头孢地嗪酸的核磁共振波谱表征

头孢地嗪酸（Cefodizime acid）是头孢地嗪钠（Cefodizime disoclium）的重要前驱体．头孢地嗪钠是第三代半合成头孢菌素,具有广泛的临床应用前景。目的是阐述头孢地嗪酸的核磁共振波谱。方法是应用1DNMR和脉冲梯度场2DNMR技术（gCOSY、gHSQC、gHMBC）对头孢地嗪酸（Cefodizimeacid）进行了检测。对头孢地嗪酸的1H—NMR、13C—NMR信号进行了全归属．以及对1H—NMR谱偶合裂分,偶合常数及1H—NMR．13C—NMR谱中取代基对化学位移的影响进行了分析。解析并归属了头孢地嗪酸分子结构中所有碳氢信号,确证了它的化学结构。     

Two-dimensional H- and C-NMR spectra of some azo dyes containing amino or acetamido groups

The ¹H- and ¹³C-NMR spectra of 12 azo dyes containing amino or acetamido groups have been measured. Two-dimensional H,H-COSY, NOESY, H,C-COSY and COLOC spectra and one-dimensional selective INEPT spectra have been used in the assignment of ¹H and ¹³C chemical shifts. Hydrogen bonding has also been studied in these compounds.     

First-principles studies of diamond polytypes

Using first-principles methods, we have performed a systematic investigation of the cubic, rhombohedral and hexagonal diamond polytypes, both in equilibrium and under hydrostatic pressure. For each of the diamond polytypes (2H, 3C, 4H, 6H, 8H, 9R, 10H-SiC form, 10H-ZnS form, 15R and 21R), the structural, energetic, and electronic properties are investigated. The calculated lattice parameters, mass densities and ground-state energies of the diamond polytypes show clear trends with their hexagonality, while bulk modulus and elastic parameters are rather insensitive to the hexagonality. It is found that there are no phase transitions between these diamond polytypes studied in this work, at a pressure range from 0 to 500 GPa. For the series of diamond polytypes studied, the calculated results indicate that the relationship between ground-state electronic band gap and hexagonality at zero pressure is different from that observed at the hydrostatic pressure of 500 GPa.     

C.I.分散黄71中间体的结构表征

合成了C.I.分散黄71染料中间体并用核磁共振谱和红外光谱表征了它们的结构.用gCOSY、gHSQC和gHMBC二维谱分别确定了其1H和13C NMR谱带的化学位移,同时报道了它们的红外光谱.     

N.M.R. Studies on Aminated Dinitrobenzofuroxan and Dinitrobenzofurazan Derivatives

The ¹³C-n.m.r. chemical shifts of σ-N C-bonded Meisenheimer complexes 3 , 5 and their corresponding aminated dinitrobenzofurazans 4 and dinitrobenzofuroxans 6 were determined. The chemical shifts are discussed as a function of electronic substituent effects. The assignment was performed by means of ¹H ¹³C coupling constants and by comparison with che ¹³C-chemical shifts of appropriate model compounds. The ¹³C-n.m.r. spectra of Meisenheimer tomplexes 3 reveal doubling of signals, indicating a hindered rotation at the N CHO bond.     

NMR studies of water‐borne polyurethanes

A series of water‐borne polyurethanes were prepared by prepolymerization process. Isophorone diisocyanate, polyester diol, and dimethylol propionic acid were used to conduct the reaction. ¹H‐ and ¹³C‐NMR spectra of the raw materials and products thereof were measured with a high‐resolution spectrometer, and their chemical shifts were assigned. ¹H‐ and ¹³C‐NMR spectra of urethane group and urea group were compared. The chemical shifts of side products from the reaction between water and the isocyanate group were also analyzed. Much useful information may be obtained from the NMR analysis of this kind of polyurethanes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 257–260, 2003     

