1. A dye compound for use in dyeing a substrate, the dye compound comprising an indigo derivative, or a salt thereof, having one or more modification over the chemical structure of indigo, wherein the indigo derivative has a water-solubility of greater than 0.2% w/v in the absence of a reducing agent and in the presence oxygen, and converts to indigo upon removing the modification, wherein the chemical structure of indigo js the following:
2. The dye compound of claim 1, wherein the dye compound is not:
(i) N,N'-dinicotinoyl-[2,2'-biindolinylidene]-3,3'-dione;
(i) the N",N'"-methylpyridinium bis(methylsulfate) salt of N,N'-dinicotinoyl-[2,2'-
biindolinylidene]-3,3'-dione;
(iii) N,N'-diacetyl-[2,2'-biindolinylidene]-3,3'-dione;
(iv) N,N'-dipropionyl-[2,2'-bi-indolinylidene]-3,3'-dione;
(v) N,N'-di-isobutyryl-[2,2'-biindolinylidene]-3,3'-dione;
(vi) N,N'-dipivaloyl-[2,2'-biindolinylidene]-3,3'-dione;
(vii) N,N'-bis(cyclohexylcarbonyl)-2,2'-bi-indolinylidene-3,3'-dione;
(viii) N,N'-bis(3-phenylpropionyl)-2,2'-bi-indolinylidene-3,3'-dione;
(ix) N,N'-bis(ethoxycarbonylacetyl)-2,2'-bi-indolinylidene-3,3'-dione;
(x) N,N'-bis(2-phenylacetyl)-[2,2'-bi-indolinylidene]-3,3'-dione;
(xi) N,N'-bis-(p-methoxyphenylacetyl)2,2'-bi-indolinylidene-3,3'-dione;
(xii) N,N'-bis(l-naphthylacetyl)-2,2'-bi-indolinylidene-3,3'-dione;
(xiii) N,N'-bis(2-phenylbutyryl)-2,2'-indolinylidene-3,3'-dione;
(xiv) (E)-l,l'-di(adamantane-l-carbonyl)-[2,2'-biindolinylidene]-3,3'-dione.
(xv) lH,l'H-[2,2'-biindole]-3,3'-diyl diacetate;
(xvi) 3,3 '-bis(phenylacetoxy)-2,2'-bi-indolyl;
(xvii) 3,3'-bis(p-methoxyphenylacetoxy)-2,2'-bi-indolyl;
(xviii) 3,3'-bis(l-napthylacetoxy)-2,2'-bi-indolyl;
(xix) 3,3'-bis(phenylbutyryloxy)-2,2'-bi-indolyl;
(xx) 3,3'-bis(pivaloyloxy)-2,2'-bi-indolyl;
(xxi) 3,3'-bis(l-adamantylcarbonyIoxy)-2,2'-bi-indolyl; or

(xxii) 3,3'-bis(ethoxycarbonylacetoxy)-2,2'-bi-indolyl.
3. The dye compound of claim 1, wherein the one or more modification enhances the aqueous solubility of the dye compound lacking the modification.
4. The dye compound of any one of the preceding claims, wherein the one or more modification is a substituent on indigo or the indigo derivative.
5. The dye compound of claim 4, wherein the substituent is on one or both nitrogen atoms.
6. The dye compound of claim 4 or 5, wherein the substituent is on one or more carbon atom.
7. The dye compound of any one of claims 4-6, wherein the substituent is on one more both oxygen atoms.
8. The dye compound of any one of claims 4-7, wherein the substituent is an alkyl, cycloalkyl, alkoxy, halide, acyl, amine, ester, amide, aryl, heteroaryl, heterocyclyl, sulfonate, carbamate, urea, imine, oxime, anhydride, CN, NO2, mesylate, or tosylate, wherein each is optionally substituted.
9. The dye compound of any one of claims 1-8, wherein the reducing agent is sodium hydrosulfite, formamidine sulfinic acid, glucose, sodium borohydride, sodium metabisulfite, thiourea dioxide, cellobiose, glyceraldehyde, or fructose.
10. A compound which is of Formula (I) or (II):
wherein:
R1 and R2 are, independently, H, S03Rc, S02Rc, P03(Rc)2, C(0)NRARB, C(O)-(optionally substituted d-6alkyl), C(0)-(optionally substituted aryl), C(0)-(optionally

