Photoluminescent DNA binding and cytotoxic activity of a platinum(II) complex bearing a tetradentate β-diketiminate ligand

A platinum(II) complex of a monoanionic, tetradentate beta-diketiminate (BDI) ligand with pendant quinoline arms, (BDIH)-H-QQ, is reported. The complex, [Pt(BDIQQ)]Cl, is emissive in DMSO, but non-emissive in aqueous buffer. Upon binding DNA in buffer, however, a 150-fold turn-on in emission intensity occurs. Dynamic light scattering and H-1 NMR spectroscopy indicate that [Pt(BDIQQ)]Cl forms non-emissive aggregates in aqueous solution; DNA-binding disperses the aggregates leading to the large emission turn-on response. The cytotoxic activity of the complex, measured in two cancer cell lines, is comparable to or better than that of the established anticancer drug cisplatin.