三种不同分子结构阴离子表面活性剂胶束微结构的NMR研究

用核磁共振测定自旋-晶格、自旋-自旋弛豫时间(t₁,t₂)、自扩散系数(D),用2DNOESY技术对正十四烷基硫酸钠、β-戊基壬烷基硫酸钠和β-戊基壬烷基聚氧乙烯醚(4)硫酸钠三类阴离子表面活性剂水溶液进行了观测,烷烃链各基团的t₂/t₁值给出了这三类分子形成各自胶束的水合层位点信息以及烷烃链在胶束内核中堆积程度的比较,自扩散系数结果表明,β-戊基壬烷基硫酸钠比正十四烷基硫酸钠形成的胶束的水合动力学半径小,但β-戊基壬烷基聚氧乙烯醚(4)硫酸钠形成的胶束水合动力学半径明显大于其它两类表面活性剂胶束,2DNOESY谱图提供了β-戊基壬烷基聚氧乙烯醚(4)硫酸钠分子中聚氧乙烯基键在胶束外层卷曲排列的信息.     

NMR研究溶液中正十四烷基硫酸钠/正十四烷基聚氧乙烯醚(3)表面活性剂之间的相互作用

采用¹HNMR弛豫、自扩散系数和二维相敏(2DNOESY)实验研究了正十四烷基硫酸钠[n-CH₃(CH₂)₁₃OSO₃Na(STS)]和正十四烷基聚氧乙烯醚(3)[n-CH₃(CH₂)₁₃O(C₂H₄O)₃H(C₁₄E₃)]在溶液中的自聚集以及二者混合后的相互作用.结果表明,STS与C₁₄E₃混合后存在相互作用,并形成混合胶束;弛豫实验表明,混合胶束中STS疏水链质子运动更加受阻,C₁₄E₃的α-(4″)和β-CH₂(3″)处链堆积紧密.C₁₄E₃的亲水端(CH₂CH₂0)₃链卷曲紧贴在疏水壳表面外链堆积较紧密处.自扩散系数测量表明,混合胶束比单一阴离子表面活性剂形成的胶束大.单一非离子型胶束和混合胶束的亲水端(CH₂CH₂0)₃(5″)链构成相应较软和松散的外壳.单一C₁₄E₃在极性溶剂氯仿溶液中,质子运动比在水中自由度大,但2DNOESY谱中出现了少量分子间的交叉峰,也可能形成了一些小的聚集体.     

空气/水界面2,5-二丙基-4-十一烷基苯磺酸钠的表面动态扩张流变性质

利用悬挂滴方法研究了2,5-二丙基-4-十一烷基苯磺酸钠(3-11-3)在空气/水界面上的动态扩张粘弹性质, 考察了时间、表面压、工作频率及3-11-3的浓度对扩张模量和相角的影响. 研究结果表明, 低表面压条件下, 表面膜以弹性为主, 分子在表面上的状态决定膜性质；高表面压条件下, 分子在体相和表面间的交换过程决定膜性质, 表面膜以粘性为主.     

n-十二烷基-β-D-麦芽糖苷与十二烷基三甲基氯化铵混合胶束的1H NMR研究

利用NMR技术的自扩散、自旋-自旋弛豫时间(T2)和自旋-晶格弛豫时间(T1)以及二维NOESY谱, 研究了n-十二烷基-β-D-麦芽糖苷(DM)与十二烷基三甲基氯化铵(DTAC)的二元混合体系中混合胶束的形成、大小变化、排列方式、复配比例和相互作用点等. NMR的自扩散系数表明了混合胶束的大小主要取决于DM分子, T2/T1显示混合胶束堆积的较紧密, 两分子的疏水链是以肩并肩的方式位于胶束核中, 2D NOESY 谱表明DTAC分子中与极头相连的亚甲基邻近DM分子中倒数第二个糖环, 产生分子间相互作用, 其相互作用和分子间距的大小随DM/DTAC比例的不同而变化, DM/DTAC在1∶4和1∶8之间是较好的复配比例范围, 并确定混合前后出现的变化T2值是混合胶束中产生相互作用的证椐.     

meso和dl 2,3-二氰基-2,3-二(p-取代苯基)丁二酸二乙酯的~1H NMR研究

测定了meso和dl 2,3-二氰基-2,3-二(p-X苯基)丁二酸二乙酯(X=OCH_3,CH_3,H,Cl,NO_2)的~1H NMR谱及X为CH_3相应二乙酯的~1H Noesy谱。在meso和dl异构体中,苯环m-~1H的化学位移与p-X的Hammett基团常数σ呈线性关系,c~1H的化学位移仅受分子构型的影响,;△δdl-meso为负值,乙氧基中CH_2和CH_3的质子化学位移也只受分子构型的影响,△δdl-meso均为正值。     

