固体高分辨DNP CP/MAS探头的研制及DNP实验技术的探讨

介绍了自行研制的用于动态核极化实验的固体高分辨CP/MAS探头,给出了典型含自由基固体样品的DNP增强高分辨NMR谱.并对动态核极化实验中的技术问题进行了讨论,提出了相应的解决方法.     

靶向新药吉非替尼的核磁共振波谱研究

应用1D、2D NMR实验技术（¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、¹H-¹³C HMQC、¹H-¹³C HMBC等）研究了靶向新药吉非替尼的结构,对其1H NMR和¹³C NMR谱峰作了全归属,并讨论了F原子对吉非替尼的¹H、¹³C NMR的影响.     

依卡倍特钠的波谱学数据解析

对胃粘膜保护剂依卡倍特钠的紫外吸收光谱（UV）、红外吸收光谱（IR）、高分辨-质谱（HR-MS）、核磁共振（NMR）波谱（包括¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、¹H-¹³C HSQC和¹H-¹³C HMBC）数据进行了解析,对其所有的¹H和¹³C NMR谱信号进行了归属,通过多种谱学技术确证了依卡倍特钠的结构.     

固态富马酸单乙酯在变温1H MAS与CRAMPS研究

富马酸单乙酯(FAME)的单脉冲¹H MAS谱由-高分辨成分与-宽线谱成分组成.高分辨成分可由Hahn回波脉冲序列单独获得.文中通过变温¹H MAS与CRAMPS实验对两组分的性质进行了系统的研究.发现当温度趋于样品的熔点时,其¹H CRAMPS谱可观察到化学位移明显区别的两套谱,它们分别对应于¹H MAS谱的高分辨与宽线组分.实验表明:高分辨成分来自FAME样品的-塑性相,而宽线组分来自通常的刚性相.文中所给出的实验事实充分说明¹H MAS与CRAMPS技术是研究有机塑性固体的强有力的工具.     

固体中13C CP/MAS谱编辑一些改进

本文将基本的谱编辑脉冲序列与消旋转边带的TOSS脉冲序列联用,可以实现强磁场下¹³C CP/MAS谱编辑.通常,固体中非质子化碳与甲基碳的自旋晶格弛豫时间差别很大,此差别可作为谱编辑过程中区分它们的一条附加判据.对具有复杂分子结构的体系,此判据的作用尤其重要.文中的实例将表明:一个完整的¹³C CP/MAS谱编辑一般可通过SCPTOSS谱(短接触时间交叉极化谱);SCPPITOSS (短接触时间交叉极化极化反转)谱,LCPDTOSS (长接触时间交叉极化及去极化)谱及部分弛豫的LCPDTOSS谱适当组合而得到.     

南海海绵Dysidea fragilis中两个倍半萜内酯的NMR研究

用一维¹H、¹³C NMR谱、DEPT ¹³C NMR谱、选择性远程DEPT ¹³C NMR、¹H-¹H COSY和¹³C-¹H COSY二维核磁共振技术研究了南海海绵Dysidea fragilis中的两个倍半萜herbadysidolide(1)和furodysinin lactone(2),确认了化学结构,并对其¹³C NMR和¹H NMR谱进行了归属.药理活性试验表明:1和2具有一定的心血管活性.     

Lasiodonin Acetonide的NMR数据解析

对lasiodonin acetonide进行了¹H和¹³C NMR检测，参考lasiodonin, maoecrystal T, wikstroemioidin B和rabdocoetsin A的¹H、¹³C NMR数据，通过DEPT和¹H-¹H COSY、HSQC、HMBC等2D NMR技术对该化合物所有的¹H和¹³C NMR信号进行了全归属和详细解析.     

先进固体NMR技术研究高分子结构与动力学

随着固体NMR理论和谱仪硬件技术的不断发展,近年来固体NMR技术在高分子多尺度结构与动力学研究领域中正发挥着越来越重要的作用. 多脉冲及高速魔角旋转（MAS）等质子高分辨技术的发展使得高灵敏度的¹H谱可有效地用于高分子化学结构与链间相互作用的检测;基于化学键（J-耦合）相关和通过空间（偶极耦合）相互作用的各种二维异核相关谱NMR新技术,使得复杂高分子的链结构得以严格解析. 基于MAS下同核和异核偶极-偶极相互作用、化学位移各向异性等各向异性相互作用重聚的系列新技术,使得研究者可在采用高分辨¹H或¹³C 检测信号的同时检测准静态下的各向异性相互作用,进而获得与之密切相关的结构和动力学信息. 通过质子偶极滤波技术可有效检测多相聚合物中的界面相与相区尺寸、高分子共混物中的相容性等问题. 在动力学的研究中,通过质子间自旋扩散的有效压制技术和化学位移各向异性的重聚,目前已经可以有效地获取链段上单个化学键的快速局域运动以及链段的超慢分子运动. 上述丰富的多尺度NMR技术可以使研究者在不同空间和时间尺度上对高分子聚合物的微观结构、相分离和动力学行为等进行详细的研究,进而阐明高分子微观结构与宏观性能的关联. 该文以固体NMR中最主要的2类核（¹H和¹³C）的检测技术为主线,简单介绍近年来固体NMR领域的一些最新研究进展及其在高分子结构和动力学研究中的应用.     

