Photochromism of a novel spiropyran derivative based on calix[4]arenes

A novel spiropyran derivative carrying a calix[4]arene group has been synthesized through incorporating two spirobenzopyran groups into one 1,3-substituent calix[4]arene derivative. Photochromic properties were studied under alternate irradiation of ultraviolet light and visible light in acetonitrile. Addition of metal ions (such as Mg2+, Ca2+, Eu3+) decreased the first-order thermal decoloration rate constants to different extent. The colored forms of the compound are more stable than the parent 1′,3′,3-trimethyl-6-nitro-8-methanolspirobenzopyran. It provides a method of increasing stability of the merocyanine forms which are of high importance for applications of photochromic materials, especially in the presence of Eu3+. The compound may be applied as photochromic materials for its high thermal stability of colored forms.