Nuclear magnetic resonance multi-dimensional spectrum method for measuring hydrogen-hydrogen coupling constant of specific hydrogen nucleus

Abstract

The invention provides a nuclear magnetic resonance multi-dimensional spectrum method for measuring the hydrogen-hydrogen coupling constant of a specific hydrogen nucleus. The nuclear magnetic resonance multi-dimensional spectrum method comprises: applying a selective 90 DEG soft pulse while applying a Z-direction magnetic field gradient; applying a perfect echo module, and applying Z-direction magnetic field gradients with the same strength and the same direction on both sides of the selective 180 DEG soft pulse of the perfect echo; adding the 180 DEG soft pulse of an S nucleus after the first t1 / 2 evolution time in the second echo of the perfect echo so as to retain the J-coupling information of the S nucleus; adding the 180 DEG soft pulse of the S nucleus after the second t1 / 2 to compensate phase distortion; respectively applying the 180 DEG soft pulse of the selective S nucleus before the two t1 / 2 evolution times in the second echo so as to obtain a R type sequence corresponding toa N type sequence; and finally carrying out addition on a N type spectrum and a R type spectrum inverted along indirect dimension to obtain a phase-sensitive two-dimensional spectrum, and obtaining the corresponding J-coupling constant by measuring from the splitting of the peak in the indirect dimension.

Description

technical field [0001] The invention relates to a nuclear magnetic resonance multidimensional spectrum method, in particular to a nuclear magnetic resonance multidimensional spectrum method capable of accurately measuring the hydrogen-hydrogen J coupling constant of a specific hydrogen nucleus in a molecule. Background technique [0002] The interaction between spin nuclei and spin nuclei is a main information in the NMR spectrum, which reflects the information of organic structure, especially the information of three-dimensional structure chemistry. Among them, the triple bond J coupling between hydrogen and hydrogen is widely used in the study of molecular conformation because its coupling constant is related to the dihedral angle formed by the triple bond. However, the coupling constant between hydrogen and hydrogen is often difficult to measure from a simple one-dimensional hydrogen spectrum, because the narrow chemical shift distribution, complex split peak mode and lar...

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Problems solved by technology

However, this method is based on the ZS decoupling module, so the strength of the signal is affected by the bandwidth of the selective pulse

The resulting spectrograms often have extremely weak signal strength, resulting in low resolution of the spectrograms and affecting the measurement of the J coupling constant.

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