Infrared Reflection Spectroscopy and Effective Medium Modeling of As-Anodized and Oxidized Porous Silicon Carbide

We present a study of the infrared reflectance of porous silicon carbide (PSC) formed by the electrochemical dissolution of silicon carbide substrates of both 6H and 4H polytypes. The reflectance from n-PSC, both as-anodized and passivated, is reported for the first time. The passivation of PSC has been accomplished using a short thermal oxidation. Fourier transform infrared (FTIR) reflectance spectroscopy is employed ex situ after different stages of the thermal oxidation process. The characteristics of the reststrahlen band normally observed in bulk SiC are altered by anodization; further changes in the reflectance spectra occur following oxidation for different periods of time. An effective medium theory model that includes air, SiC and SiO₂ as component materials is shown to characterize the observed changes in the reflectance spectra after different stages of PSC oxidation.     

Microstructural Characterization of SiC–SiC Joint by Raman Spectroscopy

Analysis of the SiC–SiC joint and its brazing mixture has been performed using a Raman spectroscopy microprobe technique. A careful mapping of the sample clearly shows the spatial distribution of the chemical species close to and within the joint. A different distribution of the 4H and 6H α-SiC polytypes, grown during the brazing process, was observed inside the joint. Furthermore, identification of the bands related to the Nowotny phase was also possible.     

The synthesis,characterisation and molecular structure of a new hetarylazoindole dye studied by X‐ray diffraction,spectral analysis and density functional theory calculation

1,2‐Dimethyl‐3‐(5‐methylisoxazol‐3‐yldiazenyl)‐1H‐indole was obtained by coupling 3‐amino‐5‐methylisoxazole with diazotised 1,2‐dimethylindole. It was characterised by proton and carbon nuclear magentic resonance, ultraviolet–visible, infrared and Raman spectra, and the X‐ray single crystal diffraction method. On the theoretical side, the molecular geometry, chemical shifts and the fundamental vibrational frequencies were evaluated using density functional theory. Time‐dependent density functional theory was used to evaluate the electronic excitation spectra. In addition, the scaled quantum mechanical approach was used to study the total energy distributions of the vibrational modes of the molecule. The results showed that the general agreement between experimental and calculated geometric parameters, chemical shifts and λ_max values are good. Excellent agreement was found between the calculated and experimental vibrational frequencies.     

Thermal Expansion and Thermal Expansion Anisotropy of SiC Polytypes

The principal axial coefficients of thermal expansion for the (3C), (4H), and (6H) polytypes of SiC are considered to identify the structural role of the stacking layer sequence as it affects the thermal expansion. A general equation based on the fractions of cubic and hexagonal layer stacking is developed that expresses the principal axial thermal expansion coefficients of all of the SiC polytypes. It is then applied to address the thermal expansion anisotropy of the noncubic SiC structures.     

3，9-二（4-甲基苯）-2，4，8，10-四氧杂螺[5．5]十一烷的NMR研究

对含有手性轴的螺环化合物3,9-二（4-甲基苯）-2,4,8,10-四氧杂螺[5．5]十一烷的一维、二维核磁共振谱（^1HNMR,^13CNMR,DEPT,2D^1H—^1HCOSY,HSQC,HMBC）进行了解析和报道。认真的分析了两个六元杂环上四个亚甲基出现的信号,对其所有的NMR谱信号进行了全归属,为研究含杂原子的手性螺环化合物提供了参考数据。     

Microstructure and texture of polycrystalline 3C–SiC thick films characterized via EBSD

