Hysteretic Control of Near‐infrared Transparency Using a Liquescent Radical Cation

Abstract

Al iquescent dihydrophenazine radical cation, 1C + •NTf 2 À ,s howed drastic changes in near-infrared (near-IR) transparency and opaqueness through hysteretic phase transitions with no measurable degradation of the compound even under aerated conditions.During the heating and slowcooling process (0.5 Kmin À1), its electronic and magnetic properties were altered clearly and repeatedly changed between solid and liquid states.T he liquid state was transparent to near-IR light (940 nm), but the solid state was opaque,despite both samples exhibiting asimilar green color under room light. Additionally, the liquid state was changed to aglass state under afast cooling process (2-10 Kmin À1). UV/Vis/near-IR and electron spinresonance spectroscopyr evealed that these drastic changes were attributable to the dynamic dissociation and association of a p-dimer structure for 1C + accompanying with the solidliquid phase transitions even under the neat conditions. À). These data can be obtained free of charge from TheC ambridge Crystallographic Data Centre.