25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Boosting the NMR characterization of small- to medium-sized molecules

28 Aug 2019, 10:30
35m
Lecture Hall B (Henry Ford Building)

Lecture Hall B

Henry Ford Building

Invited talk Small molecules Small Molecules

Speaker

Prof. Katalin E. Kövér (University of Debrecen)

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.

  1. Koos, MRM, Kummerlöwe, G, Kaltschnee, L, Thiele, CM, Luy, B,
    Angew. Chem., Int. Ed., 55, 7655-7659, 2016
  2. Gyöngyösi, T, Timári, I, Haller, J, Koos, MRM, Luy, B, Kövér, KE, ChemPlusChem, 83, 53-60, 2018
  3. Gyöngyösi, T, Nagy TM, Kövér, KE, Sørensen, OW,
    Chem. Commun., 54, 9781-9784, 2018

Primary author

Prof. Katalin E. Kövér (University of Debrecen)

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