Human telomeric G-quadruplex DNA enabled preferential recognition of copper (II) and Iron (III) ions sensed by a red emissive probe

[Display omitted] Metal ions regulate several cellular processes in humans and other life forms and their balance in the body is essential for a healthy life. Specific detection of metal ions is important from both physiological and environmental perspectives. We report here the discovery of human telomeric G-quadruplex DNA enabled selective recognition of Cu2+ and Fe3+ ions using a molecular rotor that displays emission in the red region of the spectrum. This probe selectively senses Cu2+ and Fe3+ ions among a pool of other metal cations (monovalent, divalent, trivalent) and its sensing efficiency is maintained even at nanomolar levels of the DNA-probe complex. Circular dichroism and UV–visible spectroscopy-based studies revealed that the metal recognition abilities are linked to selective interaction of compound 1 with the human telomeric G-quadruplex DNA and its subsequent displacement upon binding of certain metal ions. The probe also shows robust sensing performance in the presence of other metal ions. Between Cu2+ and Fe3+, the recognition of Cu2+ is more sensitive with 3 ppb limit of detection.