Patent ID: 7947256

Claim:
A compound of the following structural formula: T-F, wherein, T is selected from the group consisting of F is represented by the following structural formula (2): or a salt thereof, wherein: X is independently selected from the group consisting of C(CH 2 Y 1 )(CH 2 Y 2 ), O, S, and Se; Y 1 and Y 2 are independently selected from the group consisting of H, C 1 -C 20 aliphatic group and a C 1 -C 20 aliphatic group substituted with —OR*, N(R*) 2 or —SR*, wherein each R* is independently —H or C 1-20 alkyl; W represents a benzo-condensed, a naphtho-condensed or a pyrido-condensed ring; R 1 is selected from the group consisting of (CH 2 ) x CH 3 , (CH 2 ) n SO 3 − and (CH 2 ) n SO 3 H, wherein x is an integer selected from 0 to 6 and n is an integer selected from 2 to 6; R 4 is selected from the group consisting of (CH 2 ) x CH 3 , (CH 2 ) n SO 3 − and (CH 2 ) n SO 3 H, wherein x is an integer selected from 0 to 6 and n is an integer selected from 2 to 6; R 2 and R 3 are independently selected from the group consisting of H, carboxylate, carboxylic acid, carboxylic ester, amine, amide, sulfonamide, hydroxyl, alkoxyl, a sulphonic acid moiety and a sulphonate moiety; Q is selected from the group consisting of a heteroaryl ring substituted with a carboxyl group and a 6-membered heteroaryl ring substituted with a carbonyl group.