1H and 13C NMR studies of glycine in anisotropic media: double-quantum transitions and the effects of chiral interactions

The (1)H NMR spectrum of glycine in stretched gelatin gel and in cromolyn liquid crystal displays a well-resolved doublet due to (1)H-(1)H dipolar interaction. Multiple spectra were obtained within a wide range of offset frequencies of partially saturating radio-frequency (RF) radiation to generate steady-state irradiation envelopes or z-spectra of glycine. Maximal suppression of the doublet occurred when the irradiation was applied exactly at the centre frequency, between the two glycine peaks. This phenomenon is due to double-quantum transitions and is similar to our previous work on quadrupolar nuclei (2)H (HDO) and (23)Na(+). When the (13)C isotopomer glycine-2-(13)C was used, the same effect was found in twice, split by (1)J(CH)+2D(CH). Additional signals in (1)H and (13)C NMR due to prochiral-chiral interactions were found when glycine-2-(13)C was dissolved in chiral anisotropic gelatin and κ-carrageenan gels. The NMR spectra were successfully simulated assuming a (2)J(HH) coupling constant of -16.5Hz and two distinct dipolar coupling constants for the -(13)CH(2)- group (D(C,HA), and D(C,HB)).     

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.     

Towards hyperpolarized (13)C-succinate imaging of brain cancer

We describe a novel (13)C enriched precursor molecule, sodium 1-(13)C acetylenedicarboxylate, which after hydrogenation by PASADENA (Parahydrogen and Synthesis Allows Dramatically Enhanced Nuclear Alignment) under controlled experimental conditions, becomes hyperpolarized (13)C sodium succinate. Fast in vivo 3D FIESTA MR imaging demonstrated that, following carotid arterial injection, the hyperpolarized (13)C-succinate appeared in the head and cerebral circulation of normal and tumor-bearing rats. At this time, no in vivo hyperpolarized signal has been localized to normal brain or brain tumor. On the other hand, ex vivo samples of brain harvested from rats bearing a 9L brain tumor, 1 h or more following in vivo carotid injection of hyperpolarized (13)C sodium succinate, contained significant concentrations of the injected substrate, (13)C sodium succinate, together with (13)C maleate and succinate metabolites 1-(13)C-glutamate, 5-(13)C-glutamate, 1-(13)C-glutamine and 5-(13)C-glutamine. The (13)C substrates and products were below the limits of NMR detection in ex vivo samples of normal brain consistent with an intact blood-brain barrier. These ex vivo results indicate that hyperpolarized (13)C sodium succinate may become a useful tool for rapid in vivo identification of brain tumors, providing novel biomarkers in (13)C MR spectral-spatial images.     

硼替佐米的波谱学数据解析

对抗肿瘤药硼替佐米的紫外吸收光谱（UV）、红外吸收光谱（IR）、电喷雾离子源-质谱（ESI-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¹H和¹³C NMR谱峰进行了全归属,通过多种谱学技术确证了硼替佐米的结构.     

雷酚内酯的波谱学数据与结构确证

对雷酚内酯对照品的紫外吸收光谱（UV）、红外吸收光谱（IR）、质谱（MS）、核磁共振（NMR）谱（包括¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、NOE、¹H-¹³C HSQC和¹H-¹³C HMBC谱图）进行了分析,对其¹H和¹³C NMR谱峰进行了全归属,纠正了文献[5]的归属错误,确证了雷酚内酯对照品的化学结构.     

TRANILAST ^1H^13CNMR谱分析及其结构的鉴定

本文用COSY,CHCOR等二维核磁共振技术对TRANILAST,2[]3-(3.4-二甲基苯基)1-氧代-2-丙烯基]氨基]苯甲到进行了~1H、~(13)C NMR谱数据分析及归属,并结合~(13)C弛豫时间T_1 及变温实验对合成产品进行了结构鉴定.     

Fast Dissolution Dynamic Nuclear Polarization NMR of 13C-Enriched 89Y-DOTA Complex: Experimental and Theoretical Considerations

The yttrium complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra(1′-¹³C-acetic acid) [¹³C]DOTA was synthesized. Fast dissolution dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) studies revealed that the ⁸⁹Y, ¹³C, and ¹⁵N nuclei present in the complex could be co-polarized at the same optimum microwave irradiation frequency. The liquid-state spin–lattice relaxation time T ₁ of these nuclei were found to be reasonably long to preserve some or most of the DNP-enhanced polarization after dissolution. The hyperpolarized ¹³C and ⁸⁹Y NMR signals were optimized in different glassing mixtures. The overall results are discussed in light of the thermal mixing model of DNP.     

