Despite the good activity exhibited by the azides, we were intrigued by the anomalous behavior of the DpC azides in SK-BR-3 cells. As mentioned in the introduction, DpTs exert anticancer activity through multiple pathways involving iron and copper cation chelation. We hypothesized that the presence of the azide linker and the mixture of E/Z isomers might affect the chelating ability of the molecules. Hence, we decided to compare the binding constants of the azides with Fe(II) and Cu(II) ions to those of the parent DpTs.