Chirally assembled plasmonic metamolecules from intrinsically chiral nanoparticles

Significant chiroptical responses could be generated by chiral coupling of achiral plasmonic nanoparticles, or originated from intrinsically chiral plasmonic nanoparticles. Here we create dimeric plasmonic metamolecules possessing both chiral coupling between nanoparticles and intrinsic chiroptical responses derived from nanoparticles themselves. These plasmonic metamolecules are prepared by assembling helical plasmonic nanorods (HPNRs) with intrinsic chirality in chiral manners on DNA origami template. Two HPNRs with the same or opposite chirality, or one HPNR and one achiral gold nanorod, are coupled chirally into dimeric metamolecules with intriguing plasmonic circular dichroism (PCD). We found that both of the intrinsic chirality of constituent HPNRs and the chiral coupling contribute to the overall PCD while their weights are different in different metamolecules and vary in different wavelength range for a certain metamolecule. Comparing to conventional chiral plasmonic metamolecules from achiral nanoparticles, or discrete chiral nanoparticles, these metamolecules bring more dimensions for tailoring chiroptical responses and make it more flexible to design plasmonic nanodevices with custom PCD.