树枝状偶氮液晶高分子(PAMAM-MMAZO)的合成及表征

树枝状偶氮液晶高分子(PAMAM-MMAZO)的合成及表征;树枝状聚酰胺-胺;树枝状偶氮液晶;表面修饰;液晶性     

不同引发核树枝状大分子的合成

含不同分支官能团树枝状大分子的合成是目前研究的一个热点。文献报道的有两方向引发核、三方向引发核、四方向引发核、六方向引发核等结构新颖的树枝状分子。本文综述了不同引发核及其衍生物在树枝状大分子合成中的应用。     

树枝状高聚物的合成概况

树枝状高聚物可通过收敛法与发散法等方法合成。本文以树枝状高聚物的组成结构分类综述了最近树枝状高聚物的合成情况     

新型树枝状分子复合载体的合成及其对脂肪酶的固定化

新型树枝状分子复合载体的合成及其对脂肪酶的固定化;猪胰;树枝状分子二氧化硅复合载体     

溶液中柔性树枝状高分子的分子动力学模拟

采用分子动力学模拟方法研究了柔性树枝状高分子在无热溶剂中的静态和动态行为. 模拟结果表明: 在分子尺寸和回转半径Rg满足标度律Rg~N1/5(G+1)2/5P2/5(其中N为树枝状分子的聚合度, G为代数, P为链节长度, g为子代代数)时; 随着代数的增加, 树枝状分子和硬球的静态结构因子相似, 表明其内部结构发生了由“类星形”向“近球形”转化. 随着树枝状分子代数和链节长度的增加, 出现了“单元”(Monomer)密度几乎不变的区域. 树枝状分子的回折能力随着链节长度的增加而增强, 随着代数的增加而减弱. 树枝状分子各子代的运动能力不同, 与内层子代相比, 外层子代在短时间内扩散较慢, 但其松弛较快. 相对于Rouse指数, 树枝状分子“单元”运动的标度更接近Zimm指数.     

树枝状共轭聚合物研究

本文介绍了树枝状共轭聚合物的最新发展,包括全共轭、部分共轭树枝状聚合物及树枝化共轭聚合物的特点及其在电致发光、电极、传感器以及光探测等领域的功能化应用;详细讨论了包括代数、支化单元、端基、核、金属离子的络合等结构因素以及溶剂和浓度等工艺因素对电荷传输的影响;并进一步提出该领域研究前景及有待于解决的问题.     

树枝状共轭聚合物研究

本文介绍了树枝状共轭聚合物的最新发展,包括全共轭、部分共轭树枝状聚合物及树枝化共轭聚合物的特点及其在电致发光、电极、传感器以及光探测等领域的功能化应用;详细讨论了包括代数、支化单元、端基、核、金属离子的络合等结构因素以及溶剂和浓度等工艺因素对电荷传输的影响;并进一步提出该领域研究前景及有待于解决的问题。     

含硅的树枝状大分子的研究进展

树枝状大分子是一类具有规则的、高度支化的三维结构的高分子 ,含硅的树枝状大分子是以硅原子作为两代之间的支化点的树枝状大分子。本文主要综述了硅氧烷型、碳硅烷型、硅烷型树枝状大分子的合成方法及含硅的树状金属络合物的研究进展。     

多肽树枝状大分子合成的研究进展

多肽树枝状大分子具有不同于链状多肽和其它树枝状大分子的物理化学性质,在化学、生物、医学等领域中有广泛应用。本文综述了近年来所报道的多肽树枝状大分子的合成进展。     

外围由小分子修饰的树枝状聚酰胺的合成及其荧光性能研究

合成了1－5代外围由小分子荧光体修饰的树枝状聚酰胺，通过红外，紫外，核磁等表征了其结构，并对其荧光性能进行了研究，修饰后的固体产物的荧光较修饰前粘稠体产物的荧光强得多，树枝状高分子荧光受组分比，代数，溶液浓度，溶剂等因素的影响，有机硅对树状高分子的端氨基与3，5二羟基苯甲酸按1／1摩尔比反应时，其产物荧光最强，对于端氨基与3，5－二羟基苯甲酸摩尔比为1／1的不同代树枝状聚酰胺而言，2代产物荧光最强。     

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.     

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.     

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.     

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.