Photoionization and dynamic solvation of the excited states of 7-azaindole

The excited-state photophysics of the biological probe, 7-azaindole, are examined in water and methanol. Electrons in a presolvated state absorbing in the infrared appear within the excitation pulse width of 130 fs. 330 ± 100 fs is required for the presolvated electron to achieve the spectrum characteristic of the completely solvated electron. An excited-state transient absorbance decays in ∼350 fs for 7-azaindole and its methylated analog, N₁-methyl-7-azaindole (1M7AI), in the region 400-450 nm in water and methanol. The instantaneous appearance of the electron in the infrared is attributed to the decay of the ¹L_b excited-state that overlaps the ¹L_a excited state of 7-azaindole. The rapid decay of the excited-state transient absorbance is attributed to preferential, dynamic solvation of the ¹L₃ state. 7-Azaindole thus provides an interesting example of a molecule whose excited state is continuously and dynamically solvated but which also produces a species, e_aq^-, whose solvation appears to occur in a stepwise process.