KCS

The interaction between a merocyanine (MC) dye and calix[4]pyrrole (CP) through hydrogen bonding is well known(eq.1). This MC-CP complex can then be destroyed by the anion, such as halogen anion, reforming a Cl^--CP complex and a colored MC species. This was verified that the formation of the complex MC1-CP and displacement of the complex with Cl^- anion with the production of the colored MC species back. It’s also very well known that thermo- and photochromic spiropyran is equilibriated with the open-form merocyanine MC2 (eq.2), after exposure to the light. However, equilibrium constants can be hardly obtained since the exact extinction coefficient of MC2 is not known. Thus a new method is applied to get an exact extinction coefficient value of the MC2 species and hence determined equilibrium constant Ke, utilizing the MC-CP complexation.