Chirality in gold-LC nanocomposites and heliconical systems

The research presented in this thesis is focused towards the design and synthesis of chiral liquid crystal gold nanoparticle nanocomposites and all of the related molecular sub-structures. It is intended that such organic-inorganic hybrid materials will combine the good processing properties of liquid crystals, such as forming soft anisometric condensed matter, low cost and photolithographic patterning, together with the unique optically plasmonic behaviour of nanoscale metal nanoparticles to interact with circularly polarized light.The synthetic methods of mesogenic ligands: calamitic mesogen with thiol end and discogen with disulfide function, were carried out and optimized to increase the yield, convenience and compatibility of soft ligands on solid gold. A synchrotron radiation circular dichroism technique was used here to detect the structural twist of collective NP assembly. The chiral transfer of functionalized AuNPs was investigated in calamitic hosts to realize the detection, visualization, measurement and quantification of chirality based on systematic optical observation. Macroscopic liquid crystal behaviour was observed for the undiluted gold nanoparticles organic-modified by the designed chiral discogen. Extended explorations on nematic twist-bend phase via circular dichroism mapping methods demonstrated the presence of doubly degenerate domains with opposite handedness. Besides, the chiral effects on bent-shaped dimer experimentally induced a new phase between cholesteric phase and NTB phase, which was confirmed by OPM and DSC tests