Signal enhancement of NMR spectra of half-integer quadrupolar nuclei in solids using hyperbolic secant pulses

Siegel, Renée; Nakashima, Thomas T.; Wasylishen, Roderick E.

doi:10.1016/j.cplett.2004.03.047

Cited by 114 publications

(127 citation statements)

References 23 publications

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“…Various sensitivity enhancement techniques are available for improving the signal-to-noise ratio of spectra of stationary samples and samples undergoing MAS, such as the quadrupolar-Carr-Purcell-Meiboom-Gill (QCPMG) sequence, 152 double-frequency sweeps (DFS), 153 rotorassisted population transfers (RAPT), 154,155 hyperbolic secant pulses, 156 or combinations thereof. 157 We refer the reader to the recent reviews by Wasylishen and coworkers on these topics.…”

Section: Powdered Samplesmentioning

confidence: 99%

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Bryce

Sward

2006

Magn. Reson. Chem.

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Section: Powdered Samplesmentioning

confidence: 99%

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Bryce

Sward

2006

Magn. Reson. Chem.

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“…The starting time point of the recoupling sequence is given by t 0 , and R RL 0 denotes the initial position of the rotor at that time point. [A 22 Λ ] R is the space component m ) 2 of the interaction tensor Λ with rank l ) 2, written in the rotor-fixed frame. The component in the rotor-fixed frame is obtained by transforming it from the principal axis system as follows: …”

Section: Symmetry-based Heteronuclear Longitudinal Two-spin-order Dipmentioning

confidence: 99%

Sensitivity Enhancement and Heteronuclear Distance Measurements in Biological ¹⁷O Solid-State NMR

Brinkmann

Kentgens

2006

J. Phys. Chem. B

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In this contribution we present a comprehensive approach to study hydrogen bonding in biological and biomimetic systems through 17 O and 17 O-1 H solid-state NMR combined with density functional theory calculations of 17 O and 1 H NMR parameters. We explore the signal enhancement of 17 O in L-tyrosine‚HCl using repetitive double-frequency swept radio frequency pulses in solid-state NMR. The technique is compatible with high magnetic fields and fast magic-angle spinning of the sample. A maximum enhancement by a factor of 4.3 is obtained in the signal-to-noise ratio of the selectively excited 17 O central transition in a powdered sample of 17 O η -L-tyrosine‚HCl at an external field of 14.1 T and a spinning frequency of 25 kHz. As little as 128 transients lead to meaningful 17 O spectra of the same sample at an external field of 18.8 T and a spinning frequency of 50 kHz. Furthermore we employed supercycled symmetry-based pulse sequences on the protons to achieve heteronuclear longitudinal two-spin-order (I z S z ) recoupling to determine 17 O-1 H distances. These sequences recouple the heteronuclear dipolar 17 O-1 H couplings, where dipolar truncation is absent, while decoupling the homonuclear proton dipolar interactions. They can be applied at fast magic-angle-spinning frequencies up and beyond 50 kHz and are very robust with respect to 17 O quadrupolar couplings and both 17O and 1 H chemical shift anisotropies, which makes them suitable for the use at high external magnetic fields. The method is demonstrated by determining the 17 O η -1 H distance in L-tyrosine‚HCl at a spinning frequency of 50 kHz and an external field of 18.8 T.

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“…For example, Stebbins et al have described applications of 18.8 and 21.1 T solid-state 27 Al, 17 O, 39 K, and 35 Cl NMR spectroscopy to study oxide materials. [1][2][3] Gan et al used magnetic fields as high as 40 T to achieve chemical shift resolution between four different aluminum environments in aluminoborate.…”

Section: Introductionmentioning

confidence: 99%

Chlorine-35/37 NMR Spectroscopy of Solid Amino Acid Hydrochlorides: Refinement of Hydrogen-Bonded Proton Positions Using Experiment and Theory

2006

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Trends in the chlorine chemical shift (CS) tensors of amino acid hydrochlorides are investigated in the context of new data obtained at 21.1 T and extensive quantum chemical calculations. The analysis of chlorine-35/37 NMR spectra of solid L-tryptophan hydrochloride obtained at two magnetic field strengths yields the chlorine electric field gradient (EFG) and CS tensors, and their relative orientations. The chlorine CS tensor is also determined for the first time for DL-arginine hydrochloride monohydrate. The drastic influence of 1 H decoupling at 21.1 T on the spectral features of salts with particularly small 35 Cl quadrupolar coupling constants (C Q ) is demonstrated. The chlorine CS tensor spans (Ω) of hydrochloride salts of hydrophobic amino acids are found to be larger than those for salts of hydrophilic amino acids. A new combined experimental-theoretical procedure is described in which quantum chemical geometry optimizations of hydrogen-bonded proton positions around the chloride ions in a series of amino acid hydrochlorides are cross-validated against the experimental chlorine EFG and CS tensor data. The conclusion is reached that the relatively computationally inexpensive B3LYP/ 3-21G* method provides proton positions which are suitable for subsequent higher-level calculations of the chlorine EFG tensors. The computed value of Ω is less sensitive to the proton positions. Following this cross-validation procedure, |C Q ( 35 Cl)| is generally predicted within 15% of the experimental value for a range of HCl salts. The results suggest the applicability of chlorine NMR interaction tensors in the refinement of proton positions in structurally similar compounds, e.g., chloride ion channels, for which neutron diffraction data are unavailable. IntroductionThe availability of high-field solid-state nuclear magnetic resonance (NMR) spectrometers, e.g., those with 1 H resonance frequencies of 800 MHz, 900 MHz, and above, has created new opportunities for the study of quadrupolar nuclei (I > 1/ 2) with low resonance frequencies or large quadrupole moments, and for nuclei with both of these properties. For example, Stebbins et al. have described applications of 18.8 and 21.1 T solid-state 27 Al, 17 O, 39 K, and 35 Cl NMR spectroscopy to study oxide materials. 1-3 Gan et al. used magnetic fields as high as 40 T to achieve chemical shift resolution between four different aluminum environments in aluminoborate. 4 Ellis and colleagues have applied high-field 67 Zn NMR at low temperature to study zinc binding environments of biological relevance. 5,6,7,8 Magicangle-spinning (MAS) NMR in a magnetic field of 19.6 T has been applied by Wu and co-workers to detect potassium cations in guanine-quadruplex structures 9 as well as to explore cation-π interactions in alkali metal tetraphenylborates. 10 Cross and coworkers have demonstrated the utility of 17 O solid-state NMR at 21.1 T for characterizing the ion channel gramicidin. 11,12 The major reason that higher fields are so beneficial for the study of quadrupolar nuclei in ...

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Signal enhancement of NMR spectra of half-integer quadrupolar nuclei in solids using hyperbolic secant pulses

Cited by 114 publications

References 23 publications

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Sensitivity Enhancement and Heteronuclear Distance Measurements in Biological ¹⁷O Solid-State NMR

Chlorine-35/37 NMR Spectroscopy of Solid Amino Acid Hydrochlorides: Refinement of Hydrogen-Bonded Proton Positions Using Experiment and Theory

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Signal enhancement of NMR spectra of half-integer quadrupolar nuclei in solids using hyperbolic secant pulses

Cited by 114 publications

References 23 publications

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127

Sensitivity Enhancement and Heteronuclear Distance Measurements in Biological 17O Solid-State NMR

Chlorine-35/37 NMR Spectroscopy of Solid Amino Acid Hydrochlorides: Refinement of Hydrogen-Bonded Proton Positions Using Experiment and Theory

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Sensitivity Enhancement and Heteronuclear Distance Measurements in Biological ¹⁷O Solid-State NMR