Crystal structure and cytotoxic activities of a bis(pyrrolyl-imine) gold(III) complex

Density functional theory (DFT) studies and cytotoxic assays were performed. Infrared, mass spectrometry, and 1 H, 13 C, and { 15 N, 1 H} nuclear magnetic resonance analyses indicate that pyren is deprotonated and gold(III) is four coordinate in a square planar environment, with the pyrrole and imine nitrogens as donors.

The structure was confirmed by powder X-ray diffraction and confirmed as a minimum of the potential energy surface by DFT. Cytotoxic activity of [Au(pyren)] + was active against three tumorigenic cell lines with IC 50 values of 35 μM. Interaction studies with CT-DNA by fluorescence and competition with ethidium bromide (EB) showed a quenching of the emission band of DNA with a Stern–Volmer quenching constant value of (3.0 ± 0.1) × 10 4 M −1 and a decrease in fluorescence quenching of EB-DNA system, respectively, confirming that DNA is a possible target for the complex via an intercalative binding, which was confirmed by DNA conformational changes observed with circular dichroism spectroscopy.