Cubic silicon carbide (3C–SiC) is an excellent protective film on graphite and has been fabricated via laser chemical vapor deposition (LCVD) with an extremely high deposition rate by our research group. To understand comprehensively its growth behavior, the polycrystalline 3C–SiC thick films with the preferred orientation of <111> and <110> were characterized by diverse measurements, especially electron back-scatter diffraction (EBSD). Along the growth direction of the <110>-oriented 3C–SiC, the microstructure changed from equiaxed grains to elongated grains with <111> orientation, and eventually the <110>-oriented columnar grains. The stacking faults in the <110>-oriented 3C–SiC could be marked as <11–20>-oriented 6H–SiC. On the other hand, in the <111>-oriented 3C–SiC films, the microstructure changed from mainly equiaxed grains to large columnar grains. The high-density stacking faults in <111>-oriented 3C–SiC films may lead to the identification of the nominal 2H, 4H and 6H polytypes by Raman spectra and EBSD. The (0001) planes of 2H-, 4H–SiC are perpendicular to the growth direction, while that of 6H–SiC are parallel.     

~(15)N标记的苯基五唑的合成、表征及分解反应机理

以15 N标记的亚硝酸钠和叠氮化钠为原料,低温下合成出15 N标记的对甲氧基苯基五唑(p-MOPP)和对叔丁基苯基五唑(p-tBPP)。利用低温1 H NMR、13 C NMR和15 N NMR等一维核磁技术及gHSQC和gHMBC等二维核磁技术进行了p-tBPP的1 H、13 C、15 N NMR谱化学位移全归属。通过变温1 H NMR和15 N NMR研究了五唑化合物的稳定性,推测了其分解反应机理。     

1H Nuclear Magnetic Resonance Study of Melt Polycondensation of 4,4′-Sulphonyldiphenol with Methyl- and Chloromethylphosphonic Dichloride

Melt polycondensation of 4,4′-sulphonyldiphenol with methylphosphonic dichloride and chloromethylphosphonic dichloride, respectively, was studied by taking samples from time to time and recording their ¹H n.m.r. spectra. Analysis of the spectra provided identification of the intermediate structures present during the reaction. Complete spectral assignments were made, and the effect of the substitution on the chemical shifts was measured. No kinetic calculations were made, owing to the inhomogeneity of the reaction mixtures.     

AU(DIEN)Cl]Cl(2): Exchange Phenomena Observed by H and C NMR Spectroscopy

The solution behaviour of the square-planar gold(III) complex [Au(dien)Cl]Cl(2) (dien = 1,5- diamino-3-azapentane) was investigated by (13)H and (13)C NMR spectroscopy. We have found that (1)H NMR spectra of [Au(dien)Cl] Cl(2) are characterised by exchange behaviour over the whole pH range, and some exchange effects are also seen in (13)C NMR spectra of the deprotonated hydroxo derivative of the complex in alkaline solution. An exchange rate of > 378 s(-1) was determined from (1)H NMR spectra at pH *(2) (coalescence temperature (40)C degrees ). In slightly acidic solutions of the complex, (1)H chemical shifts are in accordance with the known deprotonation of the central amine group of the complexed diethylenetriamine ligand. In (13)C NMR spectra, two separate sets of resonances are observed for the chloro and the hydroxo complex of gold(III) diethylenetriamine. The hydroxo complex [Au(dien-H)OH(+) shows exchange effects in (13)C NMR spectra. Variable temperature studies show the carbon atoms next to the central secondary amine to be inequivalent and each present in two different environments that are in intermediate to fast exchange on the NMR time-scale.     

六烯丙基六氮杂异伍兹烷的核磁表征

为精确表征六烯丙基六氮杂异伍兹烷(HAIW)的化学结构,在氘代氯仿(CDCl3)及氘代丙酮(acetone-d6)中研究了HAIW的核磁谱图特征。采用一维及二维1 H、13 C、15 N NMR技术对HAIW的NMR信号进行了全归属,利用核磁模拟软件NMR-SIM对氢谱图进行计算机拟合。结果表明,HAIW在丙酮溶液中的1 H NMR的分辨率较好,谱图中存在两类异伍兹烷信号(环内与桥头)及两类烯丙基碳氢信号,其中五元环所连4个烯丙基不能自由旋转导致亚甲基氢不对称出现2组峰,而六元环所连2个烯丙基则能自由旋转使得该亚甲基氢对称重合;两类烯丙基存在的多种偶合使得氢谱谱线较为复杂;由拟合氢谱化学位移及偶合常数获得的1 H NMR谱图与实际图谱完全一致。表明二维核磁共振技术与核磁模拟技术相结合,可用于对复杂谱的精确分析。     

