Tognetti, Jacqueline (2022) Advances in 1H-detected solid-state NMR spectroscopy. PhD thesis, University of Warwick.

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Abstract

The overall aim of this thesis is to develop experimental methods to improve the acquisition of proton detected solid-state NMR experiments at fast (≥ 60 kHz) magic angle spinning (MAS). 1H-detection at fast MAS is often used to enhance the signal of natural abundance rare and low gamma nuclei. However, strong 1H-1H homonuclear dipolar couplings negatively impact the quality of the spectra and even 60-100 kHz MAS is not sufficient to average them out completely. Consequently, even in that spinning regime it is worthwhile to improve the proton resolution and coherence lifetimes by combining with 1H homonuclear decoupling. In the first part of the thesis, supercycled Phase Modulated Lee-Goldburg (PMLG) homonuclear decoupling was evaluated in its windowed and windowless form at 60 kHz MAS, for nutation frequencies ≤ 100 kHz. The optimized decoupling scheme was then employed on the proton channel during the INEPT transfer for detecting the first natural abundance 2D 15N-1H CP-Refocused INEPT correlation experiment at 60 kHz MAS.

In the second part of the thesis, two methods for improving relaxation measurements via 1H detected experiments at 100 kHz MAS are presented. Relaxation rates are important probes of molecular motions, but their measurements are typically time consuming. To partially alleviate this problem, we have developed approaches to obtain multiple measurements of relaxation rates in a single experiment. In the first of the presented methods 13CO and 15N relaxation rates are measured in a single experiment, sharing the same recycle delay, and, in the case of spin-lattice relaxation, also the relaxation delays. In the second approach, instead, relaxation delays on multiple nuclei of the protein backbone (15N, 13CO and 13Cα) can be fitted into the longest relaxation delays. This approach enables the measurement of multiple rates in the same nested experiment in a fraction of the time necessary for separate experiments.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QA Mathematics Q Science > QC Physics Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Solid state physics, Nuclear magnetic resonance spectroscopy, Nuclear spin, Relaxation (Nuclear physics), Decoupling (Mathematics)
Official Date:	March 2022
Dates:	Date Event March 2022 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry ; Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Brown, Steven P. ; Lewandowski, Józef R.
Format of File:	pdf
Extent:	vii, 123 pages : illustrations (colour), charts (colour)
Language:	eng

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