Fluorescence of PRODAN in water: A computational QM/MM MD study

Fluorescent properties of PRODAN (6-propionyl-2-dimethylaminonaphthalene) in water were studied by means of excited state molecular dynamics simulations employing a quantum mechanical and molecular mechanical approach with the time-dependent density functional theory (TD-DFT QM/MM MD). The influence of solvation on PRODAN emission was investigated within several computational schemes. The best correspondence with the experimental emission spectrum was achieved for the planar excited state PRODAN conformer in the environment of 300 explicit water molecules with polarization effects included. Hence, it is demonstrated that an extended solvent environment and polarization effects are responsible for the strong solvatochromic shift of PRODAN emission in water.