Synthesis of dimeric pyridylguanidinium based supramolecular structures stable in polar and aqueous solvent systems

Abstract

This thesis describes the synthesis of a series of pyridyl guanidinium-carboxylates. Dilution and spectroscopic studies are made thus affording information concerning the molecular forces controlling their dimerisation. Chapter I provides an introduction to the thesis and discusses, in the main part, the thermodynamics of self-assembly with particular focus given to guanidinium-carboxylates. Chapter II describes the syntheses and dimerisation studies undertaken and Chapter III contains the experimental procedures and results. The dimerisation of the pyridylguanidinium-carboxylates was investigated in DMSO and H₂O/DMSO mixtures using isothermal calorimetric and NMR dilution techniques and the relative importance of H-bonding, π- π stacking, electrostatic and hydrophobic interactions in constructing a dimeric self-assembled system in polar and aqueous environment has been investigated. While most of the guanidinium-carboxylates show excellent dimerisation in DMSO (~ K_dim = 7692±1124 M^-1) and 10% H₂O/DMSO (~ K_dim= 2695±151 M^-1), some of them exhibit entropy driven dimerisation in an aqueous environment containing up to 50% (~K_dim= 55±8 M^-1) and 75% (~K_dim= 27±7 M^-1) H₂O in DMSO.

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ORCID for Sally Bloodworth: orcid.org/0000-0003-2219-3635

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