Modified Indigo Compounds and Methods of Dyeing a Substrate Using a Modified Indigo Compound

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 is 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(1-naphthylacetyl)-2,2′-bi-indolinylidene-3,3′-dione;

(xiii) N,N′-bis(2-phenylbutyryl)-2,2′-indolinylidene-3,3′-dione;

(xiv) (E)-1,1′-di(adamantane-1-carbonyl)-[2,2′-biindolinylidene]-3,3′-dione.

(xv) 1H,1′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(1-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(1-adamantylcarbonyloxy)-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 claim 1 , 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 , wherein the substituent is on one or more carbon atoms.

7 . The dye compound of claim 4 , wherein the substituent is on one or both oxygen atoms.

8 . The dye compound of any one of claim 4 , wherein the substituent is an alkyl, cycloalkyl, alkoxy, halide, acyl, amine, ester, amide, aryl, heteroaryl, heterocyclyl, sulfonate, carbamate, urea, imine, oxime, anhydride, CN, NO 2 , mesylate, or tosylate, wherein each is optionally substituted.

9 . The dye compound of claim 1 , wherein the reducing agent is sodium hydrosulfite, formamidine sulfinic acid, glucose, sodium borohydride, sodium metabisulfite, thiourea dioxide, cellobiose, glyceraldehyde, or fructose.

10 . The compound of claim 1 , which converts to indigo through hydrolysis, such as using a hydrolyzing agent, heat, steam, or combinations thereof.

11 . The compound of claim 1 , which is substantially stable in the presence of oxygen such as in aqueous solutions.

12 . The compound of claim 1 , which has greater water solubility than indigo.

13 . A composition comprising (i) a compound of claim 1 and (ii) water.

14 . The composition of claim 13 , 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.

15 . A kit comprising:

(i) one or more compound of claim 1 ; and

(ii) a reagent and/or device that converts the compound to indigo.

16 . The kit of claim 15 , wherein reagent (ii) comprises a base, a device that generates heat, or a device that generates steam.

17 . A method of preparing a bath for dyeing a substrate, comprising mixing a compound of claim 1 with water.

18 . A compound which is of Formula (I) or (II):

wherein:

R 1 and R 2 are, independently, H, SO 3 R C , SO 2 R C , PO 3 (R C ) 2 , C(O)NR A R B , C(O)-(optionally substituted C 1-6 alkyl), C(O)-(optionally substituted aryl), C(O)-(optionally substituted C 1-9 glycolyl), C(O)-(optionally substituted heteroaryl), C(O)-(optionally substituted heterocyclyl), C(O)-(optionally substituted C 1-6 hydroxyalkyl), C(O)O-(optionally substituted C 1-6 alkyl), C(O)O-(optionally substituted aryl), C(O)O-(optionally substituted C 1-9 glycolyl), C(O)O-(optionally substituted C 1-6 hydroxyalkyl), C(O)O-(optionally substituted heteroaryl), C(O)O-(optionally substituted heterocyclyl); or

R 3 and R 4 are, independently, H, halide, optionally substituted C 1-6 alkyl, optionally substituted C 1-6 hydroxyalkyl, optionally substituted C 1-6 alkoxy, optionally substituted aryl, or SO 3 H;

R 7 and R 8 are, independently, H, SO 3 R C , SO 2 R C , PO 3 (R C ) 2 , C(O)NR A R B , C(O)-(optionally substituted C 1-6 alkyl), C(O)-(optionally substituted aryl), C(O)-(optionally substituted C 1-9 glycolyl), C(O)-(optionally substituted C 1-6 hydroxyalkyl), C(O)-(optionally substituted heteroaryl), C(O)-(optionally substituted heterocyclyl), C(O)O-(optionally substituted C 1-6 alkyl), C(O)O-(optionally substituted aryl), C(O)O-(optionally substituted C 1-9 glycolyl), C(O)O-(optionally substituted C 1-6 hydroxyalkyl), C(O)O-(optionally substituted heteroaryl), or C(O)O-(optionally substituted heterocyclyl);

R A and R B are, independently, H or optionally substituted C 1-6 alkyl, or optionally substituted aryl;

R C is H, optionally substituted C 1-6 alkyl, optionally substituted C 3-8 cycloalkyl, optionally substituted aryl, optionally substituted heteroaryl, or optionally substituted heterocyclyl;

m and n are, independently, 0 to 4;

or a salt thereof.

19 . A method of dyeing a substrate, comprising:

(i) contacting the substrate with an aqueous bath comprising a 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; and

(ii) hydrolyzing the compound of step (i).

20 . A dyed substrate prepared according to the method of claim 19 .