一些高级NMR技术介绍

对一些二维NMR技术,例如^1H-^1H相关谱（^1H-^1H COSY),^1H-^13C杂核化学位移相关谱（^1H-C^13 COSY）,奥氏核效应交换相关谱（NOESY）作了介绍,列举了一些典型谱图。     

人体尿液代谢组NMR分析

利用固相萃取分离和核磁共振技术（nuclear magnetic resonance,NMR）对人体尿液中的代谢物进行了较为系统的研究。通过对人体尿液样品固相莘取后分离得到的五个组分^1H NMR,同核二维氢谱（correlation spectroscopy,COSY）和全相关谱（total correlation spectroscopy,TOCSY）,异核相关光谱（heteronuclear single quantum correlation,HSQC和Heteronuclear muptiple bond correlation,HMBC）,J-分解谱（J-resolved spectroscopic,J-RES）的谱图分析,解析出了74种化合物的^1H和^13C化学位移,并对一维^1H谱的多数谱峰进行了有效指认。     

四氟菊酯的核磁共振法分析

采用^1HNMR、^13C NMR、无畸变增强极化转移实验(DEPT)、^1H—^1H相关谱(COSY)、^1H检测异核多量子相关谱(HMQC)、^1H检测的异核多键相关谱(HMBC)等方法，对四氟菊酯的^1H和^13C NMR谱信号进行了归属；并用奥氏核效应(NOE)差谱法确定了该化合物的立体结构，为其结构鉴定和生产过程中的质量控制提供了重要依据。     

用2D NMR确定金色酰胺醇酯的结构

从中国南海红藻鹧鸪菜（Caloglossa leprieurii）中首次分离得到二肽金色酰胺醇酯(aurantiamide acetate)。利用^1H－^1H COSY、^13C－^1H COSY、HMBC等二维谱手段鉴定了该化合物的结构,对其^1H和^13C NMR的信号进行了归属,并且确定了其绝对构型。     

新型有机光致变色材料螺嗪的结构确证

采用^1H NMR谱、^13C NMR谱、DEPT（θ=3π/4）谱、红外吸收光谱、质谱等仪器分析手段确证了4种新合成的有机光致变色材料螺E嗪化合物的结构,并对化合物的^13C NMR谱化学位移和质谱碎片进行了归属和确认。     

毛冬青甲素的核磁共振法分析

采用^1H、^13C、DEPT(无畸变极化转移增益法)、^1H-^1 COSY(氢-氢化学位移相关谱)、HMQC(异核多量子相关谱)、HMBC(异核多键相关谱)、NOESY(二维核欧沃豪斯效应谱)等多种NMR分析方法,对毛冬青甲素的^1H和^13C NMR谱信号进行了归属;并对生产过程常同时存在的丁二酸二钠也进行了谱线归属,提出通过^1H NMR法对产品中的丁二酸二钠进行定量测定。为其结构鉴定和生产过程中的质量控制提供了重要依据。     

脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

辛伐他汀的波谱学数据和结构确证

对辛伐他汀的红外(IR)、紫外(UV)、质谱(MS)、氢-氢相关谱(^1H-^1HCOSY)、碳谱(^13C NMR,DEPT)、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)予以解析并进行了报道,对所有的^1H NMR和^13C NMR谱信号进行了归属;讨论了红外特征吸收峰所对应的官能团的振动形式,并且对样品进行热差和热重分析,显示该样品为单一晶型,不含结晶水。     

含二氮杂萘酮单元双官能团化合物结构的波谱表征

在成功地合成了11个用于制备聚芳酰胺类聚合物的含二氮杂萘酮单元的双官能团化合物基础上,本实验用核磁共振波谱确定了各化合物的结构。用二维同核位移相关谱(gCOSY)、异核^13C-^1H-键相关谱(gHSQC)和异核^13C-^1H远程相关谱(gHMBC)完成了全部^1H和^13C NMR谱带的归属;首次报道了该系列衍生物的氢和碳原子的化学位移值。对其系列化合物的核磁共振波谱及红外光谱的特征进行了讨论。     

咪喹莫特的波谱学数据与结构表征

对咪喹莫特的红外(IR)、紫外(UV)、质谱(MS)、氢-氢相关谱(^1H--^1H COSY)、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)予以解析并进行了报道。对所有的^1H NMR、^13C NMR谱的信号进行了归属；讨论了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。     

A complete 1H and 13C NMR data assignment for the diterpene methyl (-)-zanzibarate by 2D spectroscopy and NOE experiments

The 1H and 13C NMR spectra of methyl (-)-zanzibarate (1), an ent-labdanic diterpene isolated from the epicarp of Hymenaea courbaril var. altissima (Leguminosaea, Cesalpinoideae, Detariae), was fully assigned by COSY experiments, 13C/1H shift correlation diagrams and NOE experiments.     

