Fine-tune chiroptical activity in discrete chiral Au nanorods

Accurate researches on the surface plasmon resonance (SPR)-based applications of chiral plasmonic metal nanoparticles (NPs) still remain a great challenge. Herein, a series of chiral plasmonic metal NPs, e.g., chiral Au nanorods (c-Au NRs), c-Au@Ag core–shell, and c-Au@TiO₂ core–shell NRs, with different chiroptical activities have been produced. Plasmonic circular dichroism (PCD) bands of c-Au NRs can be precisely tailored by tuning the longitudinal SPR (LSPR) and amount of Au NRs as seeds. Besides, a shift of PCD bands within ultraviolet–visible–near infrared ray (UV–vis–NIR) region can also be achieved through the functionalization of a shell of another metal or semiconductor. Interestingly, chirality transfer from c-Au core to Ag shell leads to new PCD bands at the near-UV region. The tuning of PCD bands and chirality transfer are confirmed by our developed theoretical model. Developing chiral Au NRs-based chiral plasmonic nanomaterials with tunable chiroptical activities will be helpful to understand the structure-direct PCD and to extend circularly polarized-based applications.