琼枝多糖的~(13)C-NMR结构分析

对琼枝多糖进行~(13)C—NMR结构分析。结果表现琼枝多糖是一种混杂卡拉胶,其主要成分是部分脱硫K—卡拉胶,次要成分是部分脱硫μ-卡拉胶,此外,还有少量甲基半乳糖和半乳糖丙酮酸缩醛存在。     

卡拉胶电荷量对牛血清蛋白/卡拉胶复合物包载姜黄素的增强作用的影响

本文研究了带有不同负电荷量的κ-卡拉胶和λ-卡拉胶对牛血清蛋白/卡拉胶复合物包载姜黄素的增强作用。卡拉胶通过与牛血清蛋白之间的静电吸引作用,可以生成高稳定性的牛血清蛋白/卡拉胶复合物。相比纯牛血清蛋白,牛血清蛋白/卡拉胶复合物能够显著提高姜黄素的溶解度和稳定性。姜黄素的紫外和荧光光谱表明姜黄素主要是通过疏水作用缔合于牛血清蛋白的疏水微区。卡拉胶与牛血清蛋白的静电吸引作用能够稳定牛血清蛋白的折叠结构,从而使牛血清蛋白为姜黄素提供更加疏水的缔合微环境。相比纯牛血清蛋白和牛血清蛋白/κ-卡拉胶复合物,带有更高负电荷的λ-卡拉胶与牛血清蛋白生成的牛血清蛋白/λ-卡拉胶复合物与姜黄素有更大的缔合常数和pKa1。     

麒麟菜多糖的研究Ⅲ碱金属离子对琼枝多糖溶液性质及凝胶结构的影响

<正> 前言我们曾研究了琼枝多糖的组成、结构以及溶液在不同温度下的流变性质本文就碱金属离子对琼枝多糖溶液粘度、胶凝温度及凝胶结构的影响进行研究。卡拉胶(Carrageenan)水溶液的性质和凝胶形成机理及结构的研究已有一些报导,包括了碱金属离子对卡拉胶溶液性质的影响及钾离子对K-卡拉胶的“凝集”作用。从这些报导中可以肯定,碱金属离子对卡拉胶溶液的性质及凝胶的形成有十分明     

魔芋精粉与黄原胶协同相互作用及其凝胶化的研究

魔芋精粉与黄原胶均为非凝胶多糖,但二者共混可以得到凝胶．当魔芋精粉与黄原胶的共混比例为３０／７０、多糖总浓度为１％,可达到协同相互作用的最大值．同时也讨论了制备温度（Ｔｐ）和体系盐离子浓度对凝胶化的影响,并从其ＦＴＩＲ谱图上分析了这两种多糖分子间相互作用的机理．     

糖胶树叶挥发油化学成分研究

采用水蒸气蒸馏法提取糖胶树叶的挥发油.运用气质谱联用(GC-MS)技术研究海南糖胶树叶的挥发油化学成分.并采用峰面积归一化法确定各成分的相对质量分数.结果共鉴定出36种成分,占总离子流出峰面积的94.83%.糖胶树叶挥发油主要有α-蒎烯(16.62%),2-丙烯酸丁酯(15.86%)和大根香叶烯D(13.37%).本研究可为糖胶树的进一步研究开发和利用提供基础研究数据.     

193nm化学放大光刻胶研究进展

193 nm光刻胶主要有化学/非化学放大、分子玻璃和无机-有机杂化等类型。目前,商业化193 nm光刻胶基本为化学放大型,主要成分包括聚合物树脂、光致产酸剂、添加剂(碱性添加剂、溶解抑制剂等)和溶剂等。本文从光刻胶的成分出发介绍193 nm化学放大胶的研究进展,概述目前应用及研究中出现的代表性193 nm化学放大胶,总结其优缺点及未来可能的发展方向。     

κ-卡拉胶寡糖AEC柱前衍生物的LC-ESI-MS/MSn分离分析

以κ-卡拉胶为原料, 经盐酸水解得到一系列寡糖混合物. 以3-氨基-9-乙基咔唑(3-amino-9-ethylcarbazole, AEC)为衍生化试剂, 对酸解得到的κ-卡拉胶寡糖进行柱前衍生, 采用反相C₁₈色谱柱(250 mm×4.6 mm, 5 μm), 乙腈和乙酸铵水溶液(pH 4.5)为流动相, 梯度洗脱, 在254 nm波长处检测, 建立了κ-卡拉胶寡糖衍生物的高效液相色谱(HPLC)分离以及液相色谱-电喷雾质谱联用(LC-ESI-MS)分离分析的方法, 并对AEC衍生后的κ-卡拉胶寡糖进行多级质谱裂解(MSⁿ), 进一步获得了κ-卡拉胶寡糖的结构信息. 该方法对κ-卡拉胶寡糖的结构分析、构效关系等方面的研究有参考价值.     

中性条件下魔芋胶微球的制备及其药物释放

以span-80为表面活性剂,石蜡为油相(O),魔芋胶溶液为水相(W),采用W/O乳化法,在中性条件下添加硫酸钠制备魔芋胶微球。研究表明:在85℃反应5 h,当油水体积比(O/W)处于6~10时,微球粒径为0.120~0.330 mm;增加O/W比,可减小微球粒径;增加反应物浓度,可减少微球的溶胀度。对包裹牛血清蛋白(BSA)的微球进行体外释放表明,增加微球粒径、反应物浓度可以减缓药物释放速率。     

基于脱乙酰基魔芋葡甘聚糖固定酶的H2O2生物传感器

对魔芋葡甘聚糖进行了脱乙酰基改性处理,并用红外光谱表征了其脱乙酰基前后的结构变化.探讨了脱乙酰基魔芋葡甘聚糖溶胶-凝胶的制备条件对其成膜性能及酶固定化的影响.将脱乙酰基魔芋葡甘聚糖用于辣根过氧化物酶的固定,制备出了H2O2生物传感器.传感器在优化的工作条件下线性范围为1.0×10-6 ～6.0×10-4 mol/L,检出限为8×10-7 mol/L,稳定性良好.实验表明脱乙酰基魔芋葡甘聚糖是一种适用于生物传感器领域酶固定化的优良材料.     

系列ι-卡拉胶寡糖制备及其电喷雾串联质谱序列分析

以ι-卡拉胶为原料,在稀酸条件下进行酸水解得到其寡糖混合物,采用低压凝胶渗透色谱(LPGPC)进行分离纯化,获得了10个寡糖单体.在利用聚丙烯酰胺凝胶电泳(PAGE)和高效薄层层析(HPTLC)对其纯度进行分析的基础上,通过红外光谱(IR)、核磁共振波谱(NMR)和电喷雾离子化质谱(ESI-MS)对其结构进行表征,并用电喷雾碰撞诱导串联质谱(ESI-CID-MS/MS)对其序列进行分析.结果表明,它们分别是还原端为2-硫酸-3,6-内醚半乳糖(A2S)和非还原端为4-硫酸-半乳糖(G4S)的ι-卡拉胶二至二十糖.这些酸法水解制备的寡糖结构新颖,不同于ι-卡拉胶酶法制备的新ι-卡拉胶寡糖.这不仅丰富了海洋寡糖库数据,也为进一步运用糖生物芯片技术探索其与蛋白之间的相互作用提供了物质基础.     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.