Azomethine compounds (I) are new. Azomethine compounds of formula (I) and their organic or inorganic acid or base salts, their tautomers, optical isomers or geometrical isomers and/or their solvates, are new. R : linear or branched 1-4C-alkyl (optionally substituted by one or more hydroxy or imidazolium radicals, An ->；), halo or 1-4C-alkoxy； An ->；anion or its mixture； R1 : H or linear or branched 1-4C-alkyl； X : OH or N(R2)(R3)； R2, R3 : H or linear or branched 1-6C-alkyl (optionally substituted with one or more OH or 1-4C-alkoxy)； and n : 0-4. (1) substituted 3-amino-5,6-bis-phenylamino-pyridin-2-ol compounds of formula (II) and their organic or inorganic acid or base salts, their tautomers, optical isomers or geometrical isomers and/or their solvates； (2) a composition comprising (I) in a medium, or (II) and optionally comprising one or more oxidizing agents in a medium； (3) a method for dyeing keratin fibers, preferably human keratin fibers such as the hair, comprising either applying a dye composition comprising (I) in a medium to the fibers to obtain desired coloration, rising the fibers, optionally washing with shampoo and rinsed again, and drying or leaving the fibers to dry, or simultaneously or sequentially applying a dye composition comprising (II) and an oxidizing composition comprising the oxidizing agents to the wet or dry fibers； (4) a method for lightening the keratin fibers, comprising applying a dye composition comprising (I) in a suitable medium, where the composition is free of oxidizing agents, a cosmetic composition comprising one or more oxidizing agents to the fibers, and the compositions are sequentially or simultaneously applied to the fibers, rising the fibers, optionally washing with shampoo and rinsed again, and drying or leaving to dry the fibers； and (5) a multicompartment device comprising a first compartment containing a composition comprising (I) or (II) and a second compartment comprising the oxidizing agents. [Image] [Image].
