某些含二维液晶基元的热致液晶高分子的向列态纹影织构

发现某些含二维液晶基元的热致液晶高分子容易产生反向壁织构与含有高强度向错点(|S|大于1)的向列态纹影织构。这类液晶高分子的织构与形态学特点与含一维棒状液晶基元的其他液晶高分子不同。     

刚性侧链型液晶高分子与含二维液晶基元的液晶高分子

提出了“刚性侧链型液晶高分子”与“含二维液晶基元的液晶高分子”两个新概念。     

一系列含T-型二维液晶基元的液晶高分子配体的合成

以４,４′ （α,ω 亚烷基二酰氧）二苯甲酰氯和２,４ 二羟基 ４′ 烷氧基偶氮苯为单体,通过溶液聚合,合成了一系列新的含Ｔ 型二维液晶基元的液晶高分子配体．单体的结构通过元素分析、ＩＲ、１Ｈ ＮＭＲ和ＭＳ等方法确证．高分子配体通过ＧＰＣ、ＤＳＣ、ＴＧ、ＷＡＸＤ和偏光显微镜等方法测试表征,发现所有的高分子配体加热至各自的熔点以上都能形成液晶态,在液晶态可以观察到向列型的丝状织构和纹影织构．它们的熔点（Ｔｍ）和液晶态的清亮点（Ｔｉ）随分子中末端烷氧基增大和柔性间隔段长度增加呈规律性变化．特别值得一提的是,发现末端不含取代基的高分子配体也能产生液晶态,这对该类高分子液晶态生成的机制与液晶态的织构提供了一个新的研究课题［１］．     

手征性侧链液晶高分子取向结构的研究

用偏光显微镜,红外二色性和Ｘ 射线衍射研究了一种手征性侧链液晶高分子的相态织构和弛豫行为．偏光显微镜观察这种侧链液晶高分子冻结取向液晶态薄膜时,可观察到与剪切方向垂直的明暗相间的条带织构．红外二向色性的结果表明,取向态中侧链上的介晶基元倾向于与剪切方向垂直排列．取向和非取向膜的Ｘ射线衍射揭示了该侧链液晶高分子具有反铁电性液晶的两套反相螺旋结构．取向薄膜在液晶态的弛豫行为表明,取向作用能促进侧链高分子近晶相层状结构的生长,而且介晶基元的取向在弛豫过程中能保持下来．     

主链上含有氧化偶氮苯液晶基元的共聚液晶高分子的研究

以4.4′-二羟基氧化偶氮苯和1,10-癸二醇作为含羟基单体,按不同的重量配比,合成了一系列含氧化偶氮苯液晶基元的共聚液晶高分子,改变液晶基元的含量,共聚物相变温度可以调节。     

条带织构装饰技术观察含T─型液晶基元的热致性聚芳酯液晶态的向错

采用条带织构装饰新技术研究了含Ｔ─型液晶基元的热致性聚芳酯液晶态的向错形态．经过培养的液晶样品无需剪切，淬火后便可呈现出围绕向错点取向排列的条带织构，而条带织构长轴的垂直方向正代表了液晶基元的指向矢方向，这样，在普通偏光显微镜下就能直接观察到这些条带织构装饰的强度Ｓ＝±１／２和Ｓ＝±１的向错，并观察到Ｓ＝－３／２的高强度向错和闭环状的反转壁．     

条带织构装饰技术观察含T─型液晶基元的热致性聚芳酯液晶态的向错

采用条带织构装饰新技术研究了含Ｔ─型液晶基元的热致性聚芳酯液晶态的向错形态．经过培养的液晶样品无需剪切，淬火后便可呈现出围绕向错点取向排列的条带织构，而条带织构长轴的垂直方向正代表了液晶基元的指向矢方向，这样，在普通偏光显微镜下就能直接观察到这些条带织构装饰的强度Ｓ＝±１／２和Ｓ＝±１的向错，并观察到Ｓ＝－３／２的高强度向错和闭环状的反转壁．     

含聚乙二醇柔性间隔段的主链型液晶聚酯的合成

分子结构与液晶行为间的关系是液晶性高分子物理问题研究的核心,通常的液晶性高分子中除液晶性基元外还引入一些相对来说很柔顺的链段,称作柔性间隔段．这是因为人们认识到高分子的液晶行为不只决定于液晶性基元的结构,也受到这些基元间以及基元和间隔段间相互作用的影...     

光致变色液晶高分子研究（Ⅲ）──含胆甾介晶基元和偶氮苯光色基元侧链共聚硅氧烷的液晶行为

用热台偏光显微镜、Ｘ射线衍射和ＤＳＣ研究了含胆甾介晶基元和偶氮苯光色基元侧链共聚硅氧烷（ＰＳＩ）的液晶性．将非介晶基元并入液晶均聚物，所得共聚物的液晶态类型不变，仍显示近晶型织构，在ＰＳＩ共聚物中，保持液晶性的含介晶基元单体的最低极限组成为６０ｍｏｌ％．在液晶性存在的范围内，共聚物的清亮点由１３０℃升至１７０℃，液晶共聚物的热稳定性随非介晶组分含量的增加而增强．     

丁酸壳聚糖液晶的织构研究

用偏光显微镜研究了一种新的液晶高分子－丁酸壳聚糖液晶的织构。丁酸壳聚糖能溶于十多种溶剂中形成胆甾型液晶相。指纹状织构是主要织构，此外还观察到鲜偏振场织构、滴状织构、平面织构和条带织构等，与纤维素衍生物的液晶态结构很相似。     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.