邻苯二甲酸L—（＋）—2,3—O—亚异丙基苏力糖酯的两种构象式的 …

在晶（固）态下，化合物邻苯二甲酸Ｌ－（＋）－２，３－Ｏ－亚异丙苏力糖酯存在两种不同的构象形式，利用螺旋片段判定规则及ω＾－值，结合Ｘ射线衍线数据及扭转角数据，对这两种构象形式的所有螺旋片段进行了分析，尽管两种构象形式的净值螺旋性相反，但仍然得出总净值螺旋性与旋光方向一致的总论。     

胆甾相液晶螺旋方向的光调控

光响应胆甾相液晶是一类在光刺激下通过改变液晶分子排列调控光学特性的智能“软”光子晶体材料,其分子自组装形成周期性螺旋结构,选择性地反射与自身螺旋方向相同的圆偏振光。近年来,利用光刺激诱导胆甾相液晶在左手螺旋和右手螺旋之间发生螺旋翻转的研究引起了广泛关注。胆甾相液晶的螺旋翻转能够改变反射光的圆偏振特性,有望拓展光子晶体材料在可调节滤光器、防伪与加密技术、圆偏振激光器、三维显示等领域的潜在应用。本综述重点关注光响应胆甾相液晶螺旋翻转的研究进展;总结了调控胆甾相液晶螺旋方向的两种主要策略：(1)直接引入螺旋性可逆转变的光响应手性分子开关,(2)利用光响应手性分子开关和与之螺旋性相反的手性掺杂剂之间的手性竞争;分析了分子空间构型转变对调控螺旋翻转程度的影响;并讨论了不同材料体系面临的挑战以及未来的发展方向。     

S-(-)-2,2′-联二萘酚衍生物的合成及其螺旋结构与旋光性的关系

以S-(-)-2,2’-联二萘酚为手性模板分子,合成出了它的两个七元环衍生物.通过对它们的旋光值、X衍射结构及构象的研究,找出了它们的螺旋结构与旋光性的关系,并对其族光大小进行了比较.此外,首次提出我们建立的螺旋片段判定规则及我们定义的ω值.     

S-(-)-2, 2'-联二萘酚衍生物的合成及其螺旋结构与旋光性的关系

以S-(-)-2,2'-联二萘酚为手性模板分子,合成出了它的两个七元环衍生物。通过对它们的旋光值、X衍射结构及构象的研究,找出了它们的螺旋结构与旋光性的关系,并对其旋光大小进行了比较。此外,首次提出我们建立的螺旋片段判定规则及我们定义的ω值。     

S-(-)-2, 2'-联二萘酚衍生物的合成及其螺旋结构与旋光性的关系

以S-(-)-2,2'-联二萘酚为手性模板分子,合成出了它的两个七元环衍生物。通过对它们的旋光值、X衍射结构及构象的研究,找出了它们的螺旋结构与旋光性的关系,并对其旋光大小进行了比较。此外,首次提出我们建立的螺旋片段判定规则及我们定义的ω值。     

致癌有机化合物分子片段致癌机理的研究

以有机物的分子连接性指数和微扰分子轨道指数作结构、能量参数,从分析致癌有机物分子片段与生物遗传基因DNA链互补碱基对发生共价交联的构效角度出发,首次得出产生碱基移码型或碱基置换型化学致癌的主要过程是化合物分子片段中活性原子与DNA互补碱基对间氢键的共价结合,显示致癌活性的充分必要条件是碱基对G≡C间有两个氢键与致癌分子片段发生特异交联.对100余种已知致癌物的致癌分子片段进行计算分析,成功地获得了有机物分子片段定量结构-致癌活性的估测模式.     

Z_(Aβ3)和Aβ_(16–40)亲和作用的分子机理解析

淀粉样多肽(amyloid-βpeptide,Aβ)聚集是引起阿尔兹海默症(Alzheimer's disease,AD)的主要原因。开发Aβ聚集抑制剂是治疗AD的最有效手段之一。利用噬菌体展示技术筛选出来的Z_(Aβ3)蛋白质能够有效抑制Aβ聚集,但Z_(Aβ3)和Aβ之间的作用区域和关键氨基酸残基尚不清楚。针对此问题,本研究利用分子动力学模拟、MM-PBSA自由能计算和分解方法研究了Z_(Aβ3)-Aβ_(16–40)复合物之间的相互作用机制。结果表明,Z_(Aβ3)的β-股和Aβ_(16–40)之间的亲和作用占主导,而Z_(Aβ3)的α-螺旋贡献很小。利用分子力学-帕松波尔茨曼溶剂可及化表面积方法(MM-PBSA)自由能分解发现Z_(Aβ3)的热点残基为E15、I16、V17、Y18、L19、P20、N21和L22,而Aβ_(16–40)的热点残基为F19、F20、A21、E22、D23、K28、I31、I32、G33、L34、M35、V36、G38和V40。Z_(Aβ3)通过将发夹型Aβ单体包埋在α-螺旋围成的疏水性腔体内来阻碍Aβ聚集。这种结合模式为设计高效的Aβ蛋白质类抑制剂提供了三个基本要素:高亲和性的结合片段(β-股)、附属结构(α-螺旋)和通过二硫键形成的稳定构象。高亲和性结合片段能竞争性地与Aβ单体结合,附属结构α-螺旋可以阻碍其它Aβ单体靠近,而稳定的构象是上述两种要素发挥作用的基础,三者协同作用可以有效地抑制Aβ聚集。     

柴油中正构烷烃的高温气相色谱分析

利用高温气相色谱法对柴油中正构烷烃的碳数分布及含量进行了分析。同时根据所得数据计算出正构烷烃的平均相对分子质量及平均碳原子数。试验表明，气相色谱的最佳测定条件为：柱初温60℃，柱终温330℃，升温速率6℃／min，汽化室温度350℃。分析出吐哈两种柴油中C11～C19的正构烷烃均占分析总量的75％以上，吐哈0^#与-10^#柴油正构烷烃的平均相对分子质量、平均碳原子数分别为214．57、15．18和203．34、14．38。所得数据为设计研究针对吐哈原油有效降凝剂提供了参考数据。     

甲基取代的手性环酯化合物的螺旋结构与旋光性分析

利用螺旋片段判定规则,结合X射线衍射结构图及模型结构,对4个大环酯类化合物及甲基取代产物的螺旋结构与旋光性进行了定量分析,检测结果证明了理论分析的正确性;对旋光值变化规律给予了合理解释.     

順式-、反式-构型和乙烯基含量不同的聚丁二烯的性質

引言聚合过程中,丁二烯分子能以四种方式连接,形成具有完全規整結构的綫状大分子。如果聚合是以1,4加成进行,那么在所形成的聚合鏈中的内双鍵,可能都是順式-构型或反式-构型。如聚合是以丁二烯分子头—尾相接1,2加成进行,可能出现两种不同规整的结构。到底是哪一种規整的結构,这要看在聚合鏈中不对称碳原子是否具有同一的空间构型(仅是d或仅是ι),或是d和ι交替更換。第一种类型的結构叫全同(isotactic),第二类叫间     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.