波谱-研究生-2DNMR简介及应用.ppt

(二) 异核相关谱 异核相关谱—两种模式 ? X-detected 13C-1H COSY HETeronuclear CORrelation COLOC: COrrelation of LOng range Coupling Heteronuclear Proton Relay 1D and 2D INADEQUATE ? H-detected HMQC, HSQC, HMBC, H-detected (Inverse Mode)—反相模式 Low-gamma low-sensitivity X nuclei when limited amount of material is available, the direct detection of Carbon-13 can be almost impossible High-sensitive protons Basic idea: detection of 1H spectra during t2 - the detection time; the X chemical shift is detected during t1 - the evolution time. 1. HMQC (Heteronuclear Multiple Quantum Correlation) The HMQC experiment provides correlation between protons and their attached heteronuclei through the heteronuclear scalar coupling. 氢检测的异核多量子相关谱 HMQC是将信号的振幅及相位分别依13C化学位移及1H间的同核化学耦合信息调制，并通过直接检测调制后的1H信号，获得13C-1H化学位移相关数据。它提供的信息及谱图与1H-13C COSY 完全相同—得到的是直接相连的13C与1H之间的耦合关系，不能得到季碳的结构信息。 100 80 60 40 20 0 2 5 4 3 1 0 1H 13C C-H异核相关谱给出碳氢的偶合关系- 实例1: C-H异核相关谱给出碳氢的偶合关系-HMQC 实例2: 异核相关谱可通过观测碳(1H-13C Hetcor) 或观测氢 (HMQC, HSQC). 观测氢的实验也称做反相实验. 13C-1H HMQC of Sucrose in D2O 13C 1H HSQC: Heteronuclear Single Quantum Correlation HMQC实例: Each proton-carbon pair has a single crosspeak. 13C nuclei that have diasteriotopic protons have two correlations (some of these crosspeak pairs are boxed in the spectrum below). HMBC 2: HMBC (Heteronuclear Multiple Bond Correlation) The HMBC experiment detects long range coupling between proton and carbon (two or three bonds away) with great sensitivity. C2 C5 CO C1 HMBC实例: ? HMBC 可高灵敏度地检测到13C-1H远程耦合（2JCH，3JCH）, 因此可得到有关季碳的结构信息及被杂原子切断的1H耦合系统之间的结构信息。 三. Nomenclature PFG: 脉冲梯度场(Pulsed Field Gradients) GS: 梯度场选择(Gradient Selected) GRASP: 梯度增速光谱学(Gradient Accelerated Spectroscopy) GE: 梯度场增强(Gradient Enhanced) Recovery time: 梯度脉冲后,线圈恢复时间 (Settling time after a gradient pulse). 四.应用举例: 1. 一化合物的分子式为 C7H9NO2, 所有图谱如下,试推出结构. 活泼H 羰基 C 1 2 3 4 1 2 3 4 5 5 4 3 2 1 * * * * * * Lock Hold: Temporary int