Benzo[b]furan Platforms for Tailorable Photochromic Molecules

We report a series of photochromic molecules based on a benzo[b]furan core platform. A modular synthesis strategy allows for facile tuning of the thiophene appendages on the local furan moiety that participate in the key 6-π electrocyclization reaction at the origin of the reversible photochromism. This tuning enabled a broad palette of HOMO–LUMO energy gaps and visible chromic responses. In accord with our prior studies, frontier molecular orbital localization on the thienyl switching units served as a proxy for predicting successful photochromic reactions.