Title
Plasmonic circular dichroism of vesicle-like nanostructures by template-less self-assembly of achiral Janus nanoparticles
Author
Jia E. Lu, Chou-Hsun Yang, Haobin Wang, Chi-Yung Yam, Zhi-Gang Yu, Shaowei Chen
Year
2018
Journal
Nanoscale
Abstract
Chiral nanostructures have been attracting extensive interest in recent years primarily because of the unique materials properties that can be exploited for diverse applications. In this study, gold Janus nanoparticles, with hexanethiolates and 3-mercapto-1,2-propanediol segregated on the two hemispheres of the metal cores (dia. 2.7 0.4 nm), self-assembled into vesicle-like, hollow nanostructures in both water or organic media, and exhibited apparent plasmonic circular dichroism (PCD) absorption in the visible range. This was in contrast to individual Janus nanoparticles, bulk-exchange nanoparticles where the two ligands were homogeneously mixed on the nanoparticle surface, or nanoparticles capped with only one kind of the ligands. The PCD signals were found to become intensified with increasing coverage of the 3-mercapto-1,2-propanediol ligands on the nanoparticle surface. This was accounted for by the dipolar property of the structurally asymmetrical Janus nanoparticles, and theoretical simulations based on first principles calculations showed that when the nanoparticle dipoles self-assembled onto the surface of a hollow sphere, a vertex was formed which gave rise to the unique chiral characteristics. The resulting chiral nanoparticle vesicles could be exploited for the separation of optical enantiomers, as manifested in the selective identification and separation of D-alanine from the L-isomer
Instrument
J-1500
Keywords
Circular dichroism, Chemical stability, Nanostructures, Materials