substituted Ci.9glycolyl), C(0)-(optionally substituted heteroaryl), C(0)-(optionally substituted heterocyclyl), C(0)-(optionally substituted Ci_6hydroxyalkyl), C(0)0-(optionally substituted Ci-6alkyi), C(0)0-(optionally substituted aryl), C(0)0-(optionally substituted Ci_9glycolyl), C(0)0-(optionally substituted Ci. 6hydroxyalkyl), C(0)0-(optionally substituted heteroaryl), C(0)0-(optionally substituted heterocyclyl); or R3 and R4 are, independently, H, halide, optionally substituted 'Ci^alkyl, optionally substituted C^hydroxyalky 1, optionally substituted C^alkoxy, optionally substituted aryl, or SO3H; R7 and R8 are, independently, H, S03Rc, S02Rc, P03(Rc)2, C(0)NRARB, C(O)-(optionally substituted Ci_6alkyl), C(0)-(optionally substituted aryl), C(0)-(optionally substituted Ci_9glycolyl), C(0)-(optionally substituted Ci„6hydroxyalkyl), C(O)-(optionally substituted heteroaryl), C(0)-(optionally substituted heterocyclyl), C(0)0-(optionally substituted Ci^alkyl), C(0)0-(optionally substituted aryl), C(0)0-(optionally substituted Ci_9glycolyl), C(0)0-(optionally substituted Ci_ 6hydroxyalkyl), C(0)0-(optionally substituted heteroaryl), or C(0)0-(optionally substituted heterocyclyl); RA and RB are, independently, H or optionally substituted Ci_6alkyl, or optionally
substituted aryl; Rc is H, optionally substituted Ci_6alkyl, optionally substituted C3-scycloalkyl,
optionally substituted aryl, optionally substituted heteroaryl, or optionally
substituted heterocyclyl; m and n are, independently, 0 to 4; or a salt thereof.
11. The compound of claim 10, wherein when the compound is of Formula (I), R and R are not H, when R1 and R2 are both l-mefhyl-pyridyl-3-yl.
12. The compound of claim 10 or 11, wherein m is 0.
13. The compound of any one of claims 10-12, wherein n is 0.
14. The compound of claim 10 or 11, wherein R3 is a halide.
15. The compound of any one of claims 10, 11, or 14, wherein R4 is a halide.
16. The compound of any one of claims 10, 11, or 15, wherein R3 is Ci_6alkyl.

17. The compound of any one of claims 10, 11, 14, or 16, wherein R4 is Ci_6alkyl.
18. The compound of any one of claims 10-17, wherein one ofR'orRMsH.
19. The compound of any one of claims 10-18, wherein one ofR'andR2isS03H.
20. The compound of any one of claims 10-19 which is of Formula (I):

21. The compound of any one of claims 10-20, wherein one or bothofR'andR2isC(0)-(optionally substituted heteroaryl).
22. The compound of any one of claims 10-21, wherein one or both of R1 and R2 is C(O)-(optionally substituted pyridyl), such as C(0)-(optionally substituted 2-pyridyl), C(O)-(optionally substituted 3-pyridyl), or C(0)-(optionally substituted 4-pyridyl).
23. The compound of claim 22, wherein the pyridyl is substituted with Ci_6alkyl.
24. The compound of claim 22 or 23, wherein the pyridyl is substituted with one or more methyl or ethyl.
25. The compound of any one of claims 22-24, wherein the pyridyl is substituted on the N-atom.
26. The compound of any one of claims 10-20, wherein one or both of R1 and R2 is C(O)-(optionally substituted aryl), such as C(0)-(optionally substituted phenyl).
27. The compound of any one of claims 10-20, wherein one or both of R1 and R2 is C(0)NRARB, wherein one or both of RA and RB is H, optionally substituted Q. 6hydroxyalkyl, or optionally substituted Cj^alkyl.
28. The compound of any one of claims 10-20, wherein one or both of R1 and R2 are C(0)0-(optionally substituted heterocyclyl) such as C(0)0-(optionally substituted pyrrolidone).

