Photo- and ionochromic properties of new spirobenzochromene-pyranoquinoline

A compound of the new spirobipyran-quinoline series possesses weakly pronounced photochromic properties at room temperature. Its interaction with Co²⁺, Ni²⁺, Zn²⁺ and Cd²⁺ ions leads to intensely colored complexes absorbing in the λ> 600 nm region, which is important for the study of biological objects. Up to three merocyanine molecules are capable of binding one metal ion, which is not typical for the previously studied indoline analogs.