Compounds of the general formula (1) ##STR1## wherein R.sub.1 denotes hydrogen, halogen, alkyl, alkoxy or, conjointly with R.sub.2, a fused benzo ring, R.sub.2 denotes hydrogen, alkyl, alkoxy, halogen, phenyl, cyano, carboalkoxy, carboxyl, carbonamido, monoalkylcarbonamido, dialkylcarbonamido, sulfo, alkylsulfonyl, alkyloxysulfonyl, sulfonamido, monoalkylsulfonamido or dialkylsulfonamido or, conjointly with R.sub.3, a fused benzo ring, R.sub.3 has the same meaning as R.sub.2, R.sub.4 denotes hydrogen, alkyl, alkoxy, halogen or, conjointly with R.sub.3, a fused benzo ring, R.sub.5 denotes alkyl, hydroxyalkyl, alkoxyalkyl, optionally substituted aralkyl, cyanoethyl, cycloalkyl or a group of the formulae --CH.sub.2 CN, --CH.sub.2 CONH.sub.2 or --CH.sub.2 COO--alkyl, A denotes a group of the formulae ##STR2## or--(CH.sub.2).sub.4 --R.sub.6 denotes hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, aralkyl or optionally substituted phenyl, n denotes 1, 2 or 3 and X.sup.(-) denotes a halide, alkylsulfonate, alkylsulfate, alkylphenylsulfonate or phenylsulfonate ion, and processes for their preparation and their use as optical brighteners.