29. The compound of any one of claims 10-20, wherein one or both of R1 and R2 are, independently, C(0)0-(optionally substituted alkyl) such as C(0)0(alkyl substituted with heterocyclyl) such as C(0)0(alkyl substituted with glucosyl).
30. The compound of any one of claims 10-20, wherein one or both of R1 and R2 are, independently, C(0)(optionally substituted Ci^hydroxyalkyl).
31. The compound of any one of claims 10-20, wherein one or both of R1 and R2 are, independently, C(0)0(optionally substituted Ci-6hydroxyalkyl).
32. The compound of any one of claims 10-20, wherein one or both of R1 and R2 are, independently, C(0)(optionally substituted Ci-9glycol).
33. The compound of any one of claims 10-19 which is of Formula (II):
34. The compound of claim 33, wherein one or both of R1 and R2 are H.
7 8
35. The compound of claim 33 or 34, wherein one or both of R and R are H.
36. The compound of claim 33 or 34, wherein one of R7 and R8 are SO3H.
37. The compound of claim 33 or 34, wherein one or both of R7 and R8 are C(0)(optionally substituted heteroaryl) such as C(0)(optionally substituted pyridyl).
38. The compound of claim 33 or 34, wherein one or both of R7 and R8 are C(0)(optionally substituted Ci^alkyl).
39. The compound of claim 38, wherein the Ci_6alkyl is substituted with C(0)0(Ci^alkyl) such as C(0)OCH2CH3.
40. The compound of claim 33 or 34, wherein one or both of R7 and R8 are C(0)-(optionally substituted aryl) such as C(0)-(optionally substituted phenyl).
41. The compound of claim 40, wherein the phenyl is substituted with CO2H.

42. The compound of any one of the preceding claims which is an acid or base addition salt.
43. The compound of any one of the preceding claims, which is a sulfate salt, alkylsulfate salt, bisulfate salt, phosphate salt, or halide salt.
44. The compound of claim 43, wherein the halide salt is an iodide salt, chloride salt, bromide salt, or fluoride salt.
45. The compound of claim 43, which is an alkylsulfate salt.
46. The compound of claim 45, which is a methylsulfate or ethylsulfate salt.
47. The compound of claim 10 or 11, which is of Formula (IA):
R5 and R6 are, independently, H or Ci^alkyl; and X is halide, sulfate, Ci^alkylsulfate, bisulfate, or phosphate; with the proviso that both R5 and R6 are not CH3 when X is CH3SO4".

59. The compound of claim 10, that is not:
N,N'-dinicotinoyl-[2,2'-biindolinylidene]-3,3'-dione;
the N",N'"-methylpyridinium bis(methylsulfate) salt of N,N'-dinicotinoyl-[2,2'-
biindolinylidene]-3,3'-dione; N,N'-diacetyl-[2,2'-biindolinylidene]-3,3'-dione; N,N'-dipropionyl-[2,2'-bi-indolinylidene]-3,3'-dione; N,N'-di-isobutyryl-[2,2'-biindolinylidene]-3,3'-dione; N,N'-dipivaloyl-[2,2'-biindolinylidene]-3,3'-dione; N,N'-bis(cyclohexylcarbonyl)-2,2'-bi-indolinylidene-3,3'-dione; N,N'-bis(3-phenylpropionyl)-2,2'-bi-indolinylidene-3,3'-dione; N,N'-bis(ethoxycarbonylacetyl)-2,2'-bi-indolinylidene-3,3'-dione; N,N'-bis(2-phenylacetyl)-[2,2'-bi-indolinylidene]-3,3'-dione; N,N'-bis-(p-methoxyphenylacetyl)2,2'-bi-indolinylidene-3,3'-dione; N,N'-bis(l-naphthylacetyl)-2,2'-bi-indolinylidene-3,3'-dione; N,N'-bis(2-phenylbutyryl)-2,2'-indolinylidene-3,3'-dione; (E)-l,r-di(adamantane-l-carbonyl)-[2,2'-biindolinylidene]-3,3'-dione; lH,l'H-[2,2'-biindole]-3,3'-diyldiacetate; 3,3'-bis(phenylacetoxy)-2,2'-bi-indolyl; 3,3'-bis(p-methoxyphenylacetoxy)-2,2'-bi-indolyl; 3,3'-bis(l-napthylacetoxy)-2,2'-bi-indolyl; 3,3'-bis(phenylbutyryloxy)-2,2'-bi-indolyl; 3,3'-bis(pivaloyloxy)-2,2'-bi-indolyl;

3,3'-bis(l-adamantylcarbonyloxy)-2,2'-bi-indolyl; or 3,3'-bis(ethoxycarbonylacetoxy)-2,2'-bi-indolyl.
60. The compound of any one of the preceding claims, which converts to indigo through hydrolysis, such as using a hydrolyzing agent, heat, steam, or combinations thereof.
61. The compound of any one of the preceding claims, which is substantially stable in the presence of oxygen such as in aqueous solutions.
62. The compound of any one of the preceding claims, which has greater water solubility than indigo.
63. A composition comprising (i) a compound of any one of the preceding claims and (ii) water.
64. The composition of claim 63, further comprising one or more of an acid, cationic agent, chelating agent, color retention agent, coloring agent, dispersant, foaming agent, mercerization reagent, penetration enhancer, pH buffering agent, salt, solubilizing agent, stabilizing agent, surfactant, thickening agent, tracer, viscosity modifier, or wetting agent.
65. A kit comprising:
(i) one or more compound of any one of claims 1-62; and
(ii) a reagent and/or device that converts the compound to indigo.
66. The kit of claim 65, wherein reagent (ii) comprises a base, a device that generates heat, or a device that generates steam.
67. A method of preparing a bath for dyeing a substrate, comprising mixing a compound of any one of claims 1-62 with water.
68. The method of claim 67, wherein the water is acidic.
69. The method of claim 67 or 68, wherein the water further comprises one or more additional components.
70. The method of claim 69, wherein said additional component is an acid, cationic agent, caustic agent, chelating agent, color retention agent, coloring agent, dispersant, foaming agent, hydrolyzing agent, mercerization reagent, penetration enhancer, pH buffering

