Ground and Excited State Intramolecular Proton Transfer in OCCNN Ring
Chemical Physics Letters
Molecular orbital calculations reveal that the keto tautomer of HOCHCHNHNCH2, unlike the enol, does not represent a minimum in the ground state proton transfer potential. Excitations to the first excited singlet or triplet state leads to a rapid and barrierless transfer to the keto which becomes strongly preferred. Similar conclusion apply to a larger system with a full aromatic ring appended.
Duan, X. and Scheiner, Steve, "Ground and Excited State Intramolecular Proton Transfer in OCCNN Ring" (1993). Chemistry and Biochemistry Faculty Publications. Paper 565.