复杂缔合体系NMA-H2O的1H NMR研究

N-甲基乙酰胺(NMA)是最简单的肽键模型分子,广泛地被用来研究氢键相互作用.采用外标法测量了不同温度下NMA-H₂O缔合体系的¹H NMR数据,通过磁化率校正得到了混合物的准确化学位移数据.然后用量子化学计算的结果确定体系的缔合形式,运用化学缔合理论建立模型,对模型进行降维,减少模型参数;再采用最小二乘法,联合遗传算法(GA)和Levenberg-Marquardt算法对模型参数进行全局寻优,求解得到了缔合平衡常数和缔合平衡的ΔH和ΔS.此外,还采用密度泛函理论(DFT)计算了NMA-H₂O的几种主要缔合形式在298 K的ΔH,计算结果与化学缔合模型得到的结果和文献吻合较好.     

NMR对苯并噁嗪类化合物结构的研究

利用'H、'13CNMR谱及HMBC、HMQC二维谱对10种苯并噁嗪类化合物的结构进行了研究,初步得出了它们的NMR谱特征,分析了化学位移的影响因素。     

1,2,4-三嗪类化合物的研究(ⅩⅩ)——利用波谱分析确定3-甲硫基-5-羟基-1,2,4-三嗪的取代苯磺酰化反应及其产物的结构

为寻找有效的抗肿瘤药物,作者对1,2,4-三嗪类化合物(6-氮杂尿嘧啶)的化学性质进行了研究,发现3-甲硫基-5-羟基-1,2,4-三嗪(1)在无水吡啶中与对甲苯磺酰氯发生不正常的对甲苯磺酰化反应,生成N-[6-(3-甲硫基-5-负氧基)-1,2,4-三嗪基]吡啶内鎓盐以及对甲苯磺酸对甲苯硫酚酯。为了研究其反应机理,把溶剂改为等摩尔NaOH的CH_3COCH_3-H_2O溶液,重复文献的实验。反应产物分离提纯后,确定其结构为3-甲硫基-4-对甲苯磺酰基-5-氧代-6-羟基-1,4,5,6-四氢-1,2,4-三嗪(2a)。此反应特点是:在1,2,4-三嗪环的4-氮上     

封管样品的1H MAS谱——活性炭吸附H2S及醇类的NMR研究

A mag1c angle spinning system for sealed samples has been achieved with a speed from 1.5 to 4.2 kHz. Using this system, high-resolution ~1H spectra are obtained for H_2S and alcohols adsorbed on charcoal in sealed ampoules. For high coverage of alcohols, the spectral lines are resolved very well, but for low coverage, the spectral lines cannot be separated completely. The details are discussed and the solution is anticipated.     

Si-VPI-5分子筛的多核固体NMR研究

磷酸铝类分子筛是近年来继Y型和ZSM七分子筛之后的第三代合成分子筛材料，其骨架由A10。和P0。四面体均匀交替地组成问．由于带负电行的A10。和带正电荷的PO。四面体数目相等，整个骨架呈电中性，所以这类分子筛本身无离子交换能力和催化活性．当用硅或某些金属离子（如Mg、Fe、Co、Zn等）对磷酸铝分子筛进行同晶取代，就会在骨架上造成电行不平衡，从而使这类分子筛具有一定的离子交换能力和酸性【习．因而对硅或金属离子在磷酸错类分子筛中取代机理的研究一直是人们感兴趣的问题问．Vpl－5是最近才合成出来的具有18圆环一维孔结构的…     

Microstructures of 2,5-dialkyl benzene sulfonate micelles studied using H NMR

Micellization of a series of newly synthesized dialkyl benzene sulfonates was studied using proton chemical shift changes, spin-lattice and spin-spin relaxation NMR spectroscopy, and two-dimensional nuclear Overhauser enhancement spectroscopy (2D NOESY). The o-substituted chains are normal alkyl chains with varying lengths, and the m-substituted ones are branched alkyl chains. The results showed that the longer the o-substituted normal alkyl chain, the more the methylene groups participated in the formation of the rigid surface layers of the hydrophobic micellar cores. Consequently, the larger was the area per molecule adsorbed on the interface between oil and water at saturation. The branched m-substituted alkyl chains of the dialkyl benzene sulfonates were less tightly packed than the o-substituted normal alkyl chains in the hydrophobic micellar cores. The shorter the m-substituted branched alkyl chains, the looser they were packed in the hydrophobic micellar cores. The relative arrangement of the surfactant molecules in the micelles was elucidated.     

