Photochromic spiro compounds, process for their preparation, and their use

摘要

Novel photochromic spiro compounds of the formula (I) <IMAGE> which are obtained by cycloaddition of cyclopropenes or precursors thereof onto bifunctional coreactants, such as the diazines pyrimidine or pyrazine, or bridged dimers, such as bispyridyl, with double cycloaddition. The novel compounds enable a specific broadening of the absorption range of the resultant photochromic compounds for a multiplicity of applications, for example as dosimeters, sensitisers and in general for measurement, storage and recording purposes.