Helically grooved gold nanoarrows: Controlled fabrication, superhelix, and transcribed chiroptical switching

Abstract

Plasmonic chiroptical materials, coupled by chirality and surface plasmons, have been attracting great interest due to their potential applications, such as photonics, chiral recognition, asymmetric catalysis and biosensing. Herein, we constructed a new chiral plasmonic nanostructure-helically grooved gold nanoarrows (HeliGNAs) by introducing L-/D-cysteine (L-/D-Cys) during the growth of the gold nanoarrows (GNAs). The variation of the concentration of L-/D-Cys leads to the HeliGNAs with a tunable plasmonic circular dichroism (PCD). Moreover, HeliGNAs can self-assemble into a superhelix at a higher concentration of L-/D-Cys, whose chirality can be transcribed to an achiral azobenzene derivative localized in the hotspots from the superhelix of HeliGNAs. A chiroptical switch is established based on the photoisomerization of azobenzene. This work provides not only a new way for fabricating helically featured gold nanostructure but also discloses interaction between chiral molecules/achiral plasmon, chiral plasmon/achiral molecules, thus deepening the understanding of plasmon-chirality-coupled circular dichroism.