A Hydrogen‐Bond Flip‐Flop through a Bjerrum‐Type Defect

Abstract

Back and forth: Femtosecond two-dimensional infrared exchange spectroscopy was used to study the dynamics of the reversal of an intramolecular hydrogen bond. The H-bond reversal resembles a flip-flop motion that is facilitated by two concerted disrotatory torsional isomerizations and that occurs on a time scale of about 2 ps.