Symmetrical diazo compounds comprising 4-pyridinium groups and a cationic or non-cationic linker, compositions comprising them, method for coloring, and device

A dyeing composition comprising, in a medium appropriate for the dyeing of keratin fibers, as direct dye at least one symmetrical cationic diazo compound chosen from compounds of formula (I), their acid addition salts, and their solvates:

• in which:
• the radicals R2, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom, said alkyl radicals being further optionally substituted by at least one group chosen from thio (—SH), C1-C4 thioalkyl;
• C1-C4 alkylsulphinyl, and C1-C4 alkylsulphonyl groups;
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• amino groups,
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group, it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (R″SO2—NR—) in which R″ is chosen from C1-C4 alkyl radicals and R is chosen from hydrogen and C1-C4 alkyl radicals;
• optionally substituted aryl radicals;
• optionally substituted (C1-C4)alkylaryl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• halogen atoms;
• thio groups (HS—);
• and
• alkylthio groups (R″S—) in which the radical R″ is chosen from optionally substituted C1-C4 alkyl radicals;
• when e is 2, the two radicals R2 may optionally form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 5 or 6 ring members which is optionally substituted by at least one identical or non-identical group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, and amino groups, amino substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group;
• e is an integer ranging from 0 to 4;
• wherein when e is less than 4, the one or more unsubstituted carbon atoms of the heterocycle carry a hydrogen atom,
• the radicals R3, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom,
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• amino groups;
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group;
• it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocyle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (RSO2—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• thio groups (HS—);
• alkylthio groups (R″S—) in which the radical R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• and
• halogen atoms;
• when m′ is greater than or equal to 2, two adjacent radicals R3 may form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 6 ring members, which is optionally substituted by at least one identical or different group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, C1-C4 alkylcarbonylamino groups, amino groups, amino groups substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group,
• m′ is an integer ranging from 0 to 4;
• wherein when m′ is less than 4, the one or more unsubstituted carbon atoms of the aromatic ring carry a hydrogen atom;
• the radicals W1, which are identical, are chosen from:
• hydrogen,
• halogen atoms chosen from bromine, chlorine, and fluorine, and
• —NR5R6, OR7, —NR4—Ph—NR5R6, —NR4—Ph—OR7, —O—Ph—OR7, and —O—Ph—NR5R6 groups, wherein:
• R4 and R7, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted C1-C3 aralkyl radicals, and optionally substituted phenyl radicals;
• R5 and R6, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted phenyl radicals, optionally substituted C1-C3 aralkyl radicals, and alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• R5 and R6 may optionally form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O, and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• R5 and R6 may form, together with the carbon atom of the aromatic ring adjacent to that to which —NR5R6 is attached, a 5- or 6-membered saturated heterocycle;
• and
• Ph is chosen from optionally substituted phenyl radicals;
• L is chosen from cationic linkers and non-cationic linkers;
• and
• the electroneutrality of the compound of formula (I) being ensured by at least one identical or non-identical, cosmetically acceptable anion An.

A method for coloring keratin fibers comprising contacting the keratin fibers, which are dry or wet, with a dyeing composition for a time sufficient to give the desired effect, wherein the dyeing composition comprises, in a medium appropriate for the dyeing of keratin fibers, as direct dye at least one symmetrical cationic diazo compound chosen from compounds of formula (I), their acid addition salts, and their solvates:

• in which:
• the radicals R2, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom, said alkyl radicals being further optionally substituted by at least one group chosen from thio (—SH), C1-C4 thioalkyl;
• C1-C4 alkylsulphinyl, and C1-C4 alkylsulphonyl groups;
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• amino groups,
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group, it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (R″SO2—NR—) in which R″ is chosen from C1-C4 alkyl radicals and R is chosen from hydrogen and C1-C4 alkyl radicals;
• optionally substituted aryl radicals;
• optionally substituted (C1-C4)alkylaryl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• halogen atoms;
• thio groups (HS—);
• and
• alkylthio groups (R″S—) in which the radical R″ is chosen from optionally substituted C1-C4 alkyl radicals;
• when e is 2, the two radicals R2 may optionally form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 5 or 6 ring members which is optionally substituted by at least one identical or non-identical group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, and amino groups, amino substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group;
• e is an integer ranging from 0 to 4;
• wherein when e is less than 4, the one or more unsubstituted carbon atoms of the heterocycle carry a hydrogen atom,
• the radicals R3, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom,
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• amino groups;
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group;
• it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocyle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (RSO2—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• thio groups (HS—);
• alkylthio groups (R″S—) in which the radical R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• and
• halogen atoms;
• when m′ is greater than or equal to 2, two adjacent radicals R3 may form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 6 ring members, which is optionally substituted by at least one identical or different group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, C1-C4 alkylcarbonylamino groups, amino groups, amino groups substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group,
• m′ is an integer ranging from 0 to 4;
• wherein when m′ is less than 4, the one or more unsubstituted carbon atoms of the aromatic ring carry a hydrogen atom;
• the radicals W1, which are identical, are chosen from:
• hydrogen,
• halogen atoms chosen from bromine, chlorine, and fluorine, and
• —NR5R6, OR7, —NR4—Ph—NR5R6, —NR4—Ph—OR7, —O—Ph—OR7, and —O-—Ph—NR5R6 groups, wherein:
• R4 and R7, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted C1-C3 aralkyl radicals, and optionally substituted phenyl radicals;
• R5 and R6, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted phenyl radicals, optionally substituted C1-C3 aralkyl radicals, and alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• R5 and R6 may optionally form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O, and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• R5 and R6 may form, together with the carbon atom of the aromatic ring adjacent to that to which —NR5R6 is attached, a 5- or 6-membered saturated heterocycle;
• and
• Ph is chosen from optionally substituted phenyl radicals;
• L is chosen from cationic linkers and non-cationic linkers;
• and
• the electroneutrality of the compound of formula (I) being ensured by at least one identical or non-identical, cosmetically acceptable anion An.

