Relaxation Editing Using Long-Lived States and Coherences for Analysis of Mixtures

Abstract

Nuclear magnetic resonance (NMR) is a powerful tool for structural and dynamical studies of molecules. Although widely applicable, the search for novel spectral editing methods that facilitate spectral assignment of peaks in high-resolution NMR is highly desirable. Earlier, the sensitivity of lifetime of spin states (spin-lattice relaxation time, T1) and coherences (spin-spin relaxation time, T2) to the immediate environment was utilized for spectral editing in solution NMR. Long-lived states (LLS) and coherences (LLCs) were recently uncovered to have longer and more domain sensitive lifetime than other type of states and coherences. Herein, this longevity and increased sensitivity of LLS and LLC lifetime is utilized for more enhanced dispersion in relaxation editing in NMR. The generality of the method as a powerful tool in spectral editing is confirmed with molecules containing a mixture of strongly and weakly coupled spin systems and finally with metabolomic mixture. Extension to insensitive nuclei enhanced by polarization transfer (INEPT), correlation spectroscopy (COSY), and heteronuclear single quantum coherence (HSQC) are also demonstrated.

Nuclear Spin Singlet Order Selection by Adiabatically Ramped RF Fields

“…For assessing the application range of the SOS-filter, its performance will be compared with that of the alternative methods used for filtering LLSs in macromolecules and wiping out residual signals. Such methods have been proposed and exploited in refs , , ; more recently, DeVience et al proposed the so-called SUCCESS pulse sequence. All of these techniques use the long-lived nature of the singlet order.…”

Chiral Recognition by Dissolution DNP NMR Spectroscopy of 13C-Labeled dl-Methionine

“…This condition makes difficult (i) the shimming process previous the acquisition and (ii) a robust reproducible transfer of the dissolution to the NMR tube, which affects, respectively, the enantioresolution E of the split peaks and the global reproducibility and robustness of the method. d-DNP NMR technology is advancing very fast and last progresses, especially those focused on preserving the enhanced magnetization (e.g., long-lived states) − and the use of specially designed sample injectors, will help overcome the aforementioned limitations, allowing a broader development of the described methodology for chiral recognition studies.…”

Perspective on long-lived nuclear spin states

“…An improved implementation of this concept was described by Ivanov and co-workers, using a magnetisation to singlet conversion pulse sequence based on an adiabatic sweep, which led to an improved contrast between the selected singlet-forming 1 H pair and the suppressed background [37,38]. Singh et al have proposed to use singlet relaxation as a tool for spectral editing in mixtures [39].…”