How Water Regulates Nonradiative Deactivation of DNA-Templated Green-Yellow Rod-Shaped Silver Clusters

The rational design of imaging probes based on DNA-stabilized silver clusters focuses on the key structural factors that affect fluorescence efficiency. We theoretically examined structural features determining nonradiative deactivation of five green or yellow-emitting fluorophores based on oligonucleotide-stabilized rod-shaped silver clusters. It was demonstrated that reducing the direct interaction between water and the silver cluster decreases the rate of internal conversion to the ground state, while increasing this interaction accelerates internal conversion. When water molecules cannot contact the silver cluster surface, variation in the number of guanines relative to the total number of bound nucleotides alters the energy gap between the lowest excited singlet and the closest triplet states, which modulates the rate of intersystem crossing quenching. These approaches could serve as the primary strategies for enhancing the fluorescence quantum yield of the green-yellow silver clusters we investigated.