Patent ID: 7351808

Claim:
A compound of the formula in which A represents a 1- or 2-naphthyl residue, which is substituted by a total of one or two sulphonic and/or carboxylic acid groups, R 1 represents hydrogen each D 1 and D 2, independently of the other, represent either an amino acid residue resulting from removal of a hydrogen atom from the amino group of the amino acid or the residue —NR 2 R 3, in which each R 2 and R 3 , independently of the other, represent hydrogen, C 1 -C 4 alkyl, C 2 -C 6 alkyl which is substituted by hydroxy, halogen or cyano, phenyl which is unsubstituted or monosubstituted by hydroxy, halogen, SO 3 H, C 1 -C 4 alkyl or C 1 -C 4 alkoxy or, alternatively, R 2 and R 3, together with the nitrogen atom to which they are connected, complete a saturated, 5- or 6-membered ring which may contain, in addition to the nitrogen atom, one nitrogen or oxygen atom and which may be further substituted and n is 0 or 1.