Speaker
Description
The recently introduced CLIP-COSY[1] experiment providing homonuclear correlation spectrum with high quality clean in-phase multiplets expedites the assignment of scalar coupled proton spin network, aiding the structure elucidation of small- and medium-sized molecules. The resolution of COSY spectra is, however, limited by the inherently small chemical shift dispersion of proton resonances.
Last year we devised HSQC-variant of the CLIP-COSY experiment[2] for enhancing the resolving power of the method by utilizing the increased chemical shift range of heteronuclei. Herein, it will be demonstrated that the performance of the original HSQC-CLIP-COSY experiment can be further boosted with incorporation of heteronuclear spin echo block(s) in the pulse sequence, allowing phase-editing of crosspeaks of different types. The edited HSQC-CLIP-COSY experiments providing well-resolved spectra have great promise, enabling straightforward NMR assignments for carbohydrates and peptides and for other types of molecules.
The applicability of the CLIP-COSY approach can be extended for binding studies using a combined STD-CLIP-COSY(relayed) experiment. The resulting well-resolved, high quality 2D spectrum makes feasible to separate overlapping signals of 1D STD, allowing quantitative assessment of binding.
In small-molecule NMR there has always been a need for an experiment to distinguish between two- and three-bond correlations for quaternary 13C-s in a sensitive and reliable way. Last year we introduced a simple, non-selective experiment, SEA XLOC[3], which is capable to distinguish these correlations in a novel way and is applicable for all 13C multiplicities.
In the talk the scope and limitations of these experiments will be illustrated by applications to spins systems of varying complexity.
- Koos, MRM, Kummerlöwe, G, Kaltschnee, L, Thiele, CM, Luy, B,
Angew. Chem., Int. Ed., 55, 7655-7659, 2016 - Gyöngyösi, T, Timári, I, Haller, J, Koos, MRM, Luy, B, Kövér, KE, ChemPlusChem, 83, 53-60, 2018
- Gyöngyösi, T, Nagy TM, Kövér, KE, Sørensen, OW,
Chem. Commun., 54, 9781-9784, 2018