新型连翘脂素-布洛芬酯合物的波谱学数据解析

以连翘脂素和布洛芬为原料,通过Schotten-Baumann酯化合成了酯合物——连翘脂素-布洛芬酯.对其紫外吸收光谱（UV）、红外吸收光谱（IR）、基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）、1D和2D核磁共振（NMR）波谱（包括¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、¹H-¹H NOESY、¹H-¹³C HSQC和¹H-¹³C HMBC）进行了解析,对其¹H和¹³C NMR谱峰进行了全归属.     

一种热转印色素的1H、13C NMR研究

报道了一种热转印色带用黄染料的¹H、¹³C NMR , 应用¹H NMR、¹³C NMR、定量碳谱、DEPT、¹H-¹H COSY、HMQC、HMBC等确定了其在氘代氯仿中的分子结构, 并对全部谱峰进行了归属, 探索了黄染料在氘代氯仿中的结构对¹³C、¹H NMR谱图化学位移及谱峰裂分的影响.      

Sensitivity enhancement, assignment, and distance measurement in 13C solid-state NMR spectroscopy for paramagnetic systems under fast magic angle spinning

Despite success of previous studies, high-resolution solid-state NMR (SSNMR) of paramagnetic systems has been still largely unexplored because of limited sensitivity/resolution and difficulty in assignment due to large paramagnetic shifts. Recently, we demonstrated that an approach using very-fast magic angle spinning (VFMAS; spinning speed 20kHz) enhances resolution/sensitivity in (13)C SSNMR for paramagnetic complexes [Y. Ishii, S. Chimon, N.P. Wickramasinghe, A new approach in 1D and 2D (13)C high resolution solid-state NMR spectroscopy of paramagnetic organometallic complexes by very fast magic-angle spinning, J. Am. Chem. Soc. 125 (2003) 3438-3439]. In this study, we present a new strategy for sensitivity enhancement, signal assignment, and distance measurement in (13)C SSNMR under VFMAS for unlabeled paramagnetic complexes using recoupling-based polarization transfer. As a robust alternative of cross-polarization (CP), rapid application of recoupling-based polarization transfer under VFMAS is proposed. In the present approach, a dipolar-based analog of INEPT (dipolar INEPT) methods is used for polarization transfer and a (13)C signal is observed under VFMAS without (1)H decoupling. The resulting low duty factor permits rapid signal accumulation without probe arcing at recycle times ( approximately 3 ms/scan) matched to short (1)H T(1) values of small paramagnetic systems ( approximately 1 ms). Experiments on Cu(dl-Ala)(2) showed that the fast repetition approach under VFMAS provided sensitivity enhancement by a factor of 8-66 for a given sample, compared with the (13)C MAS spectrum under moderate MAS at 5kHz. The applicability of this approach was also demonstrated for a more challenging system, Mn(acac)(3), for which (13)C and (1)H paramagnetic shift dispersions reach 1500 and 700 ppm, respectively. It was shown that effective-evolution-time dependence of transferred signals in dipolar INEPT permitted one to distinguish (13)CH, (13)CH(2), (13)CH(3), (13)CO2- groups in 1D experiments for Cu(DL-Ala)(2) and Cu(Gly)(2). Applications of this technique to 2D (13)C/(1)H correlation NMR under VFMAS yielded reliable assignments of (1)H resonances as well as (13)C resonances for Cu(DL-Ala)(2) and Mn(acac)(3). Quantitative analysis of cross-peak intensities in 2D (13)C/(1)H correlation NMR spectra of Cu(DL-Ala)(2) provided distance information between non-bonded (13)C-(1)H pairs in the paramagnetic system.     

A 4-mm probe for (13)C CP/MAS NMR of solids at 21.15 T

The design of a broadband 4-mm magic-angle spinning (MAS) X-(1)H/(19)F double resonance probe for cross-polarization (CP)/MAS NMR studies at 21.15 T ((1)H at 900 MHz) is described. The high-frequency (1)H/(19)F channel employs a new and efficient transmission line tuning design. The first (13)C CP/MAS NMR spectra recorded at 21.15 T have been obtained with this probe and exhibit the best S/N per milligram sample of hexamethylbenzene achieved so far for a 4-mm rotor.     

Characterization of polyalkylvinyl ether phases by solid-state and suspended-state nuclear magnetic resonance investigations

Pure organic polyalkylvinyl ether phases were synthesized by suspension polymerization using different ratios and compositions of n-butylvinyl ether (C₄VE) and n-octadecylvinyl ether (C₁₈VE) with triethylene glycol divinyl ether or divinylbenzene as crosslinkers, respectively. These phases were investigated by means of solid-state ¹³C cross-polarization magic angle spinning nuclear magnetic resonance (NMR) spectroscopy and ¹H high-resolution magic angle spinning (HR MAS) NMR spectroscopy in suspended-state. A comparison of these two methods showed the substantial advantages of ¹H HR MAS NMR measurements. Structure elucidation was achieved using a 2D H,H-COSY NMR experiment performed under MAS conditions enabling full peak assignment of the ¹H NMR spectra of these phases. The dynamic behavior of the polyalkylvinyl ether phases was determined by employing temperature-dependent measurements of spin–lattice relaxation times (T₁) as well as accumulation of a 2D wide line separation NMR spectrum.     

