A compound of the formula ##STR81## or an internal, external or acid addition salt thereof, wherein each of Q.sub.1 and Q.sub.2 is independently hydrogen or --SO.sub.3 M.sub.1,
- each R.sub.1 and R.sub.2 is independently hydrogen, C.sub.1-4 alkyl, C.sub.1-4 alkoxy or --COOM,
- R.sub.3 is hydrogen;
- cyano;
- amino;
- hydroxy;
- C.sub.1-4 -alkoxy;
- C.sub.1-4 alkyl;
- C.sub.2-4 alkyl monosubstituted by hydroxy or C.sub.1-4 alkoxy;
- C.sub.5-6 cycloalkyl;
- phenyl;
- phenyl substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 -alkoxy, halo, --COOM and --SO.sub.3 M;
- phenyl(C.sub.1-4 -alkyl);
- phenyl(C.sub.1-4 alkyl) the phenyl group of which is substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 alkoxy, halo, --COOM and --SO.sub.3 M;
- --CO--R.sub.6 ;
- --(CH.sub.2).sub.b --R.sub.7 ;
- or a saturated or unsaturated 5- or 6-membered heterocyclic ring containing 1 to 3 hetero atoms, which ring is unsubstituted or substituted by 1 to 3 C.sub.1-4 alkyl groups and is bound to Ring A by a carbon or nitrogen atom directly or via a bridge member, with the proviso that any ##STR82## is bound via a bridge member, wherein R.sub.6 is hydroxy, amino or C.sub.1-4 alkoxy,
- R.sub.7 is cyano, halo, --SO.sub.3 M, --OSO.sub.3 M, --CO--R.sub.8 or pyridyl-4, wherein
- R.sub.8 is hydroxy;
- amino;
- C.sub.1-4 alkyl;
- C.sub.1-4 alkyl monosubstituted by hydroxy, halo, cyano or C.sub.1-4 alkoxy;
- C.sub.1-4 -alkoxy;
- phenyl;
- phenyl substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 -alkoxy, halo, --COOM and --SO.sub.3 M;
- phenoxy;
- phenyl(C.sub.1-4 alkyl);
- or phenoxy or phenyl-(C.sub.1-4 alkyl) the phenyl group of which is substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 -alkoxy, halo --COOM and --SO.sub.3 M, and
- b is 1, 2 or 3,
- R.sub.4 is hydrogen;
- cyano;
- halo;
- --SO.sub.3 M;
- nitroso;
- nitro;
- --NR.sub.9 R.sub.10 ;
- C.sub.1-4 alkyl;
- C.sub.1-4 alkyl monosubstituted by hydroxy, halo, cyano, C.sub.1-4 alkoxy, phenyl, --SO.sub.3 M or --OSO.sub.3 M;
- --SO.sub.2 NH.sub.2 ;
- --CO--R.sub.11 ;
- --CH.sub.2 --NH--CO--R.sub.12 --E;
- a group of the formula ##STR83## wherein the two carbonyl or sulfonyl groups are bound to two carbon atoms of an aromatic ring that are ortho to each other;
- a group of the formula ##STR84## which is a 5- or 6-membered ring containing 1 to 3 hetero atoms which is unsubstituted or substituted by 1 or 2 methyl groups or by amino, C.sub.1-4 alkylamino or N,N-di-(C.sub.1-4 alkyl)amino;
- benzoimidazolium-1;
- benzoimidazolium-1 monosubstituted by methyl, amino, methylamino or dimethylamino;
- or a group of the formula ##STR85## wherein each of R.sub.9 and R.sub.10 is independently hydrogen;
- C.sub.1-4 alkyl;
- C.sub.1-4 alkyl monosubstituted by hydroxy, halo, cyano, C.sub.1-4 alkoxy or phenyl;
- or --CO--R.sub.12 -E,
- R.sub.11 is hydroxy;
- amino;
- C.sub.1-4 alkyl-amino;
- N,N-di-(C.sub.1-4 alkyl)amino;
- C.sub.1-4 alkyl;
- C.sub.1-4 alkoxy;
- phenyl;
- phenyl substituted by 1 to 3 substituents selected from C.sub.1-4 -alkyl, C.sub.1-4 alkoxy, halo, --COOM and --SO.sub.3 M;
- phenoxy;
- or phenoxy the phenyl group of which is substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 -alkoxy, halo, --COOM and --SO.sub.3 M,