A device having a plurality of compartments, in which a first compartment contains at least one dyeing composition and a second compartment contains at least one oxidizing composition, wherein the dyeing composition comprises, in a medium appropriate for the dyeing of keratin fibers, as direct dye at least one symmetrical cationic diazo compound chosen from compounds of formula (I), their acid addition salts, and their solvates:

• in which:
• the radicals R2, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom, said alkyl radicals being further optionally substituted by at least one group chosen from thio (—SH), C1-C4 thioalkyl;
• C1-C4 alkylsulphinyl, and C1-C4 alkylsulphonyl groups;
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• amino groups,
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group, it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (R″SO2—NR—) in which R″ is chosen from C1-C4 alkyl radicals and R is chosen from hydrogen and C1-C4 alkyl radicals;
• optionally substituted aryl radicals;
• optionally substituted (C1-C4)alkylaryl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• halogen atoms;
• thio groups (HS—);
• and
• alkylthio groups (R″S—) in which the radical R″ is chosen from optionally substituted C1-C4 alkyl radicals;
• when e is 2, the two radicals R2 may optionally form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 5 or 6 ring members which is optionally substituted by at least one identical or non-identical group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, and amino groups, amino substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group;
• e is an integer ranging from 0 to 4;
• wherein when e is less than 4, the one or more unsubstituted carbon atoms of the heterocycle carry a hydrogen atom,
• the radicals R3, which may be identical or different, are independently chosen from:
• optionally substituted C1-C16 alkyl radicals optionally interrupted by at least one entity chosen from heteroatoms and groups comprising at least one heteroatom,
• hydroxyl groups,
• C1-C4 alkoxy groups,
• C2-C4 (poly)hydroxyalkoxy groups;
• alkoxycarbonyl groups (R″O—CO—) in which R″ is chosen from C1-C4 alkyl radicals,
• alkylcarbonyloxy radicals (R″CO—O—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• amino groups;
• amino groups substituted by one or two identical or different C1-C4 alkyl radicals optionally carrying at least one hydroxyl group;
• it being possible for the two alkyl radicals optionally to form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O and S, said heterocyle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• alkylcarbonylamino groups (R″CO—NR—) in which the radical R″ is chosen from C1-C4 alkyl radicals and the radical R is chosen from hydrogen and C1-C4 alkyl radicals;
• aminocarbonyl groups ((R)2N—CO—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• ureido groups (N(R)2—CO—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• aminosulphonyl groups ((R)2N—SO2—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• alkylsulphonylamino groups (RSO2—NR—) in which the radicals R, which may be identical or different, are independently chosen from hydrogen and C1-C4 alkyl radicals;
• thio groups (HS—);
• alkylthio groups (R″S—) in which the radical R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphinyl groups (R″—SO—) in which R″ is chosen from C1-C4 alkyl radicals;
• alkylsulphonyl groups (R″—SO2—) in which R″ is chosen from C1-C4 alkyl radicals;
• nitro groups;
• cyano groups;
• and
• halogen atoms;
• when m′ is greater than or equal to 2, two adjacent radicals R3 may form, together with the carbon atoms to which they are attached, a secondary, aromatic or non-aromatic ring comprising 6 ring members, which is optionally substituted by at least one identical or different group chosen from hydroxyl groups, C1-C4 alkyl groups, C1-C4 alkoxy groups, C2-C4 (poly)hydroxyalkoxy groups, C1-C4 alkylcarbonylamino groups, amino groups, amino groups substituted by one or two identical or different C1-C4 alkyl radicals which optionally carry at least one hydroxyl group,
• m′ is an integer ranging from 0 to 4;
• wherein when m′ is less than 4, the one or more unsubstituted carbon atoms of the aromatic ring carry a hydrogen atom;
• the radicals W1, which are identical, are chosen from:
• hydrogen,
• halogen atoms chosen from bromine, chlorine, and fluorine, and
• —NR5R6, OR7, —NR4—Ph—NR5R6, —NR4—Ph—OR7, —O—Ph—OR7, and —O—Ph—NR5R6 groups, wherein:
• R4 and R7, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted C1-C3 aralkyl radicals, and optionally substituted phenyl radicals;
• R5 and R6, which may be identical or different, are independently chosen from hydrogen, optionally substituted C1-C20 alkyl radicals, optionally substituted phenyl radicals, optionally substituted C1-C3 aralkyl radicals, and alkylcarbonyl radicals (R″—CO—) in which R″ is chosen from C1-C4 alkyl radicals;
• R5 and R6 may optionally form, together with the nitrogen atom to which they are attached, a heterocycle comprising from 1 to 3 heteroatoms, chosen from N, O, and S, said heterocycle comprising from 5 to 7 ring members, and being saturated or unsaturated, aromatic or non-aromatic, and optionally substituted;
• R5 and R6 may form, together with the carbon atom of the aromatic ring adjacent to that to which —NR5R6 is attached, a 5- or 6-membered saturated heterocycle;
• and
• Ph is chosen from optionally substituted phenyl radicals;
• L is chosen from cationic linkers and non-cationic linkers;
• and
• the electroneutrality of the compound of formula (I) being ensured by at least one identical or non-identical, cosmetically acceptable anion An.