Excited-state double-proton transfer in the (3-methyl-7-azaindole)–(7-azaindole) hetero-dimer in the gas phase

The S1 ← S0 fluorescence excitation spectra have been measured for the dual hydrogen-bonded (3-methyl-7-azaindole)–(7-azaindole) hetero-dimer and its isotopomers in a supersonic free jet-expansion. The excited-state double-proton transfer (ESDPT) reaction occurs in the locally excited S1 state of the undeuterated (3-methyl-7-azaindole)*–(7-azaindole) dimer. It has been found that the removal of the exciton resonance interaction provides little effect on the ESDPT reaction.