Ionic Strength–Mediated Control of Liquid Crystals in Pyrene–Dipeptides: Structural Insight via SANS

Pyrene derivatives are valuable liquid crystalline (LC) materials due to their strong π–π stacking, rigid aromatic cores, and intrinsic fluorescence. By conjugating pyrene with amphiphilic dipeptides such as FF and FV, we designed systems (PyrFF and PyrFV) that combine the photophysical properties of pyrene with the self-assembling tendencies of short peptides, enhancing responsiveness and tuneability. Previous SANS experiments revealed LC ordering in 1D scattering and anisotropic alignment in 2D patterns for both PyrFF and PyrFV. We further observed that the addition of alkali metal salts significantly affects viscosity and birefringence, suggesting that ionic strength can modulate LC phase behaviour. In this proposal, we aim to investigate the tunability of LC phases by systematically varying salt type and concentration. Additionally, we will explore the impact of thermal annealing, which is known to induce structural transitions such as micelle disassembly and reorganization. Gaining precise control over these transitions is essential for the rational design of LC materials with responsive behaviour. SANS offers a unique capability to characterise nanoscale organisation and directional alignment in these systems, providing structural insights critical for tuning LC phase behaviour. Such control over supramolecular ordering enables the development of next-generation materials for optoelectronics, sensors, actuators, photonic devices, and soft robotics.