1H and 13C NMR data of benzylsulfonic acids-model compounds for lignosulfonate

Although there has been a major progress in the analysis of native lignin using NMR in the recent years, not much attention has been paid to lignosulfonates. Lignosulfonates are more difficult to analyse because of solubility issues and a more complex structure owing to chemical modification during the pulping process. A large database of NMR data is available for the building blocks of native lignin, but no data are available for the corresponding sulfonated compounds. We have prepared 15 monomeric and seven dimeric sulfonated model compounds characterised by NMR. These include models for end groups, as well as beta-beta, beta-5, 5-5 and beta-O-5 linkages in lignosulfonates, and will be important for further structural investigation on lignosulfonate.     

A Study of Dynamic Interfacial Properties as Related to Foaming Properties of Sodium 2,5-dialkyl Benzene Sulfonates

In this article, foaming properties and dynamic interfacial properties of a series of sodium 2,5-dialkyl benzene sulfonates in aqueous solutions were carried out to elucidate the relationship between foaming properties and dynamic interfacial properties. The properties of foams generated from bubbling air through different surfactant solutions were measured using a modified Bikerman device. The dynamic surface tension and surface dilational elasticity were obtained from an image analysis technique based on the oscillating bubble method. The surfactants molecular adsorption at the air/water interface was introduced with Rosen empirical equation and the rate of adsorption was determined from measurements of the dynamic surface tension. The surfactant with the longest alkyl chain shows the lowest dynamic surface activity, which lead to the lowest foam volume. The short ortho straight alkyl chain has little effect on the arrangement of molecules at the interface and the foam stability changes a little with the changing of the ortho alkyl chain length. The foam stability is correlated with both the higher surface dilational elasticity and the larger surface monolayer strength.     

Assignment of the 1H and 13C NMR signals of some hydroxyphenylcoumarins

The complete 1H and 13C NMR assignments of six hydroxyphenylcoumarins have been made using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments.     

Assignment of the 1H and 13C NMR signals of some benzofurocoumarins

The complete 1H and 13C NMR assignment of four 6,7-benzo-fused furocoumarins (1-4) and three 3,4-benzo-fused furocoumarins (5-7) has been performed using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments.     

Detailed assignments of 1H and 13C NMR spectral data of 14 cyclopentane derivatives

Detailed assignments of ¹H and ¹³C NMR spectral data for 14 cyclopentane derivatives are reported. The assignments are based on 1D ¹H and ¹³C NMR and on 2D shift‐correlated [¹H, ¹³C‐HMQC], J‐resolved and NOEDIF experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

季铵盐型双子表面活性剂C14-s-C14·2Br的聚集行为

用1H NMR弛豫、2D NOESY研究了双子表面活性剂14-s-14胶束在重水溶液中的聚集行为. 1H NMR自旋-晶格、自旋-自旋弛豫实验表明, 联结基团质子及其邻近的亚甲基质子的运动受到严重限制, 表明这些质子形成胶束疏水核的壳层；而远离极性头的疏水质子的运动则相对自由, 说明其位于胶束的内部. 14-s-14系列(s=2, 3, 4)的弛豫实验结果还表明, 联结基团越短, 分子的碳氢链在疏水核中的排列越紧密. 与14-4-14的对应单链表面活性剂TTAB相比, 它们的分子运动更受限制. 14-4-14的2D NOESY 谱给出了与16-4-16类似的交叉峰信息, 这表明14-4-14同16-4-16一样, 形成了表面不平滑的球形胶束. 因此, 烷烃链的长短对胶束中分子的排列方式没有影响.     

1H and 13C NMR assignments of abietane diterpenes from Aegiphila lhotzkyana

An NMR study of one new and several known abietane diterpenes isolated from the roots of Aegiphila lhotzkyana is described. In addition to 1D NMR, several 2D shift‐correlated NMR pulse sequences (¹H–¹H‐COSY, NOESY, HMQC and HMBC) were used to establish all the structures, and unambiguously perform the ¹H and ¹³C chemical shift assignments of the new natural diterpene and three derivatives, the NMR data for which have not been reported previously. Revision of current data assignment for teuvincenone H is also suggested. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and complete assignment of the 1H and 13C NMR signals of some oxopyrancoumarin and oxofuropyrancoumarin derivatives

The synthesis of four pyranocoumarins starting from phloroglucinol and the complete (1)H and (13)C NMR assignment of seven pyranocoumarins has been performed using 1D and 2D NMR techniques including COSY, HMQC and HMBC experiments.