Patent ID: 6441191
Filing Date: 2002-08-27
Classification: C09B,G03C,Y10S

Abstract:
A cyanine dyestuff comprising a compound of formula I in which R1 and R3 independently of one another are hydrogen, (C1-C6)-alkyl which is unsubstituted or monosubstituted by halogen or phenyl, or unsubstituted or mono- or di-substituted phenyl, and R3 furthermore is also halogen or (C3-C7)-cycloalkyl, but wherein no sulpho or sulphonate groups, no carboxyl or carboxylate groups and no sulphato groups may occur as a substituent in phenyl groups, wherein the sulphonate groups are in the 5-position of the terminal indole rings, and M+ is a monovalent cation or one equivalent of a polyvalent cation, but excluding that compound of formula I in which, simultaneously, R1 and R2 are methyl, R3 is hydrogen and M+ is Â½ Ni2+, that compound in which, simultaneously, R1 and R2 are ethyl, R3 is methyl and M+ is K+, and that compound in which, simultaneously, R1 and R2 are methyl, R3 is hydrogen and MâŠ• is KâŠ•, said compound exhibiting IR absorption in the range of from about 800 to about 1000 nm.