Density functional theory and quantum dynamics simulations have been used to study the double-proton transfer reaction in 2,2́-bipyridyl-3,3́- diol in the first singlet excited electronic state. This process is experimentally known to be branched: It consists of a fast, concerted reaction mechanism (τ ≈ 100 fs) and a stepwise reaction mechanism [with a fast initial step (τ ≈ 100 fs) and a slower final step (τ ≈ 10ps)]. Quantum dynamics simulations on a two-dimensional model reveal that the concerted reaction occurs despite the nonexistence of a concerted reaction path, but they fail to explain the relative slowness of the stepwise mechanism. A qualitative simulation using a three-dimensional model suggests that internal vibrational relaxation (IVR) might be the reason why the second stage of the stepwise mechanism is so slow.
|Publication status||Published - 20 Sep 2004|
- Excited states
- Proton transfer
- Quantum dynamics
- Reaction mechanisms