Density functional study of the TiO₂-dopamine complex

The binding energies and excitation energies of dopamine interacting with TiO₂ clusters of different sizes representing an anatase surface are calculated. Results indicate that bidentate adsorption of dopamine on undercoordinated sites containing a TiO double bond is more stable than monodentate or molecular adsorption on the (1 0 1) anatase surface. A large red shift in the absorption spectrum of TiO₂-dopamine is calculated, in agreement with experimental studies. We also investigate how the optical properties of TiO₂-dopamine are affected by adding carboxyl thymine and subsequent base pairing with adenine.