Self-assembly of chromonic liquid crystals: a combined experimental and theoretical approach.

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The molecules that form chromonic liquid crystals are typically aromatics with hydrophilic groups on the periphery. These groups make the compounds soluble in water. Many dye and drug molecules are of this type. They are disc-like or plank-like in shape and have a strong tendency, even in dilute solution, to form long stacks, though layered phases have also been reported. These stacks may be positionally disordered (N phase) or they may be arranged in hexagonal patterns (M phase). Often the stacks are simple columns, though water-filled hollow chimney structures have also been proposed.The relationship between the molecular structure and the phase behaviour is very obscure. Seemingly small structural differences can have large effects on the phase diagram. This has practical implications, for unwanted aggregation of dye and drug molecules can render promising new formulations useless.In this proposal we seek to obtain a quantitative understanding of the structure-property relations of these chemicals. We will synthesise a series of naphthylamine sulphonic acid derivatives in which the chemical groups and the geometry are varied in a systematic way. We will experimentally examine the phase behaviour (varying also the salt concentration and the pH) and we will carry out computer simulation studies on state-of-the-art atomistic simulation models. We will also seek to develop simple theories to provide an underpinning framework to interpret these data. By combining synthesis, phase characterisation, simulation and theory in this systematic study, we aim to uncover the basic rules that govern the aggregation and phase properties of this important and fascinating class of molecules.