A compound of Formula Ia or Ib: wherein: X is O, S, or -C(CH 3) 2 -; A is -OR 1 or -NR 1 R 1a; B is =O or =N + R 4 R 4a; C is -OR 4 or -NR 4 R 4a; R 1, R 1a, R 4, and R 4a are each independently H or alkyl, unsubstituted or substituted with -L-SO 3 -, -L-PO 3 2-, a water-soluble polymer, or with -L-R x; or one or more pair of R 1 and R 1a or R 4 and R 4a together with the nitrogen to which they are attached form a saturated or unsaturated ring optionally substituted by any of -L-SO 3 -, -L-PO 3 2- and -L-R x; R 2, R 3, R 5, R 6, R 7, R 8, and R 9 are each independently H, halogen, CN, alkyl, alkenyl, alkoxy, alkylthio, alkylamino, dialkylamino, alkylaminocarbonyl, dialkylaminocarbonyl, aryl, heteroaryl, -L-PO 3 2-, L-SO 3 -, -L-R x, or a sulfonamide; or one or more pair of R 2 and R 1a, R 3 and R 4a, R 4 and R 5, R 5 and R 6, R 8 and R 9, or R 9 and R 1, together with the atoms to which they are attached form one or more fused saturated or unsaturated rings that are optionally substituted by at least one halogen, CN, alkyl, heteroalkyl, alkenyl, alkoxy, alkylthio, alkylamino, dialkylamino, alkylaminocarbonyl, dialkylaminocarbonyl, aryl, heteroaryl, -L-PO 3 2-, L-SO 3 -, -L-R x, or a sulfonamide; R 7 ' is H, OH, CN, or C 1 -C 6 alkoxy; or R 7 ' in combination with R 7 forms a 5- or 6-membered spirolactone or spirosultone ring; R x is an isothiocyanate, an isocyanate, a monochlorotriazine, a dichlorotriazine, a halogen-substituted pyridine, a halogen-substituted diazine, a phosphoramidite, a maleimide, an aziridine, a sulfonyl halide, an acid halide, a hydroxysuccinimidyl ester, a hydroxysulfosuccinimidyl ester, a pyrrole-2,5-dione, a tetrafluorophenol ester, an imido ester, a hydrazine, an azidonitrophenyl, an azide, an alkyne, a 3-(2-pyridyl dithio)-propionamide, a glyoxal or an aldehyde; L is a bond or n; each Q is independently NR d, S t, O, C(=X'), substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, or substituted or unsubstituted heterocycloalkyl, wherein t is 0-2, and no more than two NR d are adjacent and no two O are adjacent; each X' is independently NR d, S or O; n is 1-20; each R d is H, substituted or unsubstituted alkyl; provided that at least R 2 is a sulfonamide of Formula IIa: wherein: R 10 is H or a substituted or unsubstituted C 1 -C 12 alkyl; or R 10 and L together with the nitrogen to which they are attached form a saturated or unsaturated ring. X is O, S, or -C(CH 3) 2 -; A is -OR 1 or -NR 1 R 1a; B is =O or =N + R 4 R 4a; C is -OR 4 or -NR 4 R 4a; R 1, R 1a, R 4, and R 4a are each independently H or alkyl, unsubstituted or substituted with -L-SO 3 -, -L-PO 3 2-, a water-soluble polymer, or with -L-R x; or one or more pair of R 1 and R 1a or R 4 and R 4a together with the nitrogen to which they are attached form a saturated or unsaturated ring optionally substituted by any of -L-SO 3 -, -L-PO 3 2- and -L-R x; R 2, R 3, R 5, R 6, R 7, R 8, and R 9 are each independently H, halogen, CN, alkyl, alkenyl, alkoxy, alkylthio, alkylamino, dialkylamino, alkylaminocarbonyl, dialkylaminocarbonyl, aryl, heteroaryl, -L-PO 3 2-, L-SO 3 -, -L-R x, or a sulfonamide; or one or more pair of R 2 and R 1a, R 3 and R 4a, R 4 and R 5, R 5 and R 6, R 8 and R 9, or R 9 and R 1, together with the atoms to which they are attached form one or more fused saturated or unsaturated rings that are optionally substituted by at least one halogen, CN, alkyl, heteroalkyl, alkenyl, alkoxy, alkylthio, alkylamino, dialkylamino, alkylaminocarbonyl, dialkylaminocarbonyl, aryl, heteroaryl, -L-PO 3 2-, L-SO 3 -, -L-R x, or a sulfonamide; R 7 ' is H, OH, CN, or C 1 -C 6 alkoxy; or R 7 ' in combination with R 7 forms a 5- or 6-membered spirolactone or spirosultone ring; R x is an isothiocyanate, an isocyanate, a monochlorotriazine, a dichlorotriazine, a halogen-substituted pyridine, a halogen-substituted diazine, a phosphoramidite, a maleimide, an aziridine, a sulfonyl halide, an acid halide, a hydroxysuccinimidyl ester, a hydroxysulfosuccinimidyl ester, a pyrrole-2,5-dione, a tetrafluorophenol ester, an imido ester, a hydrazine, an azidonitrophenyl, an azide, an alkyne, a 3-(2-pyridyl dithio)-propionamide, a glyoxal or an aldehyde; L is a bond or n; each Q is independently NR d, S t, O, C(=X'), substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, or substituted or unsubstituted heterocycloalkyl, wherein t is 0-2, and no more than two NR d are adjacent and no two O are adjacent; each X' is independently NR d, S or O; n is 1-20; each R d is H, substituted or unsubstituted alkyl; provided that at least R 2 is a sulfonamide of Formula IIa: R 10 is H or a substituted or unsubstituted C 1 -C 12 alkyl; or R 10 and L together with the nitrogen to which they are attached form a saturated or unsaturated ring.