Crystal structure of a NIR-Emitting DNA-Stabilized Ag Nanocluster.

DNA has been used as a scaffold to stabilize small, atomically monodisperse silver nanoclusters, which have attracted attention due to their intriguing photophysical properties. Herein, we describe the X-ray crystal structure of a DNA-encapsulated, near-infrared emitting Ag nanocluster (DNA-Ag NC). The asymmetric unit of the crystal contains two DNA-Ag NCs and the crystal packing between the DNA-Ag NCs is promoted by several interactions, such as two silver-mediated base pairs between 3'-terminal adenines, two phosphate-Ca -phosphate interactions, and π-stacking between two neighboring thymines. Each Ag NC is confined by two DNA decamers that take on a horse-shoe-like conformation and is almost fully shielded from the solvent environment. This structural insight will aid in the determination of the structure/photophysical property relationship for this class of emitters and opens up new research opportunities in fluorescence imaging and sensing using noble-metal clusters.