Vastly Increased Mesophase Range due to Superstructure Formation from In Situ Prepared Gold Nanoparticles with Liquid Crystalline Ligands: Toward Enhanced Optoelectronic Applications

Gold nanoparticle (Au NP)-liquid crystal (LC) composites have gained considerable interest in developing cutting-edge electro-optical materials. This study introduces an innovative synthetic approach that significantly augments the capabilities of Au NP-LC composites by utilizing an amine-functionalized LC as both a reducing and capping agent in the refined Brust–Schiffrin method. In its standard form, this method yields Au NP-LC composites with appealing features like improved clearing temperature. However, the optical characteristics do not display any additional features and resemble simple LC–ligand functionalized Au NP, attributed here to the surplus LC employed to obtain the dual capabilities of reduction and capping. Thus, it was gratifying to observe a dramatic enhancement in mesophase stability with the removal of just a few percentages of excess LC, which is attributed to a remarkable and unprecedented one-dimensional superstructure formation. Furthermore, the removal of surplus LC caused the composite to exhibit Fano-like resonance in the UV–vis spectrum, a noteworthy optical feature likely resulting from dynamic plasmonic interactions, including plasmon–polariton interactions and lattice plasmon modes. Thus, the simple yet robust protocol employed yields Au NP-LC composites with an ultrawide thermal range of the mesophase that paves the way for realizing next-generation electro-optic materials featuring enhanced performance and response.