| abstract |
The invention relates to specific photochromic h-annellated benzo[f]chrome-derivatives, in addition to the use thereof in all types of plastic, in particular for ophthalmic purposes. The invention relates specifically to photochromic compounds derived from benzo[f]chromenes, said compounds comprising in their closed form particular long wave length absorptions maxima and good performance in the open, coloured form, whereby good harmony is achieved with the indenonaphthopyranes which are diffused in said phototropic glass in applications of phototropic glass. |