Flavylium based dual photochromism: addressing cis–trans isomerization and ring opening-closure by different light inputs†
Abstract
The multistate system of 4′,7-dihydroxy-3-methoxyflavylium is constituted by a multiequilibrium involving trans-chalcone, cis-chalcone, hemiketal, flavylium cation and quinoidal base. This system possesses two independently addressable inter-connected photochromic systems based on the cis–trans isomerization and ring opening-closure of the hemiketal.