Compounds of the formula (I) ##STR1## in which R is hydrogen, or lower alkyl, which may be substituted by phenyl, hydroxy, lower carbalkoxy or cyano, X is hydrogen, chlorine, methyl, methoxy, cyano or lower carbalkoxy, n is 1 to 3, and A is an aromatic carboxylic group or an aromatic hetero-cyclic 5- or 6-membered group as well as their N-alkylated quaternary reaction products. These compounds are useful as optical brighteners for lacquers, natural or synthetic fibers and films, foils or other shaped forms made therefrom.