agent, salt, solubilizing agent, stabilizing agent, surfactant, thickening agent, tracer, viscosity modifier, or wetting agent.
71. A method of dyeing a substrate, comprising:
(i) contacting the substrate with an aqueous bath comprising a compound of any one
of claims 1-62; and (ii) hydrolyzing the compound of step (i).
72. A method of dyeing a natural substrate such as a plant fiber such as cotton, kapok, hemp,
bamboo, flax, sisal, jute, kenaf, ramie, bamboo, soybean, or coconut or an animal
substrate such as silk, wool, leather, or feather or a synthetic substrate, comprising:
(i) contacting the substrate with an aqueous bath comprising one or more of a compound of any one of claims 1-62 or one of the following:
N,N'-dinicotinoyl-[2,2'-biindolinylidene]-3,3'-dione;
the N",N'"-methylpyridinium bis(methylsulfate) salt of N,N'-dinicotinoyl-[2,2'-biindolinylidene]-3,3'-dione;
N,N'-diacetyl-[2,2'-biindolinylidene]-3,3'-dione;
N,N'-dipropionyl-[2,2'-bi-indolinylidene]-3,3'-dione;
N,N'-di-isobutyryl-[2,2'-biindolinylidene]-3,3'-dione;
N,N'-dipivaloyl-[2,2'-biindolinylidene]-3,3'-dione;
N,N'-bis(cyclohexylcarbonyl)-2,2'-bi-indolinylidene-3,3'-dione;
N,N'-bis(3-phenylpropionyl)-2,2'-bi-indolinylidene-3,3'-dione;
N,N'-bis(ethoxycarbonylacetyl)-2,2'-bi-indolinylidene-3,3'-dione;
N,N'-bis(2-phenylacetyl)-[2,2'-bi-indolinylidene]-3,3'-dione;
N,N'-bis-(p-methoxyphenylacetyl)2,2'-bi-indolinylidene-3,3'-dione;
N,N'-bis(l-naphthylacetyl)-2,2'-bi-indolinylidene-3,3'-dione;
N,N'-bis(2-phenylbutyryl)-2,2'-indolinylidene-3,3'-dione;
(E)-l,l'-di(adamantane-l-carbonyl)-[2,2'-biindolinylidene]-3,3'-dione; 1H,1'H-[2,2'-biindole]-3,3'-diyl diacetate;
3,3'-bis(phenylacetoxy)-2,2'-bi-indolyl;
3,3'-bis(p-methoxyphenylacetoxy)-2,2'-bi-indolyl;
3,3'-bis(l-napthylacetoxy)-2,2'-bi-indolyl;
3,3'-bis(phenylbutyryloxy)-2,2'-bi-indolyl;
3,3'-bis(pivaloyloxy)-2,2'-bi-indolyl;
3,3 '-bis( 1 -adamantylcarbonyloxy)-2,2'-bi-indolyl; or

3,3'-bis(ethoxycarbonylacetoxy)-2,2'-bi-indolyl; and (ii) hydrolyzing the compound of step (i).
73. The method of claim 71 or 72, further comprising repeating steps (i) and (ii).
74. The method of any one of claims 71-73, wherein the aqueous bath further comprises a stabilizing agent such as NaCl, Na2S04, or combinations thereof.
75. The method of any one of claims 71-74, wherein the hydro lyzing is performed using a base, heat, steam, or a combination thereof.
76. The method of claim 75, wherein the base is a hydroxide base, an alkaline earth base, or a carbonate.
77. The method of claim 75, wherein the base is a hydroxide base that is sodium hydroxide, potassium hydroxide, or lithium hydroxide.
78. The method of claim 75, wherein the base is a carbonate that is sodium carbonate or potassium carbonate.
79. The method of claim 74, wherein heat comprises a temperature of at least about 80°C such as about 80 to about 200°C, such as about 80 to about 100°C, about 80 to about 120°C, about 80 to about 150°C, or about 80 to about 180°C.
80. The method of any one of claims 71-79, further comprising: (iii) rinsing the substrate from step (ii).
81. The method of claim 80, further comprising repeating steps (i) through (iii).
82. The method of claim 80 or 81, wherein rinsing is performed with an aqueous solution.
83. The method of claim 82, wherein the aqueous solution further comprises an organic solvent, acid, cationic agent, caustic agent, chelating agent, color retention agent, coloring agent, dispersant, foaming agent, hydrolyzing agent, mercerization reagent, penetration enhancer, pH buffering agent, salt, solubilizing agent, surfactant, thickening agent, tracer, viscosity modifier, or wetting agent.
84. The method of claim 82 or 83, wherein the aqueous solution further comprises a neutralization agent or buffering agent.

