Probing Structure and Dynamics in Advanced Molecular Materials by Solid State Nuclear Magnetic Resonance



Hughes, Ashlea
(2021) Probing Structure and Dynamics in Advanced Molecular Materials by Solid State Nuclear Magnetic Resonance. Doctor of Philosophy thesis, University of Liverpool.

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Abstract

Probing and determining the structure and dynamics of advanced molecular materials is crucial to aid our understanding of their properties. Solid state NMR is capabale of probing short-range order and dynamics. Therefore this analytical technique (often used in conjunction with computational studies) is able to provide structural characterisation at the atomic level as well as probing local order and therefore has great potential to study these motions. In this thesis, advanced solid state NMR approaches have been used to access the temperature dependence site-selective dynamics of guest-free and -adsorbed tubular covalent cages and pillar[n]arenes, accessing understanding of their flexibility behaviours, and determine the structures of a new class of amorphous paramagnetic hybrid perovskites glasses. Firstly, 2H static NMR spectra has identified tubular covalent cages as ultra-fast molecular rotors and smart materials capable of adsorbing iodine and its release upon the application of an external stimuli. Secondly, correlation times and proton detected local field NMR experiments found that the extruding ethoxy group of perethylated pillar[n]arenes has significant dynamics when compared to the dynamics associated within the core. Using these techniques we also show the strong dipolar coupling present between para-xylene and the EtP6 host, providing insights into the guest’s location inside the host. Finally, spectral analysis of paramagnetic hybrid perovskites was completed and NMR methods were able to confirm that the materials studied melt at low temperatures and can be quenched into a glass form. It is the dynamics and flexibility of these structures that controls the selectivity of molecules in the voids located in the frameworks and hence enable them to be used for molecular separation.

Item Type: Thesis (Doctor of Philosophy)
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 25 Jun 2021 10:20
Last Modified: 01 Sep 2022 07:38
DOI: 10.17638/03126763
Supervisors:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3126763