Isolation of a hydrogen-bonded complex based on the anthranol/anthroxyl pair: formation of a hydrogen-atom self-exchange system.

A hydrogen-bonded complex was successfully isolated as crystals from the anthranol/anthroxyl pair in the self-exchange proton-coupled electron transfer (PCET) reaction. The anthroxyl radical was stabilized by the introduction of a 9-anthryl group at the carbon atom at the 10-position. The hydrogen-bonded complex with anthranol self-assembled by π-π stacking to form a one-dimensional chain in the crystal. The conformation around the hydrogen bond was similar to that of the theoretically predicted PCET activated complex of the phenol/phenoxyl pair. X-ray crystal analyses revealed the self-exchange of a hydrogen atom via the hydrogen bond, indicating the activation of the self-exchange PCET reaction between anthranol and anthroxyl. Magnetic measurements revealed that magnetic ordering inside the one-dimensional chain caused the inactivation of the self-exchange reaction.