Luminescent Cyclometalated Platinum(II) Complex Forms Emissive Intercalating Adducts with Double-Stranded DNA and RNA: Differential Emissions and Anticancer Activities

Luminescent metallo-intercalators are potent biosensors of nucleic acid structure and anticancer agents targeting DNAs. There are few examples of luminescent metallointercalators which can simultaneously act as emission probes of nucleic acid structure and display promising anticancer activities. Herein, we describe a luminescent platinum(II) complex, [Pt(C<^>N<^>N)(C NtBu)]ClO4 (1a, HC boolean AND N boolean AND N = 6-phenyl-2,2'-bipyridyl), that intercalates between the nucleobases of nucleic acids, accompanied by an increase in emission intensity and/or a significant change in the maximum emission wavelength. The changes in emission properties measured with double-stranded RNA (dsRNA) are different from those with dsDNA used in the binding reactions. Complex 1a exhibited potent anticancer activity towards cancer cells in vitro and inhibited tumor growth in a mouse model. The stabilization of the topoisomerase I-DNA complex with resulting DNA damage by 1a is suggested to contribute to its anticancer activity.