- R.sub.13 is hydrogen, C.sub.1-4 alkyl or C.sub.1-4 -alkyl monosubstituted by hydroxy, halo, cyano, C.sub.1-4 alkoxy or phenyl,
- U.sub.1 is --S--, --NH-- or ##STR86## and V.sub.1 is a radical which, together with the ##STR87## radical, forms a 5-or 6-membered ring or a 5- or 6-membered ring fused to a 5- or 6-membered carbocyclic ring or to a 5- or 6-membered heterocyclic ring containing 1 or 2 hetero atoms, or
- R.sub.3 and R.sub.4 taken together form a 3 or 4 carbon atom chain or a 3 or 4 carbon atom chain that forms part of a further 5- or 6-membered ring by 2 vicinal chain members, and
- R.sub.5 is hydrogen;
- --NR.sub.14 R.sub.15 ;
- C.sub.1-6 alkyl;
- C.sub.2-4 -alkenyl;
- C.sub.2-4 alkynyl;
- C.sub.1-6 alkyl monosubstituted by hydroxy, cyano, C.sub.1-4 alkoxy, acetamido, --CO--R.sub.16, --SO.sub.3 M or --OSO.sub.3 M;
- C.sub.5-6 cycloalkyl;
- phenyl;
- phenyl substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 -alkoxy, halo, nitro, amino, --COOM and --SO.sub.3 M;
- phenyl(C.sub.1-4 alkyl);
- phenyl(C.sub.1-4 alkyl) the phenyl group of which is substituted by 1 to 3 substituents selected from C.sub.1-4 alkyl, C.sub.1-4 alkoxy, halo, nitro, amino, ##STR88## or a saturated or unsaturated 5- or 6-membered heterocyclic ring containing 1 or 2 hetero atoms, which ring is unsubstituted or substituted by 1 to 3 methyl groups or by amino, C.sub.1-4 alkylamino or N,N-di-(C.sub.1-4 alkyl)-amino and is bound by a carbon or nitrogen atom, wherein
- E.sub.1 is a protonatable amino group, a quaternary ammonium group, a hydrazinium group or ##STR89## wherein each R.sub.19 is independently halo, amino or an aliphatic amino group,
- each of R.sub.14 and R.sub.15 is independently hydrogen;
- C.sub.1-4 alkyl;
- C.sub.1-4 alkyl monosubstituted by hydroxy, halo, cyano or C.sub.1-4 alkoxy;
- phenyl;
- or phenyl substituted by 1 or 2 substituents selected from halo, C.sub.1-4 alkyl and C.sub.1-4 alkoxy,
- R.sub.16 is hydroxy or C.sub.1-4 alkoxy, and
- R.sub.18 is E.sub.2, --NH--CO--R.sub.12 --E.sub.2, --SO.sub.2 --NH--R.sub.12 --E.sub.2 or --CO--NH--R.sub.12 --E.sub.2, wherein
- is a protonatable amino group, a quaternary ammonium group or a hydrazinium group, and
- n is 0 or 1,
- wherein
- each E is independently hydrogen, halo, a protonatable amino group, a quaternary ammonium group, a hydrazinium group, --SO.sub.3 M or --OSO.sub.3 M,
- each R.sub.12 is independently linear or branched C.sub.1-6 -alkylene, and
- each R.sub.17 is independently hydrogen or C.sub.1-4 alkyl,
- wherein
- each M and M.sub.1 is independently hydrogen or a non-chromophoric cation, and
- each halo is independently fluoro, chloro or bromo,
- with the provisos that (i) the compound contains at least one --SO.sub.3 M or --SO.sub.3 M.sub.1 group, (ii) at least one of R.sub.4 and R.sub.5 is hydrogen, (iii) the total number of anionic groups equals or exceeds the total number of basic and cationic groups, (iv) the positive charge of each cationic group is balanced by the negative charge of an --SO.sub.3.sup..crclbar. or --COO.sup.63 group of the molecule or of an external non-chromophoric anion, and (v) the hydroxy group of any hydroxyalkyl group attached to a nitrogen atom is in other than the 1-position.