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.     

3，5-二甲基金刚胺盐酸盐的NMR研究

NMR核磁共振谱显示3，5-二甲基金刚胺盐酸盐是一个刚性结构，但其分子结构包含2个非对映体的立体构型形式. 我们通过利用DEPT，¹H-¹H COSY，HSQC和HMBC等技术所测得的二维谱图数据对NMR数据进行了完整的归属分析，其中¹³C NMR谱图显示在δ=29~54 ppm之间的十组峰表示所有碳的共振，而且由于不同的分子构象导致在¹³C NMR谱中有3个不同的季碳峰和¹H NMR中的2个不同的甲基峰. 由于H-5的叔碳H原子与邻近CH₂ 的平面二面夹角均约为600，致使耦合常数极其小，波谱仪难以分辨它们从而使¹H NMR峰为单重峰.     

2,2-二甲基-3-(2,2-二氯乙烯基)环丙烷羧酸乙(甲)酯及其合成中间体的结构测定

由异戊烯醇-原乙酸三乙（甲）酯法相继合成了拟除虫菊酯类农药中间体3，3-二甲基-4-戊烯酸乙（甲）酯，4，6，6，6-四氯-3，3-二甲基己酸乙（甲）酯和2，2-二甲基-3－（2，2-二氯乙烯基）环丙烷羧酸乙（甲）酯等化合物，对这些化合物进行了元素分析、红外光谱、1HNMR等测定，与文献结果相符，为了进一步明确结构，测定了未见报道的13CNMR，给出了波谱数据归属．     

新型拟肽cyclo[-RGD-ψ（triazole）-GD-]波谱学数据与结构确证

多肽RGD是一类含有精氨酸-甘氨酸-天冬氨酸(Arg-Gly-Asp)序列的短肽,该文对新型环状拟肽cyclo[-RGD-ψ(triazole)-GD-]的紫外吸收光谱(UV)、红外吸收光谱(FT-IR)进行了分析,并利用核磁共振(NMR)波谱(包括~1H NMR、~1H-~1H COSY、~(13C) NMR、DEPT、~1H-~(13)C HSQC和~1H-~(13)C HMBC)对其~1H和~(13)C NMR信号进行了全归属.     

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.     

Enhanced (13)C PFG NMR for the study of hydrodynamic dispersion in porous media

PFG NMR methods are frequently used as a means of probing both coherent and incoherent molecular motions of fluids contained within heterogeneous porous media. The time scale over which molecular displacements can be probed in a conventional PFG NMR experiment is limited by the relaxation characteristics of (1)H - the nucleus that is typically observed. In multiphase systems, due to its sensitivity to susceptibility gradients and interactions with surfaces,(1)H signal is frequently characterized by rapid T(1) and T(2) relaxation. In this work, a heteronuclear approach to PFG NMR is demonstrated which allows the study of molecular displacement over extended time scales (and, consequently, length scales) by exploiting the longer relaxation time of (13)C. The method presented employs the DEPT technique of polarization transfer in order to enhance both the sensitivity and efficiency of (13)C detection. This hybrid coherence transfer PFG technique has been used to acquire displacement propagators for flow through a bead pack with an observation time of up to 35 s.     

普卡必利的NMR研究

以4-氨基-5-氯-2,3-二氢苯并呋喃-7-羧酸和1-（3-甲氧基丙基）-4-哌啶胺为原料,通过酰胺缩合反应合成了普卡必利.普卡必利化学名为4-氨基-5-氯-2,3-二氢-N-[1-（3-甲氧基丙基）-4-哌啶基]-7-苯并呋喃甲酰胺,是二氢苯并呋喃的衍生物5-H4受体拮抗剂,是一种治疗慢性便秘的重要药物.普卡必利结构中存在多个化学环境非常接近的碳原子,核磁共振（NMR）谱图相对复杂.本文首先应用超高效液相色谱-串联质谱（UPLC-MS/MS）和液相色谱-高分辨质谱（LC-HRMS）对其元素组成进行了分析,进而用一维和二维NMR谱（包括¹H NMR、¹³C NMR、DEPT、¹H-¹HCOSY、¹H-¹³C HSQC、¹H-¹³C HMBC）对普卡必利的¹H和¹³C NMR信号进行了指认归属,确定了其结构.本工作对苯并呋喃衍生物及相关下游药物合成工艺的进一步优化,以及相关衍生药物的研究具有参考价值.     

