Two of a Kind: Composition and Photophysics of Two Silver Nanoclusters Stabilized by the Same DNA Sequence

Sequence-structure relationships in DNA-stabilized silver nanoclusters (DNA-AgNCs) remain a central challenge in predicting their optical properties. Here, we show that a single guanine-rich DNA scaffold can direct the formation of two distinct silver nanoclusters within the same reaction mixture. While the clusters' composition and charge are very similar, their photophysical properties are surprisingly different. We present, for the first time, detailed structural insights into one of the two DNA-AgNCs: the near-infrared emitting silver nanocluster with a predominantly microsecond-lived excited state, DNA₂[Ag₁₇₊₂]¹³⁺. Remarkably, two guanines bridge the central 17-silver-atom cluster with two additional isolated silver atoms, which are further stabilized through interactions with cytosine and adenine nucleobases. These findings provide new insight into how DNA sequences drive AgNC formation and tune spectroscopic properties, advancing the rational design of near-infrared-emissive nanoclusters with tailored optical responses.