| abstract |
Described are novel reversible photochromic 3H-naphtho[2,1-b]pyran compounds, examples of which are substituted with an oxy-bearing substituent at the number 8 carbon atom and with either an alkyl group at the number 7 carbon atom or with a carbonyl bearing substituent at the number 9 carbon atom and certain substituents at the 3-position of the pyran ring, e.g., 3,3-spirofluoren-9-ylidene-8-methoxy-9-carbomethoxy-3H-naphtho[2,1-b]pyran. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline) type compounds, are also described. |