DNA Stabilizes Eight-Electron Superatom Silver Nanoclusters with Broadband Downconversion and Microsecond-Lived Luminescence

Abstract

DNA oligomers are known to serve as stabilizing ligands for silver nanoclusters (Ag_<i>N</i>-DNAs) with rod-like nanocluster geometries and nanosecond-lived fluorescence. Here, we report two Ag_N-DNAs that possess distinctly different structural properties and are the first to exhibit only microsecond-lived luminescence. These emitters are characterized by significant broadband downconversion from the ultraviolet/visible to the near-infrared region. Circular dichroism spectroscopy shows that the structures of these two Ag_<i>N</i>-DNAs differ significantly from previously reported Ag_<i>N</i>-DNAs. We find that these nanoclusters contain eight valence electrons, making them the first reported DNA-stabilized luminescent quasi-spherical superatoms. This work demonstrates the important role that nanocluster composition and geometry play in dictating luminescence properties of Ag_<i>N</i>-DNAs and significantly expands the space of structure-property relations that can be achieved for Ag_<i>N</i>-DNAs.