RAPID FADING PHOTO-RESPONSIVE MATERIALS

摘要

2H-naphtho[1,2 b]pyrans accordind to formula (I) and 3H-naphtho[2,1-b]pyrans according to formula (II) are photochromic and have increased rates of fade without change in wavelength by use of R<2> substituents chosen from structures (VII), (VIII) and (IX).