Composition and method for bleaching a substrate

A method of treating a textile by contacting the textile with a ligand which forms a complex with a transition metal, whereby the complex catalyses bleaching of the textile by atmospheric oxygen without use of aldehydes, wherein at least 50% of any bleaching of the substrate occurs by oxygen sourced from the air and after the treatment, wherein the ligand is represented by general formula (I), or its protonated or deprotonated analogue:

• wherein
• Z1 groups independently represent a coordinating group selected from hydroxy, amino, —NHR or —N(R)2 (wherein R=C1-6-alkyl), carboxylate, amido, —NH—C(NH)NH2, hydroxyphenyl, a heterocyclic ring optionally substituted by one or more functional groups E or a heteroaromatic ring optionally substituted by one or more functional groups E, the heteroaromatic ring being selected from pyridine, pyrimidine, pyrazine, pyrazole, imidazole, benzimidazole, quinoline, quinoxaline, triazole, isoquinoline, carbazole, indole, isoindole, oxazole and thiazole;
• Q1 and Q3 independently represent a group of the formula:
• wherein
• 5≧a+b+c≧1;
• a=0-5;
• b=0-5;
• c=0-5;
• n=0 or 1;
• Y independently represents a group selected from —O—, —S—, —SO—, —SO2—, —C(O)—, arylene, alkylene, heteroarylene, heterocycloalkylene, —(G)P—, —P(O)— and —(G)N—, wherein G is selected from hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, each except hydrogen being optionally substituted by one or more functional groups E;
• R5, R6, R7, R8 independently represent a group selected from hydrogen, hydroxyl, halogen, —R and —OR, wherein R represents alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl or a carbonyl derivative group, R being optionally substituted by one or more functional groups E,
• or R5 together with R6, or R7 together with R8, or both, represent oxygen,
• or R5 together with R7 and/or independently R6 together with R8, or R5 together with R8 and/or independently R6 together with R7, represent C1-6-alkylene optionally substituted by C1-4-alkyl, —F, —Cl, —Br or —I;
• E independently represents a functional group selected from —F, —Cl, —Br, —I, —OH, —OR′, —NH2, —NHR′, —N(R′)2, —N(R′)3+, —C(O)R′, —OC(O)R′, —COOH, —COO−(Na+, K+), —COOR′, —C(O)NH2, —C(O)NHR′, —C(O)N(R′)2, heteroaryl, —R′, —SR′, —SH, —P(R′)2, —P(O)(R′)2, —P(O)(OH)2, —P(O)(OR′)2, —NO2, —SO3H, —SO3−(Na+, K+), —S(O)2R′, —NHC(O)R′, and —N(R′)C(O)R′, wherein R′ represents cyctoatkyl, aryl, arytalkyl, or alkyl optionally substituted by —F, —Cl, —Br, —I, —NH3+, —SO3H, —SO3−(Na+, K+), —COOH, —COO−(Na+, K+), —P(O)(OH)2, or —P(O)(O−(Na+, K+))2;
• T represents a non-coordinated group selected from hydrogen, hydroxyl, halogen, —R and —OR, wherein R represents alkyl, alkenyl, cyctoatkyl, heterocycloalkyl, aryl, heteroaryt or a carbonyl derivative group, R being optionally substituted by one or more functional groups E;
• U represents either a non-coordinated group T independently defined as above or a coordinating group of the general formula (II), (III) or (IV):
• wherein
• Q2 and Q4 are independently defined as for Q1 and Q3;
• Q represents —N(T)— (wherein T is independently defined as above), or an optionally substituted heterocyclic ring or an optionally substituted heteroaromatic ring selected from pyridine, pyrimidine, pyrazine, pyrazole, imidazole, benzimidazole, quinoline, quinoxaline, triazole, isoquinoline, carbazole, indole, isoindole, oxazole and thiazole;
• Z2 is independently defined as for Z1;
• Z3 groups independently represent —N(T)— (wherein T is independently defined as above);
• Z4 represents a coordinating or non-coordinating group selected from hydrogen, hydroxyl, halogen, —NH—C(NH)NH2, —R and —OR, wherein R=alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl or a carbonyl derivative group, R being optionally substituted by one or more functional groups E, or Z4 represents a group of the general formula (IIa):
• and
• 1≦j<4.