G-quadruplex fluorescence sensing by core-extended naphthalene diimides

Background: Fluorescent sensing of G-quadruplex nucleic acids (G4s) is an effective strategy to elucidate their role in vitro and in vivo. Small molecule ligands have often been exploited, producing an emission light up upon binding. Naphthalene diimides (NDIs), although potent G4 binders exhibiting red-NIR fluorophores, have only been marginally exploited, as they are usually quenched upon binding. Contrary, aggregating core-extended naphthalene diimides (c(ex)-NDIs) proved to be effective probes.