卡巴他赛结构确证的波谱学研究

用红外吸收光谱、紫外吸收光谱、核磁共振（NMR）波谱（包含¹H NMR、¹³C NMR、DEPT-135、COSY、HSQC和HMBC）、质谱、差示扫描量热分析、X-射线粉末衍射和元素分析等方法对卡巴他赛原料药精制品进行了结构确证,对其所有的¹H和¹³C NMR信号进行了归属,同时讨论了质谱主要碎片离子可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式,通过多种波谱技术结合确证了卡巴他赛的结构．     

Nearly 10-fold enhancements in intermolecular H double-quantum NMR experiments by nuclear hyperpolarization

Intermolecular Multiple-Quantum Coherences (iMQCs) can yield interesting NMR information of high potential usefulness in spectroscopy and imaging – provided their associated sensitivity limitations can be overcome. A recent study demonstrated that ex situ dynamic nuclear polarization (DNP) could assist in overcoming sensitivity problems for iMQC-based experiments on ¹³C nuclei. In the present work we show that a similar approach is possible when targeting the protons of a hyperpolarized solvent. It was found that although the DNP procedure enhances single-quantum ¹H signals by about 600, which is significantly less than in optimized low-γ liquid-state counterparts, the non-linear dependence of iMQC-derived signals on polarization can yield very large enhancements approaching 10⁶. Cleary no practical amount of data averaging can match this kind of sensitivity gains. The fact that DNP endows iMQC-based ¹H NMR spectra with a sensitivity that amply exceeds that of their thermally polarized single-quantum counterpart, is confirmed in a number of simple single-scan 2D imaging experiments.     

富马酸替诺福韦二吡呋酯波谱数据与结构确证

对富马酸替诺福韦二吡呋酯的紫外吸收光谱(UV)、红外吸收光谱(IR)、质谱(ESIMS和HRMS)、核磁共振谱(¹H NMR,¹³C NMR,³¹P NMR,DEPT-135,COSY,HSQC和HMBC)、差热分析(DSC)和热重分析(TGA)报道并进行解析,对其所有的NMR谱信号进行归属,同时讨论质谱的主要碎片离子的可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式,通过多种谱学技术确证富马酸替诺福韦二吡呋酯的结构．     

阿立哌唑的谱学研究

对抗精神分裂症新药阿立哌唑的紫外光谱(UV)、红外光谱(IR)、核磁共振谱(NMR)以及质谱(MS)进行了解析。根据该化合物的紫外光谱探讨了其在溶液中的存在形式,讨论了红外光谱的特征吸收峰所对应的官能团的振动形式以及质谱的特征同位素离子峰,利用1H—1H cosy,HSQC,HMBC等二维核磁共振技术推断并确证了该化合物的结构,对NMR谱信号进行了归属,并根据化学位移、偶合常数以及二维相关谱分析了该化合物结构中的10个不同的亚甲基。     

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.     

In vivo measurement of normal rat intracellular pyruvate and lactate levels after injection of hyperpolarized [1-(13)C]alanine

Hyperpolarized technology utilizing dynamic nuclear polarization has enabled rapid and high-sensitivity measurements of ¹³C metabolism in vivo. The most commonly used in vivo agent for hyperpolarized ¹³C metabolic imaging thus far has been [1-¹³C]pyruvate. In preclinical studies, not only is its uptake detected, but also its intracellular enzymatic conversion to metabolic products including [1-¹³C]lactate and [1-¹³C]alanine. However, the ratio of ¹³C-lactate/¹³C-pyruvate measured in this data does not accurately reflect cellular values since much of the [1-¹³C]pyruvate is extracellular depending on timing, vascular properties, and extracellular space and monocarboxylate transporter activity. In order to measure the relative levels of intracellular pyruvate and lactate, in this project we hyperpolarized [1-¹³C]alanine and monitored the in vivo conversion to [1-¹³C]pyruvate and then the subsequent conversion to [1-¹³C]lactate. The intracellular lactate-to-pyruvate ratio of normal rat tissue measured with hyperpolarized [1-¹³C]alanine was 4.89±0.61 (mean±S.E.) as opposed to a ratio of 0.41±0.03 when hyperpolarized [1-¹³C]pyruvate was injected.