AZINO-FUSED BENZIMIDAZOLIUM SALTS AS DNA INTERCALATING AGENTS .2.

The synthesis of new pyrido[1,2-a]- and pyridazino[1,6-a]benzimidazoli um salts by basic condensation of 1,3-disubstituted 2-alkylbenzimidazo lium salts and 1,2-diketones and subsequent chemical transformations i s described. The DNA-binding properties were examined by UV-vis spectr oscopy, viscosimetric determinations, and molecular modeling technique s. The presence of a flat polycyclic hydrocarbon moiety such as a naph thalene-1,8-diyl or a biphenyl-o,o'-diyl, fused to the cationic hetero cycle, appears to enhance the interaction with DNA. Variation of the s ubstituents on the indole-like N will allow us to build up a new serie s of his-salts with bis-intercalating properties.