Abstract: Described are novel reversible photochromic naphthopyran compounds, examples of which are compounds having a cycloalkyl ester substituent at the number 5 carbon atom and optionally certain substituents at the number 6 carbon atom of the naphtho portion of the naphthopyran and certain substituents at the 2-position of the pyran ring. Substituents may also be present at the number 7, 8, 9 or 10 carbon atoms of the naphtho portion of the naphthopyran. These compounds may be represented by the following graphic formulae: Also described are various substrates, e.g., paper, glass, organic polymeric materials, etc., that contain or that are coated with such compounds. Optically clear articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, indenonaphthopyrans, benzopyrans, oxazine-type compounds, etc., are also described.

Abstract: Described are novel reversible photochromic naphthopyran compounds, examples of which are compounds having a cycloalkyl ester substituent at the number 5 carbon atom and optionally certain substituents at the number 6 carbon atom of the naphtho portion of the naphthopyran and certain substituents at the 2-position of the pyran ring. Substituents may also be present at the number 7, 8, 9 or 10 carbon atoms of the naphtho portion of the naphthopyran.