Patent ID: 8809551

Claim:
A compound of formula (I) or mesomeric forms thereof: wherein mCat+ or mAn− is an organic or inorganic positively/negatively charged counterion and m is an integer 0-3; each of Ra 1 and Ra 2 is independently H, SO 3 − , sulfonamide, halogen, or a further ring fused to an adjacent carbon atom; Rb is optionally substituted aryl or optionally substituted alkyl; each of Rc 1 and Rc 2 is independently alkyl or substituted alkyl; and either Rb or one of Rc 1 or Rc 2 contains a linking moiety for further attachment or is linked to a further molecule; with the proviso that Rb is not unsubstituted phenyl when the compound is not linked via said linking moiety to a further molecule.