| abstract |
Photochromic naphthacenequinones, their preparation and the use thereof Abstract of the Disclosure Compounds of formula I or V or mixtures thereof (I), wherein R is unsubstituted C6-C14aryl or C6-C14aryl which is substituted by C1-C12alkyl,C1-C12alkoxy, C1-C12alkylthio, phenyl, benzyl, -CN, -CF3, halogen or -COOR5, and R5 is H, C1-C18alkyl, cyclohexyl, cyclopentyl, phenyl, C1-C12alkylphenyl, benzyl or C1-C12alkylbenzyl, and at least one of the substituents R1 to R4 is -F, -Cl or -Br, or is independently the group RO-, and the other substituents R1 to R4 are H, -F, -Cl or -Br, are reversible photochromic systems which can be used for contrast formation, light absorption or for the reversible optical storage of information. |