| abstract |
There are essentially no polymerizable unsaturated groups, a) indeno [2 ', 3': 3,4] naphtho [1,2-b] pyran; And b) electron-attracting non-conjugated groups bonded at the 11-position of indeno [2 ', 3': 3,4] naphtho [1,2-b] pyran. Other embodiments include various substituents at different positions of indeno [2 ', 3': 3,4] naphtho [1,2-b] pyran. Also provided is a photochromic article comprising a substrate and one of the photochromic materials in contact with at least a portion of the substrate. |