A compound of formula I or mesomers thereof: wherein CI is a charge balancing counterion and p is an integer from 1-7; m is 1, 3, 5, 7, or 9; each incidence of X is independently hydrogen, halogen, alkyl- or aryloxy, alkyl- or arylthio, amino- or substituted amino, aryl or alkyl, any of which may be optionally substituted with a substituent selected from carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide, hydroxyl, amino, alkyl- or aryl- amino, dialkyl(aryl)amino, alkoxy, aryloxy, alkyl- or arylthio and halogen; optionally, one or more X groups are combined to form a cyclic ring; Y is independently selected from O, NR a, S, Se, CR b =CR c or CR 2 R 3; Z is independently selected from O, NR a, S, Se, CR b =CR c or CR 4 R 5; wherein R a, R b, R c, R 2, R 3, R 4, and R 5 are independently selected from hydrogen, halogen, alkyl- or aryloxy, alkyl- or arylthio, amino- or substituted amino, alkyl, aryl or substituted alkyl, or substituted aryl; optionally carboxyaryl or sulfoaryl; R 1 is selected from aryl or alkyl, any of which may be optionally substituted with at least one substituent selected from carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide or substituted sulfonamide, hydroxyl, amino, alkyl(aryl)amino, dialkyl(aryl)amino, alkoxy, halogen, succinimidyl ester, ester, and amide or substituted amide; R 6, R 7, R 8, R 9, R 10, R 11, R 12, R 13, R 14, R 15, R 16, R 17, and R 18 are independently selected from hydrogen, carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide, hydroxyl, amino, alkylamino, dialkylamino, alkoxy, halogen, alkyl succinimidyl ester, ester, amide, or any ortho -disposed pair of R 6, R 7, R 8, R 9, R 10, R 11, R 12, R 13, R 14, R 15, R 16, R 17, and R 18 is combined to form a further fused aromatic or heterocyclic ring that is optionally substituted; wherein at least one of R 14, R 15, R 16, R 17, or R 18 is sulfonate or a further fused ring derived from R 14, R 15, R 16, R 17, or R 18 comprises at least one sulfonate substituent; with the proviso that none of R 14, R 15, R 16, R 17, and R 18 are carboxyl. CI is a charge balancing counterion and p is an integer from 1-7; m is 1, 3, 5, 7, or 9; each incidence of X is independently hydrogen, halogen, alkyl- or aryloxy, alkyl- or arylthio, amino- or substituted amino, aryl or alkyl, any of which may be optionally substituted with a substituent selected from carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide, hydroxyl, amino, alkyl- or aryl- amino, dialkyl(aryl)amino, alkoxy, aryloxy, alkyl- or arylthio and halogen; optionally, one or more X groups are combined to form a cyclic ring; Y is independently selected from O, NR a, S, Se, CR b =CR c or CR 2 R 3; Z is independently selected from O, NR a, S, Se, CR b =CR c or CR 4 R 5; wherein R a, R b, R c, R 2, R 3, R 4, and R 5 are independently selected from hydrogen, halogen, alkyl- or aryloxy, alkyl- or arylthio, amino- or substituted amino, alkyl, aryl or substituted alkyl, or substituted aryl; optionally carboxyaryl or sulfoaryl; R 1 is selected from aryl or alkyl, any of which may be optionally substituted with at least one substituent selected from carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide or substituted sulfonamide, hydroxyl, amino, alkyl(aryl)amino, dialkyl(aryl)amino, alkoxy, halogen, succinimidyl ester, ester, and amide or substituted amide; R 6, R 7, R 8, R 9, R 10, R 11, R 12, R 13, R 14, R 15, R 16, R 17, and R 18 are independently selected from hydrogen, carboxyl, sulfonate, sulfinate, sulfoxide, sulfone, sulfonamide, hydroxyl, amino, alkylamino, dialkylamino, alkoxy, halogen, alkyl succinimidyl ester, ester, amide, or any ortho -disposed pair of R 6, R 7, R 8, R 9, R 10, R 11, R 12, R 13, R 14, R 15, R 16, R 17, and R 18 is combined to form a further fused aromatic or heterocyclic ring that is optionally substituted; wherein at least one of R 14, R 15, R 16, R 17, or R 18 is sulfonate or a further fused ring derived from R 14, R 15, R 16, R 17, or R 18 comprises at least one sulfonate substituent; with the proviso that none of R 14, R 15, R 16, R 17, and R 18 are carboxyl.