High resolution 2D 1H-13C correlation of cholesterol in model membrane

High resolution 2D NMR MAS spectra of liposomes, in particular 1H-13C chemical shifts correlations have been obtained on fluid lipid bilayers made of pure phospholipids for several years. We have investigated herein the possibility to obtain high resolution 2D MAS spectra of cholesterol embedded in membranes, i.e. on a rigid molecule whose dynamics is characterized mainly by axial diffusion without internal segmental mobility. The efficiency of various pulse sequences for heteronuclear HETCOR has been compared in terms of resolution, sensitivity and selectivity, using either cross polarization or INEPT for coherence transfer, and with or without MREV-8 homonuclear decoupling during t1. At moderately high spinning speed (9 kHz), a similar resolution is obtained in all cases (0.2 ppm for 1H(3,4), 0.15 ppm for 13C(3,4) cholesterol resonances), while sensitivity increases in the order: INEPT < CP(x4) < CP + MREV. At reduced spinning speed (5 kHz), the homonuclear dipolar coupling between the two geminal protons attached to C(4) gives rise to spinning sidebands from which one can estimate a H-H dipolar coupling of 10 kHz which is in good agreement with the known dynamics of cholesterol in membranes.     

A solid-state NMR application of the anomeric effect in carbohydrates: galactosamine, glucosamine, and N-acetyl-glucosamine

Simple 2D 13C/15N heteronuclear correlation solid-state NMR spectroscopy was implemented to resolve the 15N resonances of the alpha and beta anomers of three amino monosaccharides: galactosamine (GalN), glucosamine hydrochloride (GlcN), and N-acetyl-glucosamine (GlcNAc) labeled specifically with 13C1/15N spin pairs. Although the 15N resonances could not be distinguished in normal 1D spectra, they were well resolved in 2D double CP/MAS correlation spectra by taking advantage of the 13C spectral resolution. The alpha and beta resonances shifted apart by 3-5 ppm in their 13C chemical shifts, and differed by 1-2 ppm in the extended 15N dimension. Aside from this, the detection of other 13C/15N correlations over short distances was also achieved arising from the C2, C3 and CO carbons present in natural abundance. 2D double CP/MAS chemical shift correlation NMR spectroscopy is a simple and powerful technique to characterize the anomeric effect of amino monosaccharides. Applications of the 2D method reveal well-resolved 15N and 13C chemical shifts might be useful for structural determination on carbohydrates of biological significance, such as glycopeptide or glycolipids.     

PRISE THE SECRET OF HETEROGENEITY OUT OF BIOPOLYMER SYSTEMS

High-resolution 13C spectra of solid polymers are often acquired with cross polarization with magic angle spinning (CP/MAS) to take advantage of the abunda ntly available protons in the polymer chains. The sequence for transferring mag netization from 1H to13C using Hartmann-Hahn spin locking in the rotating frame is now a standard in commercial solidstate NMR spectrometers.     

~(13)C CP/MAS OF MOTIONS IN SOLID POLYMERS

High-resolution 13C spectra of solid polymers are often acquired with cross polarization with magic angle spinning (CP/MAS) to take advantage of the abunda ntly available protons in the polymer chains. The sequence for transferring mag netization from 1H to13C using Hartmann-Hahn spin locking in the rotating frame is now a standard in commercial solidstate NMR spectrometers.     

精确测量慢魔角旋转条件下碳氢偶极谱

发展了精确测量二维固体魔角旋转条件下碳氢偶极谱的方法，用以分析固体高分子分子运动，并给出了全同立构聚丙烯的实验谱.     

Rapid solid-state NMR of deuterated proteins by interleaved cross-polarization from ¹H and ²H nuclei

We present a novel sampling strategy, interleaving acquisition of multiple NMR spectra by exploiting initial polarization subsequently from (1)H and (2)H spins, taking advantage of their different T(1) relaxation times. Different (1)H- and (2)H-polarization based spectra are in this way simultaneously recorded improving either information content or sensitivity by adding spectra. The so-called Relaxation-optimized Acquisition of Proton Interleaved with Deuterium (RAPID) (1)H→(13)C/(2)H→(13)C CP/MAS multiple-acquisition method is demonstrated by 1D and 2D experiments using a uniformly (2)H, (15)N,(13)C-labeled α-spectrin SH3 domain sample with all or 30% back-exchanged labile (2)H to (1)H. It is demonstrated how 1D (13)C CP/MAS or 2D (13)C-(13)C correlation spectra initialized with polarization from either (1)H or (2)H may be recorded simultaneously with flexibility to be added or used individually for spectral editing. It is also shown how 2D (13)C-(13)C correlation spectra may be recorded interleaved with (2)H-(13)C correlation spectra to obtain (13)C-(13)C correlations along with information about dynamics from (2)H sideband patterns.