Patent ID: 8481752

Claim:
A compound of Formula I: wherein R 1 is sulfonato; r is 2, 3, or 4; R 3 , R 4 , R 5 , and R 6 are each a member independently selected from the group consisting of hydrogen, alkyl, halo, alkoxy, sulfonato, alkoxyalkyl, and sulfonatoalkyl; or, alternatively, R 5 and R 6 , together with a pair of atoms to which they are bonded, join to form an aryl ring, wherein each said aryl ring is additionally substituted with from 1 to 2 R 14 ; R 8 , R 10 , R 11 , and R 12 are each a member independently selected from the group consisting of hydrogen, alkyl, halo, alkoxy, and sulfonato; each R 14 is a member independently selected from the group consisting of alkyl, halo, hydroxyl, alkoxy, amino, carboxyl, and sulfonato; t is an integer from 1 to 10; R 16 is carboxyl, maleimidyl, alkynyl, azido, or activated acyl; wherein at least one substituent that is selected from the group consisting of R 3 , R 4 , R 5 , R 6 , and R 14 is sulfonato; and wherein said compound has a balanced charge.