Switching of Adsorption Properties in a Zwitterionic Metal–Organic Framework Triggered by Photogenerated Radical Triplets

A new metal–organic framework
(MOF) that features photoreactive
zwitterionic pyridinium 4-carboxylate units has been designed. Upon
UV light irradiation, these units form radical triplets permitted
by intramolecular electron transfer between anionic carboxylate and
cationic pyridinium groups. This reversible light-responsive behavior
creates on/off switchable charge gradients localized at the MOF’s
major adsorption sites and, thus, allows significant control of the
gas sorption process. It is shown that this strategy offers new design
routes for accessing stimulus-responsive materials.