Thermal and photochemical properties of 4′-hydroxyflavylium in water–ionic liquid biphasic systems

The multistate/multifunctional properties of 4′-hydroxyflavylium in a water/1-n-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6]) biphasic system are described. The kinetics and thermodynamics of this flavylium salt have been fully characterised in aqueous solutions and compared to those obtained in [bmim][PF6]. The trans-chalcone is thermally more stable in the ionic liquid but shows efficient photoisomerisation to the cis-chalcone, allowing to define write–read–erase cycles in this biphasic system.