Barile, Giuseppina ORCID: https://orcid.org/0000-0002-7149-7873
(2024)
An experimental and computational study of the effects of terminal group design in liquid crystal hosts and guest dyes.
PhD thesis, University of York.
Abstract
A combination of experimental and computational methods were used to develop an
understanding of the effects of bulky terminal groups on the promotion of smectic A phase
formation. This work used two series of liquid crystal hosts, the 4-n-alkoxy-4′
cyanobiphenyl (nOCB) and the 4-(t-Bu-n-alkoxy)-4′-cyanobiphenyl (t-Bu-nOCB) series,
which were studied separately and in guest-host mixtures containing 2,6-disubstituted
anthraquinone dyes with p-alkoxy-phenyl and p-t-Bu-alkoxy-phenyl substituents.
From the studies of the hosts alone, it was found that the bulky terminal group promoted the
formation of a smectic A phase and resulted in more ordered layers in the phase, relative to
analogous molecules without the bulky group. The t-Bu-nOCB series also showed larger
layer spacings than the nOCB series, which could be attributed to a decrease in the
interdigitation of the t-Bu-alkoxy chains in order to accommodate the bulky terminal groups.
It was found that molecular dynamics simulations provided useful insight into the trends
observed for the two series, and in particular for the layer spacing measured experimentally
by X-ray diffraction studies.
In the guest-host studies, TD-DFT calculations showed that there was only a small angle
between the transition dipole moment and the molecular long axis for both series of dyes.
The DFT calculations and molecular dynamics simulations provided insight into a wide
range of guest-host mixtures, and were able to be used predictively to select which guest
host mixtures to study experimentally. Polarised UV-visible absorption measurements were
used to determine the dichroic ratios of some aligned guest-host mixtures experimentally.
All mixtures showed high dichroic ratios and dye orientational order, giving possible
mixtures for guest-host device application
Metadata
Supervisors: | Moore, John and Cowling, Stephen |
---|---|
Awarding institution: | University of York |
Academic Units: | The University of York > Chemistry (York) |
Depositing User: | Ms Giuseppina Barile |
Date Deposited: | 17 May 2024 14:31 |
Last Modified: | 17 May 2024 14:31 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:34898 |
Download
Examined Thesis (PDF)
Filename: Barile_202017646_CorrectedThesisClean.pdf
Licence:
This work is licensed under a Creative Commons Attribution NonCommercial NoDerivatives 4.0 International License
Export
Statistics
You do not need to contact us to get a copy of this thesis. Please use the 'Download' link(s) above to get a copy.
You can contact us about this thesis. If you need to make a general enquiry, please see the Contact us page.