表面活性剂在水溶液中性质的质子核磁共振研究

综述了质子核磁共振的几种方法在表面活性剂水溶液研究中的应用.自从上世纪六十年代以来的许多研究表明核磁共振的各种技术是研究表面活性剂溶液的有效手段.它可以提供表面活性剂在水溶液中的cmc、胶束的结构、尺寸、水化、加溶性质和位置，不同表面活性剂胶束之间的相互作用，以及胶束与生物分子和高聚物的相互作用.化学位移已经成为惯常方法，弛豫测量提供动态信息，自扩散系数测量是研究胶束尺寸的很好手段.近来由于核磁共振技术的不断发展，用于研究生物大分子的2D NOESY和HOESY也逐渐应用到研究表面活性剂聚集结构中.由此可以得到有关表面活性剂在水溶液中行为的分子水平信息，是其它谱学方法所不能及的.     

DMA水溶液的1H NMR研究

测量了N，N-二甲基乙酰胺(DMA)水溶液体系不同温度下全浓度范围的^1H NMR数据，对体系中的缔合情况进行了讨论。应用化学缔合模型求得了各缔合平衡常数K和缔合平衡的△H，结合N，N-二甲基甲酰胺(DMF)和N-甲基乙酰胺(NMA)水溶液的研究结果，发现酰胺自身结构和酰胺浓度是影响酰胺水溶液性质的主要因素。     

1H NMR Analysis of Heteroassociation of Caffeine with Mitoxanthrone in Aqueous Solution

Heteroassociation of caffeine (CAF) with the antibiotic mitoxanthrone (novatrone, NOV) in aqueous solution was studied by one-dimensional (1D) and two-dimensional (2D) ¹H NMR spectroscopy (500 MHz). The concentration and temperature dependences of the proton chemical shifts of the molecules in aqueous solution have been measured. The equilibrium constants of heteroassociation between CAF and NOV and the limiting proton chemical shifts of the aromatic ligands of the associates have been determined. The most plausible structure of the 1:1 CAF–NOV heterocomplex in aqueous solution was inferred from the calculated values of the induced proton chemical shifts and quantum-mechanical screening curves for CAF and NOV. The thermodynamic parameters of the formation of the CAF–NOV heterocomplex have been calculated. The relatively high heteroassociation constant (K = 256 ± 31 M^–1, T = 318 K), the positive value of entropy for heteroassociation [ S = 15.3 ± 4.0 J/(moleK)], and the structural features of the chromophore of the novatrone molecule indicate that hydrophobic interactions play a significant role in stabilization of the CAF–NOV heterocomplex.     

1H NMR Study of Heteroassociation of Daunomycin and Propidium Iodide in Aqueous Solution

Heteroassociation of an anthracycline antibiotic Daunomycin (DAU) and phenanthridine dye Propidium iodide (PI) in aqueous solution was studied by ¹H NMR spectroscopy. The complex PI-DAU is stabilized mainly by dispersion van der Waals interactions and hydrogen bond between the 3(8)-amino group of the dye and 9-acetyl group of DAU. This conclusion follows from comparison of parameters of DAU-PI heteroassociation and complex formation of DAU with aromatic dyes, Proflavine and Ethidium bromide, under the same conditions.     

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.     

Structural and Thermodynamic Analysis of Self-Association of Phenanthridine Dyes in Aqueous Solution by 1H NMR Spectroscopy

Self-association of phenanthridine dyes (ethidium monoazide EMB and ethidium diazide EDC) in aqueous solution was studied by one- and two-dimensional ¹H NMR (500 MHz). 2D-TOCSY and 2D-ROESY experiments were used for signal assignment of the dye protons. The concentration and temperature dependences of the chemical shifts of the nonexchangeable protons of EMB and EDC in aqueous solution have been measured. The experimental results were analyzed based on the infinitely dimensional noncooperative and cooperative models of self-association of molecules. The cooperativity parameter, the equilibrium constants, and the enthalpies and entropies of self-association of the dyes were calculated along with the limiting chemical shifts of EMB and EDC protons in the associates. The cooperativity parameter 1 indicates that association of phenanthridine dye molecules in aqueous solution is not a cooperative process. The presence of azido groups in the phenanthridine chromophore diminishes the equilibrium constant and the enthalpy of formation of dye aggregates in aqueous solution. The most plausible structures of EMB and EDC dimers in aqueous solution were derived from the induced proton chemical shifts of the dyes. In the dimer complexes of EMB and EDC, the distances between the planes of the aromatic chromophores are longer than those in the dimer of ethidium bromide due to electrostatic repulsion of the dipole azido groups in the phenanthridine chromophores of the dyes.     

