| abstract |
Methine dyes (I) which conform in one of their tautomeric forms to the general formula <IMAGE> where Y1 is in both or either case an electron-attracting group and the other Y1 is hydrogen, Y2 is in each case, independently of the others, hydrogen, -CN, halogen, C1-C6-alkyl, C5-C7-cycloalkyl, phenyl, pyridyl or together with a further Y2 a five- or six-membered ring which may have a fused-on benzene ring, R is hydrogen, C1-C20-alkyl, C7-C10-aralkyl or beta -hydroxyethyl and n is 1, 2, 3, 4, 5 or 6 and the groups <IMAGE> are identical or different five- or six-membered heterocyclic radicals, except 1,2,4-oxadiazol-5-yl, and the radicals D may be substituted and/or fused and can be present in the quaternized (cationic) or deprotonated (anionic) form, the compounds of the formulae <IMAGE> <IMAGE> being excepted, have a very high molar absorption within the range from 500 to 1200 nm and are in many cases readily soluble in organic solvents and/or thermoplastics or crosslinked plastics, which is why these dyes are highly suitable for optical recording media; a process for preparing (I); and optical recording media which contain (I). |