构进行了表征.表面张力法测...     

双链特异性核酸酶的生物学和医学应用

双链特异性核酸酶DSN是一种能高选择性地识别并酶切完全匹配的DNA双链或者DNA-RNA杂交双链中的DNA,而对单链DNA和RNA几乎没有作用的核酸酶.DSN酶的上述特点使其在生物和医学等领域广泛应用,主要包括全长cDNA文库的均一化、单核苷酸多态性(SNP)检测和高通量测序等.近年来,DSN酶在microRNAs(miRNAs)的检测领域得以长足发展和应用.miRNAs是一组内源性、非编码短序列RNAs,在生理和病理过程中具有重要作用,但由于其序列短、丰度低等特点, miRNAs的检测一直是临床难题.新近研究主要基于DSN酶信号放大的特点,相继建立了一系列生物传感技术,通过采用不同检测原理如比色法、荧光法、电化学法等实现痕量miRNAs检测.本文就DSN酶在miRNAs检测、SNP检测、全长cDNA文库均一化及高通量测序等方面的生物学应用进行了综述.     

甲壳素/壳聚糖接枝共聚反应

综述了近年来甲壳素/壳聚糖接枝共聚的研究进展。以不同单体分类,分别综述了壳聚糖与小分子乙烯基单体、大分子聚乙二醇单体、聚乳酸单体、环糊精、树状大分子接枝的研究,并介绍了新的接枝技术——生物催化接枝共聚,以及接枝壳聚糖衍生物的应用。     

新型β-双链桥连双卟啉的合成及光敏活性

设计合成了一种β-双链桥连双卟啉及其Cu(Ⅱ),Ni(Ⅱ),Zn(Ⅱ)配合物,通过1HNMR,MS,IR,UV和元素分析进行了表征.以1,3-二苯基异苯并呋喃(DPBF)为猝灭剂测试了β-双链双卟啉产生单线态氧的能力;通过DNA凝胶电泳比较了其对pBR322质粒DNA的光敏切割效果;采用紫外-可见光谱滴定法研究了其与小牛胸腺DNA的相互作用.实验结果表明,光敏剂β-双链双卟啉具有较强的产生单线态氧能力,β-双链桥连使双卟啉对pBR322质粒DNA具有较好的光敏切割效果,与DNA有较强的结合能力.     

γ-环糊精包结折叠双链PEG聚准轮烷材料的性能研究

基于环糊精(CD)的单链与双链包结聚准轮烷(PPR)和聚轮烷(PR)的研究引起人们的极大兴趣.大量证据表明聚乙二醇(PEG)链段能够以折叠双链或双链并行的方式穿过γ-CD空腔.利用双2-溴异丁酰为端基的PEG与γ-CD进行自组装能形成双链包结聚准轮烷,并可作为大分子引发剂引发甲基丙烯酸正丁酯(BMA)发生本体原子转移自由基聚合(ATRP),聚合产物与其作为大分子引发剂的聚准轮烷都为PEG折叠双链包结结构的聚准轮烷.聚合产物能够在三氯甲烷中流延成膜.由于加入的γ-CD以管道结晶形式存在,与PBMA-PEG-PBMA三嵌段共聚物相比,该材料表现出较高的力学强度,但延伸性明显降低.与PBMA均聚物相比,其静态接触角有显著降低,却比PBMA-PEG-PBMA有少许增加.如将其溶于二氯甲烷中,可通过电纺丝加工成结构均匀的无纺布纤维,纤维形貌受到溶液浓度的影响.     

钯铂抗癌配合物初步筛选的荧光法研究

用溴化乙锭/DNA体系荧光筛选法,对以二齿胺或氨为第一配体、硝酸根或生物大分子(小牛血清白蛋白或葡聚糖)为第二配体合成的14种钯、铂配合物进行了研究。确定了配合物的抗癌活性及其DNA的结合常数K_M;发现低浓度下硝酸根配体配合物以插入方式与DNA结合,而大分子配体配合物与DNA作用并非单一的插入方式。本法操作简便、受环境影响小,且对抗癌配合物筛选结果与其它体外法基本接近。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.