Аннотация:The review describes the photochromism of crown-ether systems based on pericyclic reactions. The photochromic transformations and the obsd. spectral changes or changes in phys. or chem. behavior are related to the modification of the system geometry and electron distribution. A novel approach to the modification of photochromic systems includes the exploration of the complex formation process in crown ether contg. photochromic systems. The results obtained show that the introduction of crown-ether moieties into dye mols. affords compds. that can change their spectral and photochromic properties upon complex formation. The approach offers the possibility of synthesizing new photochromic substances characterized by enhanced photostability, high sensitivity, and a broad range of operating wavelengths. Yet another important feature of the novel systems is reversible change in the capacity of a photochromic host mol. for assocn. with guests upon irradn. The researches believe that the novel photochromic systems can now be regarded as being promising for traditional applications (photochromic ophthalmic lenses or camera filters, reversible holog. systems, cosmetics) and for mol. electronics, biomimetic chem., and optical information storage. A review with 55 refs.