Patent ID: 7256292

Claim:
A compound having a structure selected from wherein R 1 -R 3 and R 6 -R 16 are each independently selected from —H, halogen, heteroaryl, —CO 2 H, —CO 2 R, —SO 3 H, —SO 3 R, —CH 2 CO 2 H, —CH 2 CO 2 R, —CH 2 SO 3 H, —CH 2 SO 3 R, —CH 2 NH 2 , —CH 2 NHR, —NO 2 , C 1 -C 6 alkyl, substituted C 1 -C 6 alkyl, C 1 -C 6 alkoxy, substituted C 1 -C 6 alkoxy, C 1 -C 6 alkoxyaryl, substituted C 1 -C 6 alkoxyaryl, phenyl, substituted phenyl, biphenyl, substituted biphenyl, benzyl, substituted benzyl, benzoyl, substituted benzoyl, wherein R is selected from C 1 -C 6 alkyl, substituted C 1 -C 6 alkyl, C 1 -C 6 alkoxy, substituted C 1 -C 6 alkoxy, C 1 -C 6 alkoxyaryl, substituted C 1 -C 6 alkoxyaryl, phenyl, substituted phenyl, biphenyl, substituted biphenyl, benzyl, substituted benzyl, benzoyl, and substituted benzoyl; and R 4 and R 5 taken separately are selected from C 1 -C 6 alkyl and C 1 -C 6 substituted alkyl, R 4 and R 5 taken together are selected from C 3 -C 7 cycloalkyl, C 4 -C 7 unsaturated cycloalkyl, C 3 -C 7 substituted cycloalkyl and C 4 -C 7 substituted unsaturated cycloalkyl; wherein or and R 6 -R 16 is —SO 3 H; with the proviso that if the compound comprises the structure (I), then at least one of R 1 , R 2 , R 3 or R 8 is not —H.