Symmetry principles in the nuclear magnetic resonance of spinning solids: Heteronuclear recoupling by generalized Hartmann–Hahn sequences

Abstract

General symmetry principles for rotor-synchronized pulse sequences in magic-angle spinning solid-state nuclear magnetic resonance are presented. The theory of symmetry-based pulse sequences using pulse elements is presented for the first time. The symmetry theory is extended to the case of generalized Hartmann-Hahn sequences, in which rotor-synchronized rf irradiation is applied simultaneously to two isotopic spin species. The symmetry principles lead to heteronuclear selection rules. The symmetry theory is used to design pulse sequences which implement heteronuclear dipolar recoupling at the same time as decoupling homonuclear spin-spin interactions, and which also suppress chemical shift anisotropies. A number of specific pulse sequences based on these principles are listed. Experimental demonstrations are given of heteronuclear two-dimensional correlation spectroscopy, heteronuclear multiple-quantum spectroscopy, and the estimation of internuclear dipolar couplings.

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

“…There are many different types of pulse sequences achieving recoupling of heteronuclear dipolar couplings. [28][29][30] A detailed overview of the different properties of a selection of heteronuclear recoupling sequences can be found in ref 31. In the following, the most prominent sequences are briefly presented and discussed in the context of estimating 17 O-1 H heteronuclear dipolar couplings.…”

“…These sequences achieve heteronuclear longitudinal two-spin-order (I z S z ) recoupling, hence not suffering from dipolar truncation, while decoupling the I-spin homonuclear dipolar couplings. 31,30 The heteronuclear longitudinal two-spin-order recoupling sequences are demonstrated by numerical simulations and by experimentally estimating the 17 In this contribution we combine the approaches described above to develop a comprehensive methodology to study hydrogen bonding in biological systems through 17 O and 17 O-1 H NMR.…”

Symmetry‐Based Pulse Sequences in Magic‐Angle Spinning Solid‐State NMR

“…45, 60 it is shown that these symmetry properties lead to selection rules on the average Hamiltonian terms:…”

“…45,60 A summary of the spin interaction components, in the case of exact magic-angle spinning, is given in Table 2.…”

“…60 For the sake of concreteness, consider a C7 1 2 sequence based upon the cyclic element C = 270 0 180 180 (13) where the pulses are contiguous (no gaps in between). The rf field amplitude is chosen so that the entire sequence of 21 pulses fits exactly into two complete rotational periods of the sample.…”