| abstract |
Described are novel reversible photochromic 2H-naphtho[1,2-b]pyranncompounds, examples of which are compoundsnhaving certain substituents at the number 5 carbon atom of thennaphtho portion of the naphthopyran and at the 2-position ofnthe pyran ring. Certain substituents may also be present atnthe number 6, 7, 8, 9 or 10 carbon atoms of the naphthonportion of the naphthopyran. Also described are organic hostnmaterials that contain or that are coated with such compounds.nArticles such as ophthalmic lenses or other plasticntransparencies that incorporate the novel naphthopyranncompounds or combinations thereof with complementarynphotochromic compounds, e.g., spiro(indoline) type compounds,nare also described. |