Synthesis and properties of advanced chiral and racemic multifunctional molecular materials

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Rusbridge, EK, 2024. Synthesis and properties of advanced chiral and racemic multifunctional molecular materials. PhD, Nottingham Trent University.

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Abstract

Superconductivity is one of the most interesting phenomena of our time. First observed in 1911, materials possessing this property have the ability to conduct large electrical currents with zero resistance indefinitely.1 As a result of their powerful magnetic fields, superconducting materials are ideal for use in power transmission cables, superfast transport, as well as medical applications like that of MRI (magnetic resonance imaging). Superconductors have the ability to revolutionise vehicular and energy transport across the world. The main drawback for materials of this type is that they require expensive cryogenic cooling with liquid nitrogen or liquid helium to activate this superconducting state. Since the origin of high-temperature superconductivity and the ideal conditions required for a material to enter this state are not yet fully understood, this project aims to aid in providing theoretical information to allow explanation of this strange phenomenon. In this, a range of materials will be synthesised which possess both (super)conducting properties, as well as chirality; a combination that is not observed in nature, and in some cases, magnetism to yield a property trifecta. In doing so, it may be possible to understand the mechanisms of both superconductivity and eMChA (electrical magnetochiral anisotropy).

Three novel types of materials have been studied during this body of work, with particular focus on the first and second, whereby the third is included as a result of resistivity measurements performed by the author on materials synthesised by others within the research group. The first syntheses were based upon functionalisation of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) to yield novel donors with varying chiral sidechains, following the published work by the Martin research group very recently.2,3 A series of eight novel unsymmetrically substituted enantiopure donors have been realised based upon this previously published research, which may now be employed in the synthesis of novel θ-type charge-transfer salts. In doing so, one may study the effect of chirality and super(conductivity) within enantiomeric and diastereomeric salts.

The second type of material studied includes salts of metal trisoxalate anions with BEDT-TTF. A number of novel charge-transfer salts have been synthesised successfully, with some interesting and surprising serendipitous discoveries.. The synthetic method employed offers the potential for introducing a wide range of guest molecules, whereas previously these have been limited to solvent molecules. Such introductions may allow one to fine-tune the conducting properties via extension of the hexagonal cavity b axis, which in turn may increase the superconducting Tc in this family of salts, whilst adding further functionality to the material alongside depending on the guest identity. Despite extensive syntheses reported here, these represent only a small number of the vast pool of guest molecules available for one to utilise in discovering novel chiral-magnetic-conducting salts. The full potential of those reported have yet to be realised and one is honoured to have already been able to add to the wealth of literature surrounding these salts.4

Finally, two novel charge-transfer salts of BEDT-TTF with spiroborate have been characterised via electrical resistivity measurements. The discovery of this family of salts was established by the Martin research group very recently, such that the potential of these novel materials remains relatively untapped.5–7 The extensive potential for an array of further bidentate ligands forms the basis of further work in this area, and the novel salts reported provide new additions of both semiconducting and metallic-insulating members to said family.
A new family of chiral donors has been synthesised which can be employed not only with TCNQ (tetracyanoquinodimethane), but with a multitude of different sized/shaped anions to potentially lead to further chiral (super)conductors and/or switching materials. Much study upon the materials synthesised in this body of work is still available for future researchers, and one postulates that all three types of material studied may even be employed to formulate novel families with one another, such that the newly-realised chiral BEDT-TTF motifs may be employed with both the metal trisoxalate anions, as well as the spiroborate anions to realise even further novel multifunctional molecular conducting materials. Moreover, inclusion of chiral guest molecules may be employed in these new families using the methods described here, which have shown that using chiral guests can lead to chiral induction, thereby yielding single enantiomers of the anions employed.

Item Type:	Thesis
Creators:	Rusbridge, E.K.
Contributors:	Name Role NTU ID ORCID Martin, L. Thesis supervisor UNSPECIFIED UNSPECIFIED Fitzpatrick, A. Thesis supervisor UNSPECIFIED UNSPECIFIED Wallis, J. Thesis supervisor UNSPECIFIED UNSPECIFIED
Date:	February 2024
Rights:	The copyright in this work is held by the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed to the author.
Divisions:	Schools > School of Science and Technology
Record created by:	Laura Ward
Date Added:	06 Jan 2025 15:57
Last Modified:	06 Jan 2025 15:58
URI:	https://irep.ntu.ac.uk/id/eprint/52783