Femtosecond intramolecular proton transfer in photoexcited mono- and dienol derivatives of bipyridine

A femtosecond study of the intramolecular proton transfer dynamics in photoexcited mono- and dienol derivative compounds of pyridine is reported. It is shown that when a strongly electron-withdrawing substituent is attached to [2,2′-bipyridyl]-3,3′-diol, the excited-state proton transfer of this compound is changed from a double-proton transfer to a single-proton transfer. The excited-state single-proton transfer time in the title compounds is <150 fs.