2D NMR方法研究抗癌药物冬凌草乙素的结构与谱线归属

用异核化学位移相关谱、远程异核化学位移相关谱和同核化学位移相关谱等现代核磁共振技术对抗癌中草药冬凌草中分离出的抗癌、抗菌有效成分冬凌草乙素分子的~(13)C和~1H化学位移进行了完全归属,为冬凌草乙素分子溶液中的三维空间结构研究提供了可靠的结构参数。     

Solid-state NMR characterization and determination of the orientational order of a nematogen

Thermotropic liquid crystalline compounds are of considerable importance due to their potential applications as advanced functional materials. A mesogen consisting of a terminal dimethylamino group, which can act as a charge-transfer donor, is particularly valuable for its light emission and nonlinear optical properties. In this study, we report the solid-state NMR investigation of the nematic behavior of one such novel mesogen (4-(dodecyloxy)benzoic acid 4-[((4-(dimethylamino)phenyl)imino)methyl]phenyl ester). Static and MAS experiments were performed on nematic and crystalline phases of the compound to measure (13)C chemical shift, (13)C-(1)H dipolar coupling, and (1)H chemical shift values. 2D chemical shift correlation of (1)H and (13)C nuclei confirmed the (13)C chemical shift values determined from 1D CPMAS experiments. The appearance of more peaks in both CPMAS and (13)C-(1)H HETCOR spectra of a crystalline solid suggests the heterogeneous orientations of phenyl rings of the mesogenic core. Variable-temperature experiments infer the motional averaging of these orientations before melting. The (1)H-(13)C dipolar coupling values, measured by 2D PITANSEMA experiments, were used to determine the orientational order of the mesogenic core at various temperatures. The influence of the linking unit and terminal substituents on the order parameter values of the mesogenic core is discussed.     

A complete 1H and 13C NMR data assignment for four drimane sesquiterpenoids isolated from Drimys winterii

From the bark of Drimys winterii Forst., the drimane derivatives drimendiol, polygodial, isotadeonal and isodrimeninol were isolated. Complete and unambiguous 1H and 13C NMR chemical shift assignments of these compounds were achieved by COSY experiments, 13C/1H shift correlation diagrams and NOE experiments. Isotadeonal and isodrimeninol were found for the first time in this plant species.     

NMR study of the spatial structure of synthetic pyrethroids

The spatial isomers of the new synthetic analogs of ethyl permithrinic ether and permethrin were investigated by NMR (¹H, ¹³C, DEPT (distortionless enhancement by polarization transfer), COSY (correlation spectroscopy), CHCORR (heteronuclear (C, H) shift correlation spectroscopy), ROESY (rotating-frame Overhauser effect spectroscopy)). Several tendencies were revealed in the ¹H and ¹³C chemical shifts of the α atoms of the substituents in the 2nd and 3rd positions of the cyclopropane ring. For substituents cis-orientated relative to the ester group, the spectra show a paramagnetic shift of the ¹H signals and the diamagnetic shift of the ¹³C signals relative to the trans-orientated substituents. The ¹H and ¹³C chemical shifts of the α atoms of the substituents in the 2nd and 3rd positions of the cyclopropane ring permit an unambiguous determination of the stereochemistry of ethyl permethrinic ether and permethrin analogs.     

Molecular structure, IR and NMR spectra of 2,6 distyrylpyridine by density functional theory and ab initio Hartree-Fock calculations

Vibrational frequencies and gauge including atomic orbital (GIAO) 13C NMR and 1H NMR chemical shift values of 2,6 distyrylpyridine (C21H17N) in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31G(d) basis set. These methods are proposed as a tool to be applied in the structural characterization of 2,6 distyrylpyridine (C21H17N). The title compound has C2v point group, thus providing useful support in the interpretation of experimental IR data. In addition, obtained results were related to the linear correlation plot of experimental 13C NMR, 1H NMR chemical shifts values and IR data.     

