Novel CLIP-COSY based homo- and heteronuclear correlation experiments are reported for the rapid, semi-automated NMR assignment of small to medium-sized molecules. The homonuclear CLIP-COSY and corresponding relayed experiments employ the perfect-echo based mixing sequence for in-phase coherence transfer between directly and/or indirectly coupled proton spins. The combined analysis of the resulting CLIP-COSY and relayed spectra made it possible to easily track down, layer by layer, the proton-proton connectivity network. In larger molecules the narrow chemical shift range of protons may, however, compromise the efficacy of the homonuclear correlation based assignment strategy. To overcome this limitation, an HSQC variant of the CLIP-COSY experiment has now been devised. Combined treatment of HSQC-CLIP-COSY (relayed) and standard HSQC spectra facilitates simultaneous and semi-automatic assignment of 1 H and 13 C resonances of medium-sized molecules, such as pentasaccharides. The recently introduced PSYCHE broadband homonuclear decoupling scheme has been also implemented into the devised homo- and heteronuclear CLIP-COSY based experiments, resulting in fully decoupled high-resolution pure-shift correlation spectra.

中文翻译：

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通过干净的同相相关性实验提高碳水化合物的NMR分配。

据报道，基于新型CLIP-COSY的同核和异核相关实验可对中小型分子进行快速，半自动NMR核对。同核CLIP-COSY和相应的中继实验采用基于完美回波的混合序列，在直接和/或间接耦合的质子自旋之间进行相干相干转移。对生成的CLIP-COSY和中继光谱的综合分析使轻松逐层跟踪质子-质子连接网络成为可能。然而，在较大的分子中，质子的化学位移范围窄，可能会损害基于同核相关性的分配策略的功效。为克服此限制，现已设计出CLIP-COSY实验的HSQC变体。HSQC-CLIP-COSY（中继）和标准HSQC光谱的组合处理有助于同时和半自动分配中等大小的分子（如五糖）的1 H和13 C共振。最近引入的PSYCHE宽带同核去耦方案也已实施到基于同质和异核CLIP-COSY的实验中，从而产生了完全解耦的高分辨率纯位移相关谱。