Phototropic 2,4,5-triphenylimidazolyl radicals and dimers thereof

Abstract

Abstract 2,4,5-triphenylimidazolyl radicals and their dimers (2,2''4,4''5,5''- hexaphenyl biimidazoles) having on the phenyl groups from 1 to 10 substituents free from a hydrogen atom capable of reacting with methyl magnesium iodine, one such substituent being in the other position on the 2-phenyl group and having a sigma value below o.7. The 2-phenyl group can contain up to four substituents, while the 4 and 5 phenyl groups can contain up to three substituents each. The radicals and the dimers are stable and form a photochromic system finding utility as components in sun shields or shades. They are prepared by oxidizing the corresponding substituents 2,4,5 triphenylimidazole to form the biimidazole which is dark stable. The radical forms upon exposure of the biimidazole to a light source and is stable in the presence of the light radiation.

Inventors

• 👤 L Cescon

Bibliographic Details