It is demonstrated that even unsubstituted cationic ligands, namely the known diazoniadibenzochrysenes (, ) and the so far unreported tetraazoniapentaphenopentaphene (), stabilize quadruplex DNA upon association; the ligand exhibits essentially the same affinity towards the quadruplex as does 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine, however, with a significantly higher selectivity for quadruplex relative to duplex DNA.