The study of natural epoxy oils and epoxidized vegetable oils by13C nuclear magnetic resonance spectroscopy

The¹³C nuclear magnetic resonance spectra ofVernonia galamensis seed oil and of epoxidized palm super olein, soybean oil and linseed oil have been recorded and interpreted. The chemical shifts of the major signals are assigned and semi-quantitative results are derived. The spectroscopic procedure provides a useful method of analyzing oils that contain epoxy acids. The epoxide function differs from a double bond in its influence on the chemical shifts of nearby carbon atoms.     

Characterization of all Six Mono -Methylchrysenes by NMR and MS

Complete assignment of the 1 H and 13 C resonances of the methylchrysenes ( 1 - 6 ) were accomplished using 1D and 2D NMR techniques. Shift increments were calculated for the six mono -methyl isomers, showing the similarity of the positions 1 and 6, 2 and 3, and 4 and 5 in these systems. Simulation of the 13 C NMR spectra gave large differences in chemical shifts compared to the experimental values. The mass spectra of chrysene ( 7 ) with methyl substituent in all six possible positions were similar and very simple, containing little structural information.     

Errors in the Calculation of 27Al Nuclear Magnetic Resonance Chemical Shifts

Computational chemistry is an important tool for signal assignment of ²⁷Al nuclear magnetic resonance spectra in order to elucidate the species of aluminum(III) in aqueous solutions. The accuracy of the popular theoretical models for computing the ²⁷Al chemical shifts was evaluated by comparing the calculated and experimental chemical shifts in more than one hundred aluminum(III) complexes. In order to differentiate the error due to the chemical shielding tensor calculation from that due to the inadequacy of the molecular geometry prediction, single-crystal X-ray diffraction determined structures were used to build the isolated molecule models for calculating the chemical shifts. The results were compared with those obtained using the calculated geometries at the B3LYP/6-31G(d) level. The isotropic chemical shielding constants computed at different levels have strong linear correlations even though the absolute values differ in tens of ppm. The root-mean-square difference between the experimental chemical shifts and the calculated values is approximately 5 ppm for the calculations based on the X-ray structures, but more than 10 ppm for the calculations based on the computed geometries. The result indicates that the popular theoretical models are adequate in calculating the chemical shifts while an accurate molecular geometry is more critical.     

Assignment of the nonexchanging protons of the alpha-spectrin SH3 domain by two- and three-dimensional 1H-13C solid-state magic-angle spinning NMR and comparison of solution and solid-state proton chemical shifts

The assignment of nonexchanging protons of a small microcrystalline protein, the alpha-spectrin SH3 domain (7.2 kDa, 62 residues), was achieved by means of three-dimensional (3D) heteronuclear (1H-13C-13C) magic-angle spinning (MAS) NMR dipolar correlation spectroscopy. With the favorable combination of a high B(0)-field, a moderately high spinning frequency, and frequency-switched Lee-Goldburg irradiation applied during 1H evolution, a proton linewidth < or =0.5 ppm at 17.6 Tesla was achieved for the particular protein preparation used. A comparison of the solid-state 1H chemical shifts with the shifts found in solution shows a remarkable similarity, which reflects the identical protein structures in solution and in the solid. Significant differences between the MAS solid- and liquid-state 1H chemical shifts are only observed for residues that are located at the surface of the protein and that exhibit contacts between different SH3 molecules. In two cases, aromatic residues of neighboring SH3 molecules induce pronounced upfield ring-current shifts for protons in the contact area.