There is a significant reliance on small-angle X-ray scattering (SAXS) to determine the molecular organisation in liquid crystal (LC) phases, yet in reality the available information content is low and molecular-level detail is lacking. Quenching samples cryogenically and studying them by conventional transmission electron microscopy (TEM) can give additional levels of detail. But real, molecular-level detail is simply not available and in many LCs phases with complex 2D or (in some cases) 3D organisation, it remains difficult to understand how they are organised.
Electron cryo-microscopy offers the opportunity to 'see' that molecular-level detail and some very basic proof-of-concept studies have shown that, in an instrument designed for the study of biochemical materials, relatively simple modifications allow the study of LCs. The project therefore seeks to study some of the more complex liquid crystal phases where structural detail is lacking. These can be solvent-free (thermotropic) or solvent-based (lyotropic) systems and will be based on non-polymeric materials. This matters because LC phases are incredible examples of the very large macroscopic effects that can arise from otherwise minor changes at molecular level. Detailed understanding of how this works at the molecular level will sharpen further how these structure/property relationships can be deployed.
One early avenue of investigation are the families of cubic phases. Their structure can be described at high level quite well by various topological approaches, but exactly how this works at the molecular level requires elucidation. For example, how do we understand the apparent contradiction of chiral cubic phases formed from achiral molecules within which there is spontaneous symmetry breaking? This is but one of a series of fascinating problems lined up to be studied.
It will be necessary to prepare the materials that will be used for study and, while this will in almost all cases follow published routes, being able to prepare a wide range of highly pure materials will develop high levels of synthetic ability. The project will then require the student to become an expert operator of the Department's 200 kV Glacios electron cryo-microscope; remarkably for a cryo-microscope this is equipped to perform all three TEM imaging modalities: phase-contrast, scanning-TEM, and electron diffraction (microED).
The use of electron cryo microscopy in soft matter systems is in its infancy compared to its application in biological macromolecules and so far as we are aware, there are no studies at all at the level of detail we propose. This a real chance to be in at the beginning of something.
The project includes: synthetic chemistry in which area the student will gain significant expertise, complemented by gaining expertise in the normal methods of chemical characterisation (NMR spectroscopy, mass spectrometry, single-crystal X-ray analysis); liquid crystal characterisation using optical microscopy, calorimetry and small-angle X-ray scattering (SAXS); sample preparation learning and then further developing methods of sample preparation and cryogenic processing; instrument operation in order to get the best data sets from the samples; data processing using the software packages to get the most detailed pictures possible. All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/cdts/
The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/.
For more information about the project, click on the supervisor's name above to email the supervisor. For more information about the application process or funding, please click on email institution
This PhD will formally start on 1 October 2022. Induction activities may start a few days earlier.
To apply for this project, submit an online PhD in Chemistry application:
You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject.