where the coupling |H if SOC | 2 is given by the spin-orbit coupling matrix elements (SOCME) between the relevant states. The SOCME values were calculated using Quasi-Degenerate Perturbation Theory (QDPT), combined TDA to describe the singlet-triplet interactions derived from TDA/TD-DFT computations at the CAM-B3LYP/Def2-TZVP level. The total ISC rate (k ISC ) is given by the sum over all ISC rates from the S1 state to the m-th excited electronic triplet state energetically below. Due to computational cost, the explicit solvent systems comprised three water molecules surrounding the solute. The position of these three molecules was determined through Monte Carlo (MC) simulations, employing standard Metropolis sampling protocols within the canonical (NPT) ensemble. The simulations were performed at a temperature of 25°C in a cubic simulation box, where the volume was defined based on the experimental density of water and included 1000 solvent molecules. The complete simulation involves a thermalization stage of 100,000 MC steps and a production stage of 100,000 MC steps for averaging. All simulations were performed using the DICE program. The most relevant structures containing three hydrogen bonds were selected for further optimization with explicit solvation.