Imidazopyridinium cations: A new family of azonia aromatic heterocycles with applications as DNA intercalators

Abstract Two novel imidazopyridinium cations formed by a hexacyclic azonia aromatic system have been synthesized. Spectrofluorimetric titrations, circular dichroism measurements, theoretical simulations and fluorescence-based thermal denaturation experiments on these materials have shown the interesting fluorescence properties and DNA-binding ability by intercalation, with a marked preference for AT-rich sequences. Compound 2 presents the highest fluorescence quantum yield (0.32 in 5% DMSO/water and 0.46 in MeOH) and affinity for DNA (binding constant of ∼4.5 × 10 5  M −1 ). Moreover, the potential of these compounds for cell staining has been investigated in living HeLa cells by confocal microscopy imaging. This analysis showed the remarkable capacity of both compounds for uptake and accumulation by living cells.