Application of HSQC to the measurement of homonuclear coupling constants,J(H,H)

Simova, Svetlana

doi:10.1002/(sici)1097-458x(199807)36:7<505::aid-omr300>3.0.co;2-h

Cited by 48 publications

(10 citation statements)

References 3 publications

(3 reference statements)

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“…Homodecoupling, as a means of suppressing scalar interactions for enhanced spectral resolution, has been recognized for several years. [1][2][3][4][5][6][7][8][9][10][11][12][13] Subsequent seminal developments of broadband homodecoupling techniques to achieve complete collapse of multiplets to pure-shift singlets include: Zangger-Sterk (ZS) decoupling scheme [12] and its refined variants for multidimensional NMR [14][15][16][17][18][19] that rely on spatially encoded excitation in the presence of sliceselective z-gradient pulse. On the other hand, 13 C-isotopefiltered bilinear rotational decoupling (BIRD) [20] based schemes are reported, which particularly eliminate strong coupling effects [21,22] and are also advantageous for obtaining fully decoupled pure-shift HSQC.…”

Section: Introductionmentioning

confidence: 99%

Real‐time homonuclear broadband and band‐selective decoupled pure‐shift ROESY

Kakita

Jagadeesh

2014

Magnetic Reson in Chemistry

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Unambiguous spectral assignments in (1)H solution-state NMR are central, for accurate structural elucidation of complex molecules, which is often hampered by signal overlap, primarily because of scalar coupling multiplets, even at typical high magnetic fields. The recent advances in homodecoupling methods have shown powerful means of achieving high resolution pure-shift (1)H spectra in 1D and also in 2D J-correlated experiments, by effectively collapsing the multiplet structures. The present work extends these decoupling strategies to through-space correlation experiments as well and describes two new pure-shift ROESY pulse schemes with homodecoupling during acquisition, viz., homodecoupled broadband (HOBB)-ROESY and homodecoupled band-selective (HOBS)-ROESY. Furthermore, the ROESY blocks suppress the undesired interferences of TOCSY cross peaks and other offsets. Despite the reduced signal sensitivity and prolonged experimental times, the HOBB-ROESY is particularly useful for molecules that exhibit an extensive scalar coupling network spread over the entire (1)H chemical shift range, such as natural/synthetic organic molecules. On the other hand, the HOBS-ROESY is useful for molecules that exhibit well-separated chemical shift regions such as peptides (NH, Hα and side-chain protons). The HOBS-ROESY sensitivities are comparable with the conventional ROESY, thereby saves the experimental time significantly. The power of these pure-shift ROESY sequences is demonstrated for two different organic molecules, wherein complex conventional ROE cross peaks are greatly simplified with high resolution and sensitivity. The enhanced resolution allows deriving possibly more numbers of ROEs with better accuracy, thereby facilitating superior means of structural characterization of medium-size molecules.

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Section: Introductionmentioning

confidence: 99%

Real‐time homonuclear broadband and band‐selective decoupled pure‐shift ROESY

Kakita

Jagadeesh

2014

Magnetic Reson in Chemistry

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“…Consequently, we felt that a better approach would be to use a coupled HSQC spectrum to separate the different proton multiplets along the 13 C axis (Reynolds et al, 1997a;Leon et al, 1998;Simova, 1998;Mazzola et al, 2011). This is preferable to using a coupled HMQC spectrum, since proton couplings appear along both 1 H and 13 C axes in HMQC spectra (Reynolds et al, 1997a), which would complicate the spectral interpretation.…”

Section: Resultsmentioning

confidence: 99%

The Use of Coupled HSQC Spectra to Aid in Stereochemical Assignments of Molecules with Severe Proton Spectral Overlap

Powder-George

Frank

Ramsewak

et al. 2011

Phytochemical Analysis

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“…The NMR spectra have been recorded on Bruker spectrometers (AV600II+, DMX 600, and DRX 250, Bruker Biospin GmbH, Rheinstetten, Germany ) at two different frequencies: 600.13 and 250.13 MHz for protons, 150.91 and 62.9 MHz for carbon, and 92.12 and 38.40 MHz for deuterium at room temperature. All experiments at the lower frequency spectrometer DRX 250 were recorded as nongradient versions using the Bruker pulse programs including 1 H, 13 C{ 1 H}, 13 C with gated 1 H decoupling, DEPT135, nongradient versions of NOESY, modified HSQC, HMBC, and selective DEPT experiments . The concentration of all isotropic solution samples was approximately 100 m m in the corresponding solvents as mentioned in the text.…”

Section: Methodsmentioning

confidence: 99%

“…12 and 38.40 MHz for deuterium at room temperature. All experiments at the lower frequency spectrometer DRX 250 were recorded as nongradient versions using the Bruker pulse programs including 1 H, 13 C{ 1 H}, 13 C with gated 1 H decoupling, DEPT135, nongradient versions of NOESY, modified HSQC, [65] HMBC, and selective DEPT experiments. [66,67] The concentration of all isotropic solution samples was approximately 100 mM in the corresponding solvents as mentioned in the text.…”

Section: Methodsmentioning

confidence: 99%

Configuration verification via RDCs on the example of a tetra‐substituted pyrrolidine ring

Tzvetkova

Luy

2012

Magnetic Reson in Chemistry

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The configurational analysis of organic compounds is an important application for high resolution NMR spectroscopy. In the present study, a tetra-substituted pyrrolidine with four chiral carbon atoms is analyzed using classical methods based on (3) J and NOE data in solution and compared and verified with recently introduced alternative approaches via residual dipolar couplings (RDCs) in two weak anisotropic alignment media. The molecule shows sufficient rigidity in the five-membered ring for the configurational characterization with the various techniques. However, the flexibility caused by the many freely rotating bonds potentially poses problems for the interpretation of data. It is shown that RDCs measured in poly-γ-benzyl-l-glutamate and a stretched polydimethylsiloxane gel provide useful information for the distinction of diastereomers, but the success varies with the data interpretation strategy used. Although a general improvement of corresponding correlation factors is observed when limiting data to a subset of dipolar couplings directly connected to the central ring, the distinction power is reduced because of the smaller number of RDCs available for potential model falsification. Singular value decomposition for fitting experimental RDCs is able to distinguish in most cases the correct from incorrect configurations, but the differences in correlation factors can be relatively small. Surprisingly, predicting RDCs using the rod model as implemented in PALES gives best results in distinguishing the eight possible diastereomers. It is also found that the use of proton-phosphorus and carbon-phosphorus RDCs helps with the configurational analysis of the model compound.

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Application of HSQC to the measurement of homonuclear coupling constants,J(H,H)

Cited by 48 publications

References 3 publications

Real‐time homonuclear broadband and band‐selective decoupled pure‐shift ROESY

Real‐time homonuclear broadband and band‐selective decoupled pure‐shift ROESY

The Use of Coupled HSQC Spectra to Aid in Stereochemical Assignments of Molecules with Severe Proton Spectral Overlap

Configuration verification via RDCs on the example of a tetra‐substituted pyrrolidine ring

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