Gold Nanoparticles Thin Films with Thermo‐ and Photoresponsive Plasmonic Properties Realized with Liquid‐Crystalline Ligands

Robust synthesis of large‐scale self‐assembled nanostructures with long‐range organization and a prominent response to external stimuli is critical to their application in functional plasmonics. Here, the first example of a material made of liquid crystalline nanoparticles which exhibits UV‐light responsive surface plasmon resonance in a condensed state is presented. To obtain the material, metal cores are grafted with two types of organic ligands. A promesogenic derivative softens the system and induces rich liquid crystal phase polymorphism. Second, an azobenzene derivative endows nanoparticles with photoresponsive properties. It is shown that nanoparticles covered with a mixture of these ligands assemble into long‐range ordered structures which exhibit a novel dual‐responsivity. The structure and plasmonic properties of the assemblies can be controlled by a change in temperature as well as by UV‐light irradiation. These results present an efficient way to obtain bulk quantities of self‐assembled nanostructured materials with stability that is unattainable by alternative methods such as matrix‐assisted or DNA‐mediated organization.