Azino-Fused Benzimidazolium Salts as DNA Intercalating Agents. 2.

The synthesis of new pyrido[1,2- a ]- and pyridazino[1,6- a ]benzimidazolium salts by basic condensation of 1,3-disubstituted 2-alkylbenzimidazolium salts and 1,2-diketones and subsequent chemical transformations is described. The DNA-binding properties were examined by UV-vis spectroscopy, viscosimetric determinations, and molecular modeling techniques. The presence of a flat polycyclic hydrocarbon moiety such as a naphthalene-1,8-diyl or a biphenyl- o, o '-diyl, fused to the cationic heterocycle, appears to enhance the interaction with DNA. Variation of the substituents on the indole-like N will allow us to build up a new series of bis-salts with bis-intercalating properties.