A visible-light-driven molecular motor based on barbituric acid
Kim Kuntze, Daisy R. S. Pooler, Mariangela Di Donato, Michiel Hilbers, Pieter van der Meulen, Wybren Jan Buma, Arri Priimägi, Ben L. Feringa, Stefano Crespi
Abstract
H NMR experiments we found that these motors operate similarly to push-pull second-generation overcrowded alkene-based molecular motors. Interestingly, the hydroxy group at the stereocentre enables a hydrogen bond with the carbonyl groups of the barbituric acid lower half, which drives a sub-picosecond excited-state isomerisation, as observed spectroscopically. Computational simulations predict an excited state "lasso" mechanism where the intramolecular hydrogen bond pulls the molecule towards the formation of the metastable state, with a high predicted quantum yield of isomerisation (68%) in gas phase.