Effect of Microhydration in Tuning the Photophysical Behavior of a Luminescent DNA Probe Revealed by Non‐Adiabatic Dynamics

We report non‐adiabatic dynamics, performed in the surface hopping formalism, of 2‐thienyl‐3‐hydroxychromone, an environment‐dependent luminescent organic DNA probe. In particular we have shown that the first shell solvent water molecules undergo a rather complex reorganization upon light excitation. This involves also the triggering of a water‐mediated proton transfer process which leads to the formation of the tautomeric structure. The presence of this solvent‐mediated transfer mechanism globally diminishes the intersystem crossing efficiency, and hence the population of the triplet state manifold, as compared to the non‐solvated systems. Our results also point out the non‐innocent role of solvent networks in tuning complex photophysical processes, while opening competitive relaxation channels.