Red/NIR G-Quadruplex Sensing, Harvesting Blue Light by a Coumarin-Naphthalene Diimide Dyad.

A conceptually new light-up nucleic acid fluorescent probe resulting from the conjugation of a coumarin to a naphthalene diimide exhibits a single wavelength emission at 498 nm when free in solution and an additional red/NIR emission when bound to G-quadruplex DNA. The light-up response centred at 666 nm is highly specific for quadruplex DNA when compared to duplex DNA or to RNA quadruplexes.