85. The method of claim 84, wherein the pH of the dyed substrate is adjusted to about 5 to about 9.
86. The method of any one of claims 71-85, further comprising:
(iv) pretreating the substrate prior to step (i) with a cationic agent or caustic agent.
87. The method of claim 86, wherein the cationic agent is diallyldimethylammonium chloride, polymerized diallyldimethylammonium chloride, [2-(acryloyloxy)ethyl] trimethylammonium chloride, 3-chloro-2-hydroxylpropyl trimethyl-ammonium chloride, or a combination thereof.
88. The method of claim 86, wherein the caustic agent is sodium hydroxide, potassium hydroxide, sodium carbonate, diethanolamine, trimethylamine, hexamethylenediamine, liquid ammonia, or a combination thereof.
89. The method of any one of claims 71-88, wherein the substrate is a textile.
90. The method of any one of claims 71 or 73-89, wherein the substrate is a natural substrate such as a plant fiber such as cotton, kapok, hemp, bamboo, flax, sisal, jute, kenaf, ramie, bamboo, soybean, or coconut or an animal substrate such as silk, wool, leather, hair, or feather.
91. The method of claim 89, wherein the substrate is a synthetic substrate such as a polyamide such as nylon, polyester, acrylic, polyolefm, or spandex.
92. The method of any one of claims 71-91, wherein the substrate is a yarn.
93. The method of any one of claims 71-91, wherein the substrate is a package of yarn.
94. The method of any one of claims 71-91, wherein the substrate is a fabric.
95. The method of claim 71-91 or 94, wherein the substrate is dyed denim fabric.
96. The method of any one of claims 71-95, wherein the treating comprises dip dyeing, rope dyeing, slasher dyeing, spray dyeing, continuous dyeing, piece dyeing, space dyeing, package dyeing, skein dyeing, garment dyeing, paint brush dyeing, airbrush dyeing, blotch dyeing, or foam dyeing.

97. The method of any one of claims 71-95, wherein the treating comprises screen printing or digital printing.
98. The method of any one of claims 71-96, wherein the bath is a foam and the foam is applied to the textile.
99. The method of any one of claims 71-97, wherein the aqueous bath further comprises one or more of an acid, cationic agent, chelating agent color retention agent, coloring agent, dispersant, foaming agent, mercerization reagent, pH buffering agent, penetration enhancer, salt, stabilizing agent, solubilizing agent, surfactant, thickening agent, tracer, viscosity modifier, or wetting agent.

100. The method of any one of claims 71-99, wherein the aqueous bath lacks a reducing agent to convert the compound to a leuco form of the compound.
101. The method of claim 100, wherein the reducing agent is sodium hydrosulfite, formamidine sulfinic acid, glucose, sodium borohydride, sodium metabisulfite, thiourea dioxide, cellobiose, glyceraldehyde, fructose, or combinations thereof.
102. The method of any one of claims 71-96, wherein the aqueous bath lacks an alkali agent.
103. The method of any one of claims 71-102, wherein the pH of the aqueous bath is less than about 9.
104. The method of any one of claims 71-103, wherein the aqueous bath comprises about 0.5 wt.% to about 70 wt.%, based on the weight of the bath, of the compound.
105. The method of claim 104, wherein the bath comprises about 1 wt.% to about 50 wt.%, based on the weight of the bath, of the compound.
106. The method of claim 105, wherein the bath comprises about 2 wt.% to about 30 wt.%, based on the weight of the bath, of the compound.
107. The method of claim 106, wherein less than about 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5 wt.%) of the compound in an aqueous solution degrades under atmospheric conditions over a period of about 12 hours in the absence of a reducing agent.
108. A dyed substrate prepared according to the methods of any one of claims 71-107.