Synthesis of redox-responsive tetrathiafulvalene derivatives with amphiphilic properties to be used in soft materials
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Date
2024
Authors
Tshehla, Paulos Katlego
Journal Title
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Publisher
University of the Free State
Abstract
The well-known electron-rich donor system, Tetrathiafulvalene (TTF) has gained excessive interest in the field of supramolecular chemistry and complex ligand research. Continuous advancements in synthesis has allowed TTF along with its derivatives to be integrated into various intricate molecular systems. Such that, these systems have been investigated for their potential applications as sensors, models for electron transfer, molecular machines and many other applications. The study displayed in this piece of writing will examine the incorporation of TTF moieties through preparation by synthesis, as well as their characterisation. With the motive to add to the recent and existing synthetic advances, for utilization in constructing versatile systems of broad applications.
A series of functionalised bis- and tetra-tetrathiafulvalene derivatives has been prepared. A result stemming from a series of synthesis producing TTF intermediates, later used as key precursors for the successful synthesis of TTF derivatives. Amongst those, is the TTF thiolate anion used as a key intermediate which has shown to be quite a versatile reagent for this purpose. Shelf-stable precursors of the TTF thiolate anion have been prepared, making the preparation of novel, highly functionalised, amphiphilic cationic / anionic TTF derivatives 4 and 5 feasible. The series of steps include various reactions: cyclization, cross coupling and self-coupling, de-protection, re-alkylation, and nucleophilic substitution reactions. This synthetic pathway allows the tailoring of the properties of the TTF entity by the variation of the substitution pattern. For feasibility of the amphiphilic character, the analogues prepared constitute of long alkyl chains at different positions. This character adds in rendering these entities as versatile electron donor systems, well suited for use in construction of novel redox assemblies.
Through careful adjustments and development of methodologies, a range of symmetrical and unsymmetrical TTF derivatives of different substituents was covered. From alkyl-halides bearing TTF derivatives to the 1-methyl-imidazole units fused to the TTF frameworks. Certain compounds were obtained in significantly high yields. Such as the 1-methyl-imidazole bearing TTF derivative, 4,5-bis(1-methylimidazole-3-propylthio)-6,7-bis(propylthio)tetrathiafulvalene 4a at a yield of 94%. With its identity qualitatively confirmed by high-resolution mass spectroscopy and NMR analysis.
In the study, several purification techniques were implemented with the hopes of producing highly pure and well isolated compounds. Some of the reactions produced several products which were difficult to separate. An attempt to conduct electrochemical studies on the new multi-TTF derivatives, was deemed unsuccessful for various reasons covered in the discussion.
Description
Dissertation (M.Sc.(Chemistry))--University of the Free State, 2024