Photochromic spirofluorenopyran compounds

US6331625A · kind A · utility

Assignee

• Optische Werke G. Rodenstock · DE

Inventors

• Claudia Mann · Munich, DE
• Udo Weigand · Munich, DE
• Manfred Melzig · Weßling, DE

Key dates

• Filing date: Apr 25, 2000
• Grant date: Dec 18, 2001
• Expiry date: Apr 25, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B5/23
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Photochromic spirofluorenopyran compounds corresponding to the general formula (I): ##STR1## in which B, B', R.sub.1 to R.sub.4 and G have the meanings defined herein. The compounds of the invention are useful in the production of photochromic articles, particularly articles made of synthetic resin materials, and exhibit rapid darkening and brightening rates, as well as long useful service lives. By appropriate selection of substituents, it is possible to adjust the properties of the compounds such as absorption maxima (color), brightening rate, etc.