US Patent 7556751 Photochromic materials having electron-withdrawing substituents

Photochromic materials comprising indeno-fused naphthopyrans having a first electron-withdrawing substituent and, in certain non-limiting embodiments, a second electron-withdrawing substituent are disclosed. The photochromic materials according to the various embodiments may display faster fade rates, bathochromic shift, and higher performance ratings compared to comparable indeno-fused naphthopyrans without the electron-withdrawing substituents. Photochromic compositions and articles, such as optical elements, incorporating the photochromic materials are also disclosed.