新药普卢利沙的核磁共振研究

应用同核化学位移相关谱(1H-1H COSY)、氢检出异核多量子相关谱(HMQC)、氢检出多键异核多量子相关谱(HMBC)等二维谱核磁共振技术,参考19F-1H和19F-13C的偶合裂分情况对抗菌新药普卢利沙的1H NMR、13C NMR谱的信号进行了全归属。     

Toward direct determination of conformations of protein building units from multidimensional NMR experiments VI: chemical shift analysis of his to gain 3D structure and protonation state information

NMR--chemical shift structure correlations were investigated by using GIAO-RB3LYP/6-311++G(2d,2p) formalism. Geometries and chemical shifts (CSI values) of 103 different conformers of N'-formyl-L-histidinamide were determined including both neutral and charged protonation forms. Correlations between amino acid torsional angle values and chemical shifts were investigated for the first time for an aromatic and polar amino acid residue whose side chain may carry different charges. Linear correlation coefficients of a significant level were determined between chemical shifts and dihedral angles for CSI[(1)H(alpha)]/phi, CSI[(13)C(alpha)]/phi, and CSI[(13)C(alpha)]/psi. Protonation of the imidazole ring induces the upfield shift of CSI[(13)C(alpha)] for positively charged histidines and an opposite effect for the negative residue. We investigated the correspondence of theoretical and experimental (13)C(alpha), (13)C(beta), and (1)H(alpha) chemical shifts and the nine basic conformational building units characteristic for proteins. These three chemical shift values allow the identification of conformational building units at 80% accuracy. These results enable the prediction of additional regular secondary structural elements (e.g., polyProlineII, inverse gamma-turns) and loops beyond the assignment of chemical shifts to alpha-helices and beta-pleated sheets. Moreover, the location of the His residue can be further specified in a beta-sheet. It is possible to determine whether the appropriate residue is located at the middle or in a first/last beta-strand within a beta-sheet based on calculated CSI values. Thus, the attractive idea of establishing local residue specific backbone folding parameters in peptides and proteins by employing chemical shift information (e.g., (1)H(alpha) and (13)C(alpha)) obtained from selected heteronuclear correlation NMR experiments (e.g., 2D-HSQC) is reinforced.     

G-matrix Fourier transform NOESY-based protocol for high-quality protein structure determination

A protocol for high-quality structure determination based on G-matrix Fourier transform (GFT) NMR is presented. Five through-bond chemical shift correlation experiments providing 4D and 5D spectral information at high digital resolution are performed for resonance assignment. These are combined with a newly implemented (4,3)D GFT NOESY experiment which encodes information of 4D 15N/15N-, 13C(alipahtic)/15N-, and 13C(aliphatic)/13C(aliphatic)-resolved [1H,1H]-NOESY in two subspectra, each containing one component of chemical shift doublets arising from 4D --> 3D projection at omega1:Omega(1H) +/- Omega(X) [X = 15N,13C(aliphatic)]. The peaks located at the centers of the doublets are obtained from simultaneous 3D 15N/13C(aliphatic)/13C(aromatic)-resolved [1H,1H]-NOESY, wherein NOEs detected on aromatic protons are also obtained. The protocol was applied for determining a high-quality structure of the 14 kDa Northeast Structural Genomics consortium target protein, YqfB (PDB ID ). Through-bond correlation and NOESY spectra were acquired, respectively, in 16.9 and 39 h (30 h for shift doublets, 9 h for central peaks) on a 600 MHz spectrometer equipped with a cryogenic probe. The rapidly collected highly resolved 4D NOESY information allows one to assign the majority of NOEs directly from chemical shifts, which yields accurate initial structures "within" approximately 2 angstroms of the final structure. Information theoretical "QUEEN" analysis of initial distance limit constraint networks revealed that, in contrast to structure-based protocols, such NOE assignment is not biased toward identifying additional constraints that tend to be redundant with respect to the available constraint network. The protocol enables rapid NMR data collection for robust high-quality structure determination of proteins up to approximately 20-25 kDa in high-throughput.     

Toward direct determination of conformations of protein building units from multidimensional NMR experiments. V. NMR chemical shielding analysis of N-formyl-serinamide,a model for polar side-chain containing peptides

Knowledge of chemical shift-structure relationships could greatly facilitate the NMR chemical shift assignment and structure refinement processes that occur during peptide/protein structure determination via NMR spectroscopy. To determine whether such correlations exist for polar side chain containing amino acid residues the serine dipeptide model, For-L-Ser-NH(2), was studied. Using the GIAO-RHF/6-31+G(d) and GIAO-RHF/TZ2P levels of theory the NMR chemical shifts of all hydrogen ((1)H(N), (1)H(alpha), (1)H(beta1), (1)H(beta2)), carbon ((13)C(alpha), (13)C(beta), (13)C') and nitrogen ((15)N) atoms have been computed for all 44 stable conformers of For-L-Ser-NH(2). An attempt was made to establish correlation between chemical shift of each nucleus and the major conformational variables (omega(0), phi, psi, omega(1), chi,(1) and chi(2)). At both levels of theory a linear correlation can be observed between (1)H(alpha)/phi, (13)C(alpha)/phi, and (13)C(alpha)/psi. These results indicate that the backbone and side-chain structures of For-L-Ser-NH(2) have a strong influence on its chemical shifts.