We investigated two DNA-stabilized silver nanoclusters (DNA-AgNCs) that show multiple absorption features in the visible region, and emit around 811 nm (DNA811-AgNC) and 841 nm (DNA841-AgNC). Both DNA-AgNCs have large...

DNA oligomers are known to serve as stabilizing ligands for silver nanoclusters (Ag N -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 N -DNAs differ significantly from previously reported Ag N -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 N -DNAs and significantly expands the space of structure–property relations that can be achieved for Ag N -DNAs.

The effect of replacing guanosines with inosines in the two stabilizing strands (5’-CACCTAGCGA-3’) of the NIR emissive DNA-Ag16NC was investigated. The spectroscopic behavior of the inosine mutants is position-dependent: when...

DNA‐stabilized silver nanoclusters (DNA‐AgNCs) are easily tunable emitters with intriguing photophysical properties. Here, a DNA‐AgNC with dual emission in the red and near‐infrared (NIR) regions is presented. Mass spectrometry data showed that two DNA strands stabilize 18 silver atoms with a nanocluster charge of 12+. Besides determining the composition and charge of DNA2[Ag18]12+, steady‐state and time‐resolved methods were applied to characterize the picosecond red fluorescence and the relatively intense microsecond‐lived NIR luminescence. During this process, the luminescence‐to‐fluorescence ratio was found to be excitation‐intensity‐dependent. This peculiar feature is very rare for molecular emitters and allows the use of DNA2[Ag18]12+ as a nanoscale excitation intensity probe. For this purpose, calibration curves were constructed using three different approaches based either on steady‐state or time‐resolved emission measurements. The results showed that processes like thermally activated delayed fluorescence (TADF) or photon upconversion through triplet‐triplet annihilation (TTA) could be excluded for DNA2[Ag18]12+. We, therefore, speculate that the ratiometric excitation intensity response could be the result of optically activated delayed fluorescence.