Compounds of formula (I):wherein:A, R, T, Q, L, Z, G, X and A are as defined in the description.B and D, equal to or different from each other, are selected between heteroaryl and aryl, wherein at least one of the hydrogen atoms of said heteroaryl and aryl are substituted with groups selected from SO3-, SO3H, COO-, COOH, and one or more of the other hydrogen atoms of said heteroaryl and aryl are optionally substituted as reported in the description.