Acid–base properties of 3,5-dimethyl-1,7-diphenyl derivative of bis-pyrazolopyridine in non-aqueous solutions

Acid–base properties of 3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4′,3′-e]-pyridine (BPP) in the ground state and in the first excited singlet state were investigated in non-aqueous solutions. Absorption and stationary fluorescence spectroscopy, supersonic jet spectroscopy as well as the calculations of effective valence potentials were applied as methods. The sequence of the protonation of BPP nitrogen atoms in solutions and the formation of complexes with water in molecular beams were discussed.