Abstract
Mirror symmetry breaking in materials is a fascinating phenomenon that has practical implications for various optoelectronic technologies. Chiral plasmonic materials are particularly appealing due to their strong and specific interactions with light. In this work we broaden the portfolio of available strategies toward the preparation of chiral plasmonic assemblies, by applying the principles of chirality synchronization—a phenomenon known for small molecules, which results in the formation of chiral domains from transiently chiral molecules. We report the controlled cocrystallization of 23 nm gold nanoparticles and liquid crystal molecules yielding domains made of highly ordered, helical nanofibers, preferentially twisted to the right or to the left within each domain. We confirmed that such micrometer sized domains exhibit strong, far-field circular dichroism (CD) signals, even though the bulk material is racemic. We further highlight the potential of the proposed approach to realize chiral plasmonic thin films by using a mechanical chirality discrimination method. Toward this end, we developed a rapid CD imaging technique based on the use of polarized light optical microscopy (POM), which enabled probing the CD signal with micrometer-scale resolution, despite of linear dichroism and birefringence in the sample. The developed methodology allows us to extend intrinsically local effects of chiral synchronization to the macroscopic scale, thereby broadening the available tools for chirality manipulation in chiral plasmonic systems.
Highlights
Mirror symmetry breaking in materials is a fascinating phenomenon that has practical implications for various optoelectronic technologies
One route to achieve this goal comprises the incorporation of metal nanoparticles within chiral liquid crystal (LC) matrices.[47−50] While yielding materials that exhibit interesting optical properties, this method is limited by the requisite that the organic template must be intrinsically chiral
One of the most prominent cases of chiral synchronization is related to selected bent-core liquid crystalline compounds[52,53] that are able to form helical nanofilament (HNF) phases.[54,55]
Summary
Mirror symmetry breaking in materials is a fascinating phenomenon that has practical implications for various optoelectronic technologies. Scientists and engineers aim at controllably fabricating nanoarchitectures with sophisticated, hierarchical structures, in which the spatial arrangement of building blocks defines the optical response of the material.[1−6] Development of chiral assemblies made of plasmonic nanoparticles is interesting due to their superior light−matter interactions in comparison to purely organic matter.[3,7−12] Stimulated by recent visionary reports, much interest has been revived toward applying the principles of chiral plasmonics to realize superlenses,[13] chiral catalysts,[14,15] negative refractive index materials,[16] perfect absorbers,[17] broadband circular polarizers,[18] selective reflectors,[19] biosensors,[20] chiral quantum optical devices,[21] chiral emission,[22] and biomanipulation.[23] For this purpose, harnessing chiral plasmonic properties in complex, organic−inorganic nanocomposites is often required Such composites are usually achieved by either combining intrinsically chiral NPs24−27 with achiral materials, through chirality transfer from chiral entities to achiral NPs,[28] or by using other symmetry breaking stimulants, like circularly polarized light[29] or imprinting.[30] The self-assembly driven,[31−34] template-based approach is appealing, as it provides the ability to tailor chiral plasmonic systems. We used a LC mediated method, which results in helical nanofilaments selectively decorated with gold NPs.[66]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
