Pentacyclic derivatives having the general formulae (Ia), (Ib) and (Ic) ##STR1## denote: hydrogen, alkyl with 1 to 20 carbon atoms polyoxyhydrocarbyl, phenyl, phenylalkyl with 1 to 3 carbon atoms in the alkyl chain, wherein the alkyl residues or/and phenyl residues can be substituted by one or several hydroxy, halogen, sulfo, carboxy or alkoxycarbonyl groups in which alkoxy can have 1 to 4 carbon atoms; R.sup.7 denotes an alkyl group with 1 to 7 carbon atoms, substituted by at least one halogen, or denotes a carboxyalkyl group or a phenyl group which is substituted by a carboxy or alkoxycarbonyl group located at the o-position relative to the carbon atom bound to the pentacyclic ring system and by at least one halogen, wherein alkoxy can have 1 to 4 carbon atoms, or a carboxymethylene-oxy-alkyloxy group; the residues R.sup.14 and R.sup.15 as well as the positions on the rings in the formulae that are not marked by specific symbols denote any desired substituents which may optionally be linked together; the two bonds marked by a broken line mean that the two carbon atoms which are joined by the bond marked by a broken line can be linked together by a single or double bond; and X.sup.- is a counterion; as well as their derivatives activated at least at one of the residues R.sup.1, R.sup.7 or/and R.sup.13. The compounds can be used as absorption or fluorescent dyes, in particular as markers for hapten/antibody/protein conjugates, as laser dyes and as an absorption medium for solar collectors.