Cyclometalated Iridium(III) Imidazole Phenanthroline Complexes as Luminescent and Electrochemiluminescent G‑Quadruplex DNA Binders

Six
cyclometalated iridium­(III) phenanthroimidazole complexes with different
modifications to the imidazole phenanthroline ligand exhibit enhanced
luminescence when bound to guanine (G-) quadruplex DNA sequences.
The complexes bind with low micromolar affinity to human telomeric
and c-myc sequences in a 1:1 complex:quadruplex stoichiometry. Due
to the luminescence enhancement upon binding to G-quadruplex DNA,
the complexes can be used as selective quadruplex indicators. In addition,
the electrogenerated chemiluminescence of all complexes increases
in the presence of specific G-quadruplex sequences, demonstrating
potential for the development of an ECL-based G-quadruplex assay.