Micro Solvation Effect of Methanol on Excited-State Dynamics of Protonated Tryptophan and Dopamine.

The electronic and vibrational cryogenic ion spectroscopy of protonated tryptophan (TrpH) and dopamine (DAH) complexed with methanol has been recorded. These two biological chromophores exhibit ultrafast photochemistry due to excited-state proton transfer (ESPT). We have established the relationship between the structure of the complexes and their photodynamics and compared them with recent results obtained in hydrated complexes.

Conformer-selective Photodynamics of TrpH -H O.

The photodynamics of protonated tryptophan and its mono hydrated complex TrpH -H O has been revisited. A combination of steady-state IR and UV cryogenic ion spectroscopies with picosecond pump-probe photodissociation experiments sheds new lights on the deactivation processes of TrpH and conformer-selected TrpH -H O complex, supported by quantum chemistry calculations at the DFT and coupled-cluster levels for the ground and excited states, respectively. TrpH excited at the band origin exhibits a transient of less than 100 ps, assigned to the lifetime of the excited state proton transfer (ESPT) structure.