Center of Biomedical Magnetic Resonance, SGPGIMS Campus, Raebareli Road, Lucknow 226 014, India.
J Magn Reson. 2013 Sep;234:67-74. doi: 10.1016/j.jmr.2013.06.004. Epub 2013 Jun 19.
Homonuclear (1)H-(1)H J-modulation leads to J-multiplets in F1 dimension of 2D (1)H-(13)C HMQC spectra. This hampers unambiguous signal assignment for overcrowded (13)C spectra. Broadband homonuclear decoupling has been achieved in the indirect t1 evolution period by incorporating blocks of perfect echo. This method of perfect echo HMQC demonstrates better resolution and sensitivity than conventional HMQC spectra. The results on Cyclosporine demonstrate that the method is very efficient for refocusing geminal couplings in weakly coupled -(13)CH2 groups. Partial refocusing of vicinal couplings is also observed for -(13)CH and -(13)CH3 groups. Interpretation of the result based on product operator formalism is also given. Comparison of pe-HMQC, HMQC and HSQC reveals that the F1 linewidth of pe-HMQC is much narrower than HMQC and very close to that of HSQC for CH2 groups.
同核 (1)H-(1)H J 调制导致 2D (1)H-(13)C HMQC 谱中 F1 维度的 J 多重峰。这给拥挤的 (13)C 谱的信号分配带来了困难。通过在间接 t1 演化期间加入完美回波块,实现了宽带同核去耦。与传统的 HMQC 谱相比,这种完美回波 HMQC 方法具有更好的分辨率和灵敏度。环孢菌素的结果表明,该方法对于重新聚焦弱耦合 -(13)CH2 基团中的偕偶合非常有效。还观察到 -(13)CH 和 -(13)CH3 基团的邻偶合的部分聚焦。还基于乘积算符形式给出了结果的解释。pe-HMQC、HMQC 和 HSQC 的比较表明,pe-HMQC 的 F1 线宽比 HMQC 窄得多,对于 CH2 基团,与 HSQC 非常接近。