| abstract |
Described are novel reversible photochromic benzopyran compounds, examples of which are compounds substituted at the 2-position of the pyran ring with a dibenzo-fused 5 member heterocyclic compound; other enumerated substituents at the other 2-position of the pyran ring; and a substituted or unsubstituted benzo, benzothieno or benzofurano group fused to the benzo portion of the benzopyran. 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 benzopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline) type compounds, are also described. |