1. Asynchronising five-fold symmetry sequence for better homonuclear polarisation transfer in magic-angle-spinning solid-state NMR.
- Author
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Arunachalam V, Sharma K, Mote KR, and Madhu PK
- Abstract
Recoupling, decoupling, and multidimensional correlation experiments in magic-angle-spinning (MAS) solid-state NMR can be designed by exploiting the symmetry of internal spin interactions. One such scheme, namely, C5
2 1 , and its supercycled version SPC52 1 , notated as a five-fold symmetry sequence, is widely used for double-quantum dipole-dipole recoupling. Such schemes are generally rotor synchronised by design. We demonstrate an asynchronous implementation of the SPC52 1 sequence leading to higher double-quantum homonuclear polarisation transfer efficiency compared to the normal synchronous implementation. Rotor-synchronisation is broken in two different ways: lengthening the duration of one of the pulses, denoted as pulse-width variation (PWV), and mismatching the MAS frequency denoted as MAS variation (MASV). The application of this asynchronous sequence is shown on three different samples, namely, U-13 C-alanine and 1,4-13 C-labelled ammonium phthalate which include13 Cα -13 Cβ ,13 Cα -13 Co , and13 Co -13 Co spin systems, and adenosine 5'- triphosphate disodium salt trihydrate (ATP⋅3H2 O). We show that the asynchronous version performs better for spin pairs with small dipole-dipole couplings and large chemical-shift anisotropies, for example,13 Co -13 Co . Simulations and experiments are shown to corroborate the results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)- Published
- 2023
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