A Facile Diagnostic 1H NMR Method for Syn and anti Hydroxy Systems

In diastereomeric hydroxyl-containing systems, the relative ¹H-NMR chemical shift of the carbamate NH of the in situ generated trichloroacetylisocyanate derivatives appear to be diagnostic for the syn and anti stereochemistry.     

The Isomeric Composition of 6-Deoxy-D-XYLO-Hexos-5-Ulose in Aqueous Solution as Determined by 1H and 13C NMR

Abstract

Acid hydrolysis of 6-deoxy-1,2-O-isop ropylidene-α-d-xylo-hexo-furanos-5-ulose (4) yielded gummy 6-deoxy-d-xylo-hexos-5-ulose (1) as an isomeric mixture of two furanose forms, 6-deoxy-α-d-xylo-hexo-furanos-5-ulose and 6-deoxy-β-d-xylo-hexofuranos-5-ulose, and a pyranose structure 1R, 5R-6-deoxy-d-xylo-hexopyranos-5-ulose. The combined percentage (64%) of the furanoses represents an unusually large amount of free carbonyl form for a sugar when compared to simple hexoses and 2-hexuloses. Isomeric structures were determined in deuterium oxide solution by ¹H and ¹³C NMR.     

Thermodynamic Analysis of Self-association of Actinocin Bis(2-dimethylaminoethyl)amide in Aqueous Solution by 1H NMR Spectroscopy

Self-association of a synthetic antibiotic, actinocin bis(2-dimethylaminoethyl)amide (ActII), in aqueous solution was studied by one- and two-dimensional ¹H NMR spectroscopy (500 MHz).     

Hydroxy group substituent effects on 1H NMR chemical shifts in the structural elucidation of spirostanes

¹H NMR chemical shifts in spirostanes have been determined by spin-decoupling difference spectroscopy. Substituent effects of 7β-OH on 15-methylene proton shifts, 1β-OH on 11α- and 2α-proton shifts and 6α-OH on 4α-proton shifts have been determined and used in the structural assignment of spirostanes.     

双碳醇水溶液的1H NMR实验与理论分析

In this study, ¹H nuclear magnetic resonance (NMR) measurements and quantum chemistry (QC) studies of ethanol (ET)-water mixtures and ethylene glycol (EG)-water mixtures are carried out at different temperatures to discuss the interactions between water and the alcohols present in the mixtures. From ¹H NMR spectra, it is observed that the chemical shift of the water proton shows two different trends in the ET-water mixtures and the EG-water mixtures. With increasing water concentration, the water proton chemical shift decreases dramatically for ET-water mixtures, while the chemical shift increases slowly for EG-water mixtures. The alcohol hydroxyl proton resonance peaks of both ET and EG shift to lower field with decreasing water concentration. It is found that the resonance peaks of all alkyl protons shift monotonically to low field with increasing alcohol concentration at different temperatures. The geometry optimization results indicate the formation of H-bonds between the water molecules and the hydroxyl groups of the alcohols alongside the weakening of O-H bonds in the alcohols, which results in an O-H bond length decrease. It is interesting to note that the bond length values computed for C-C, C-H and O-H bond in both ET and EG are larger when calculated at the density functional theory (DFT) (B3LYP) level than when calculated using Hartree-Fock (HF) level of theory with the same polarization function and diffusion function. However, the O-H…O H-bond computed at HF level of theory is stronger than that calculated at DFT level of theory. The theoretical results are in good agreement with the experimental ones. In the calculation of NMR chemical shift, DFT(B3LYP) is better than HF, which implies that for the same method, the larger the basis sets are, the more accurate are the calculated values.     

Simulation of 59Co NMR Chemical Shifts in Aqueous Solution

⁵⁹Co chemical shifts were computed at the GIAO‐B3LYP level for [Co(CN)₆]^3?, [Co(H₂O)₆]³⁺, [Co(NH₃)₆]³⁺, and [Co(CO)₄]^? in water. The aqueous solutions were modeled by Car–Parrinello molecular dynamics (CPMD) simulations, or by propagation on a hybrid quantum‐mechanical/molecular‐mechanical Born–Oppenheimer surface (QM/MM‐BOMD). Mean absolute deviations from experiment obtained with these methods are on the order of 400 and 600 ppm, respectively, over a total δ(⁵⁹Co) range of about 18 000 ppm. The effect of the solvent on δ(⁵⁹Co) is mostly indirect, resulting primarily from substantial metal–ligand bond contractions on going from the gas phase to the bulk. The simulated solvent effects on geometries and δ(⁵⁹Co) values are well reproduced by using a polarizable continuum model (PCM), based on optimization and perturbational evaluation of quantum‐mechanical zero‐point corrections.     

