Anisotropy of molecular reorientation and geometrical information as determined from short and long range 13C-1H spin cross-relaxation rates

Mutzenhardt, Pierre; WALKER, O.; Canet, Daniel; Haloui, Ezzeddine; FURO, I.

doi:10.1080/00268979809482349

Cited by 7 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[15] Here, we have demonstrated that, even if sensitivity is lacking, a very simple selective experiment can lead to the desired information provided that mixing times maximizing responses are chosen, and that signal intensities are processed by means of the Solomon equations. This implies, however, to have been determined from independent measurements, the proton and carbon specific relaxation rates.…”

Section: Resultsmentioning

confidence: 97%

Selective HOESY experiments for stereochemical determinations

Yemloul

Bouguet‐Bonnet

Ba³

et al. 2008

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

Heteronuclear Overhauser effect spectroscopy (HOESY) is a powerful method for tracking geometrical proximities between two heteronuclei (for instance, (1)H and (13)C, as this will be the case here). The method is based on cross-relaxation arising from dipolar interactions. Sensitivity permitting, it is applied in the 2D mode yielding all spatial correlations in a single experiment. Whenever sensitivity is not sufficient, it can be applied in the one-dimensional mode by selectively inverting one particular proton. In that case, it yields, from the carbon-13 spectrum, remote spatial correlations. The method has been employed here for the discrimination between two possible E or Z isomers in a medium-size molecule.

show abstract

Section: Resultsmentioning

confidence: 97%

Selective HOESY experiments for stereochemical determinations

Yemloul

Bouguet‐Bonnet

Ba³

et al. 2008

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…Temperature was thus carefully adjusted by means of the temperature proton chemical shift dependence of methanol, 22 the same calibration sample being used for all the spectrometers involved in this study. Cross-relaxation rates were measured on a Bruker Avance spectrometer operating at 9.4 T with an inverse 1 H/ 13 C probe and using a strategy described elsewhere 7 which requires 1D and 2D HOESY 23 experiments. Proton decoupling during carbon-13 chemical shift evolution was suppressed in the 2D HOESY experiment in order to access to cross-relaxation rates between chemically equivalent sites in the molecule.…”

Section: Methodsmentioning

confidence: 99%

Determination of Carbon-13 Chemical Shielding Tensor in the Liquid State by Combining NMR Relaxation Experiments and Quantum Chemical Calculations

et al. 2002

Self Cite

View full text Add to dashboard Cite

Based on multifield NMR relaxation measurements and quantum chemistry calculations, a strategy aiming at the determination of the chemical shielding tensor (CST) in the liquid state is described. Brownian motions in the liquid state restrict the direct observation of CST to a third of its trace (isotropic shift), and even if CST can be probed indirectly through some spin relaxation rates (specific longitudinal relaxation rates, dipolar chemical shift anisotropy (CSA) cross-correlation rates), an insufficient number of experimental parameters prevents its complete determination. This lack of information can be compensated by using quantum chemical calculations so as to obtain the molecular CST orientation even if a relatively modest level of computation is used. As relaxation parameters involve a dynamic part, a prerequisite is the determination of the molecular anisotropic reorientation which can be obtained independently from dipolar cross-relaxation rates. A polycyclic molecule exhibiting a well-characterized anisotropic reorientation serves as an example for such a study, and some (but not all) carbon-13 chemical shielding tensors can be accurately determined. A comparison with solid-state NMR data and numerous chemical quantum calculations are presented.

show abstract

“…Moreover, this methodology was used successfully to extract structural and dynamical information from medium-sized molecules. 17,18 However, due to 13 C detection, this kind of experiment suffers from low sensitivity and requires (i) a highly concentrated sample or/and (ii) a substantial number of scans to ensure that some interactions are indeed accurately detected. (˛ x and (2˛ y are long radio-frequency pulses at high power level (1.5 ms and 3 ms respectively) which are placed at the beginning of the mixing time to saturate all 13 C magnetization.…”

Section: Direct Detected Hoesy Experimentsmentioning

confidence: 99%

Heteronuclear Overhauser experiments for symmetric molecules

Walker¹,

Mutzenhardt²,

Canet³

2003

Magnetic Reson in Chemistry

Self Cite

View full text Add to dashboard Cite

The nuclear Overhauser effect (NOE) arises from dipolar interactions between magnetic moments associated with nuclear spins and it has become a powerful tool to extract relevant pieces of structural information about small molecules, as well as in molecules of biological interest. As a consequence, accurate NOE measurement is a very crucial issue. Here, we present a comparison between direct and a new inverse HOESY experiment aimed at the detection of heteronuclear NOE between 1 H and 13 C, which is particularly well suited for symmetric compounds. It transpires that directly detected data are more suitable for quantitative assessment even if they suffer from lower sensitivity, whereas inverse detection is quite appropriate for a quick and qualitative assessment. In the latter experiment, unwanted cross-correlation effects may hide valuable NOE data (cross-relaxation), this drawback can be circumvented by a slight modification of the pulse sequence.

show abstract

Anisotropy of molecular reorientation and geometrical information as determined from short and long range 13C-1H spin cross-relaxation rates

Cited by 7 publications

References 0 publications

Selective HOESY experiments for stereochemical determinations

Selective HOESY experiments for stereochemical determinations

Determination of Carbon-13 Chemical Shielding Tensor in the Liquid State by Combining NMR Relaxation Experiments and Quantum Chemical Calculations

Heteronuclear Overhauser experiments for symmetric molecules

Contact Info

Product

Resources

About