•Plot potential energy curve of 7-Azaindole (7-AI) and formic acid.

method：TD-B3LYP/6-31+G(d,p)

Extracurricular reading：Theoretical study on the double proton transfer in a hetero-hydrogen-bonded dimer of 11-propyl-6H-indolo-[2,3-b]quinoline (6HIQ) and 7-azaindole (7AI)

                            Normal Form                                                                                            

Transition State

Tautomer Form