| abstract |
A compound of formula (I) or mesomeric forms thereof: ** (See formula) ** wherein mCat + or mAn- is an organic or inorganic positive / negatively charged counterion and m is an integer of 0-3; p is an integer of 1-2; q is an integer from 1-5; alk is a chain of 1-5 carbon atoms optionally containing one or more double or triple bonds; Cast; Z is OH; n is 1, - X is OH or O- or an ester or amide conjugate thereof; each of Ra1 and Ra2 is independently H, SO3-, sulfonamide, halogen, or an additional ring fused to an adjacent carbon atom; and each of Rc1 and Rc2 is independently alkyl or substituted alkyl, wherein at least one of Ra1 or Ra2 is SO3- or Ra1 or Ra2 is an additional ring fused to an adjacent carbon atom, the additional ring has a SO3-, or Rc1 or Rc2 is an alkylsulfonic acid group. |