研究塑性有机固体的1H NMR方法

塑性有机固体的＾１Ｈ ＭＡＳ ＮＭＲ谱通常由一高分辨谱与一宽线谱组成，其中高分辨谱分量对应于塑性相，而宽线谱分量对应于刚性相。长延迟回波－ＭＡＳ ＮＭＲ实验可测得塑性相的高分辨谱，ＣＲＡＭＰＳ方法可测得整个固体＾１Ｈ体系的高分辨谱，常温下它往往以刚性相的贡献为主要成分。实验结果表明，结合＾１Ｈ ＭＡＳ、回波－ＭＡＳ与ＣＲＡＭＰＳ等三种固态高分辨＾１Ｈ ＮＭＲ技术可望成为深入研究塑性有机固体中塑性相     

Dendr.PE-PAA在水溶液中自聚集的NMR研究

用1H NMR自扩散系数,核弛豫和二维NOESY谱研究了新合成苄醚树枝体与丙烯酸杂化嵌段共聚物在水溶液中生成胶团的动态行为.体系中苄醚树枝体与丙烯酸杂化嵌段共聚物的各1H核的自旋-晶格弛豫时间（T1）、自旋-自旋弛豫时间（T2）、自扩散系数和二维NOESY中的交叉峰证明苄醚树枝体与丙烯酸杂化嵌段共聚物在水溶液中形成自聚集,且与不同浓度下聚集体有差别.     

Solution 1H NMR confirmation of folding in short o-phenylene ethynylene oligomers

Oligomers based on an o-phenylene ethynylene (oPE) backbone with polar substituents have been synthesized using Sonogashira methods. Folding of these extremely short oligomers was confirmed via 1D and 2D (NOESY) NMR methods. Utilizing electron-rich and electron-poor phenylene building blocks, variations of these oPE oligomers have been synthesized to determine the folded stability of pi-rich vs pi-poor vs pi-rich-pi-poor systems. Slight variations in temperature offer a route, aside from solvent denaturation, to probe the stability of the folded structure. This is the first report of an NMR solution characterization of folding for a PE backbone without hydrogen bonds.     

Cyclodextrins Binding to Paeonol and Two of Its Isomers in Aqueous Solution. Isothermal Titration Calorimetry and 1H NMR Investigations of Molecular Recognition

Interactions between CDs with three substituted phenols, paeonol (Pae), acetovanillone (Ace) and 2-hydroxyl-5-methoxy-acetophone (Hma), which are isomers, have been determined by isothermal titration calorimetry (ITC) and ¹H NMR in aqueous solution at 298.2 K. Both the binding thermodynamics and ¹H NMR spectra show that the interaction between α-cyclodextrin (α-CD) molecule and each guest molecule is extremely weak. The thermodynamic parameters indicate that the binding processes of β-cyclodextrin (β-CD) with the isomers are mainly entropy driven and that β-CD binds with Pae or Ace in 1:1 stoichiometry, whereas with Hma binds in 1:1 and 2:1 stoichiometries. The thermodynamic parameters also suggest that γ-cyclodextrin (γ-CD) binds each isomer in the same 1:1 stoichiometry. The binding processes of Pae and Hma with γ-CD are enthalpy driven whereas Ace with γ-CD is predominantly driven by entropy. The ¹H NMR spectra reveal that the three isomers were trapped into the torus cavity of the β-CD molecule from the narrow side during the binding process. Pae penetrates into the γ-CD cavity from the primary rim of the macrocycle whereas Ace does so from the secondary rim, but Hma appears not interact with the internal cavity of γ-CD at all.     

NMR研究水溶液中L-精氨酸与磷酸腺苷的相互作用及其构象变化

利用核磁共振(NMR)方法,研究了水溶液中L-精氨酸分别与一磷酸腺苷、三磷酸腺苷的相互作用及其构象变化.通过测定L-精氨酸分别与一磷酸腺苷、三磷酸腺苷混合后体系的1H、13C NMR,对混合前后L-精氨酸1H及13C化学位移变化情况进行了分析,发现L-精氨酸与一磷酸腺苷、三磷酸腺苷存在氢键和静电作用,并且这种相互作用会导致L-精氨酸构象产生变化,即由作用之前的伸展型转变为作用后的弯曲型.     

Synthesis,NMR and Conformational Studies of Fucoidan Fragments 1:1 Desulfated 2,3- and 3,4-Branched Trisaccharide Fragments and Constituting Disaccharides

ABSTRACT

Two fucotriosides with vicinal disubstitution α-L-Fuc-(1→2)[α-L-Fuc-(1→3)]α-L-Fuc-OPr (1) and α-L-Fuc-(1→3)[α-L-Fuc-(1→4)]α-L-Fuc-OPr (2), which are related to fragments of natural polysaccharides fucoidans, have been synthesized together with constituent disaccharides 3-5. Spectral and conformational properties of tri- and disaccharides have been investigated by ¹H, ¹³C and NOE NMR spectroscopy.