Water‐Soluble Rhenium Clusters with Triazoles: The Effect of Chemical Structure on Cellular Internalization and the DNA Binding of the Complexes

Here we explore the effect of the nature of organic ligands in rhenium cluster complexes [Re6Q8L6]4− (where Q=S or Se, and L=benzotriazole, 1,2,3‐triazole or 1,2,4‐triazole) on the biological properties of the complexes, in particular on the cellular toxicity, cellular internalization and localization. Specifically, the study describes the synthesis and detailed characterization of the structure, luminescence and electrochemical properties of the four new Re6 clusters with 1,2,3‐ and 1,2,4‐triazoles. Biological assays of these complexes are also discussed in addition to those with benzotriazole using cervical cancer (HeLa) and immortalized human fibroblasts (CRL‐4025) as model cell lines. Our study demonstrates that the presence of hydrophobic and π‐bonding rich units such as the benzene ring in benzotriazole significantly enhances cellular internalization of rhenium clusters. These ligands facilitate binding of the clusters to DNA, which results in increased cytotoxicity of the complexes. Way to go: The structure of terminal triazole ligands alter the biological properties of rhenium cluster complexes, in particular their cellular internalization and toxicity profiles. Specifically, unlike clusters with 1,2,3‐ or 1,2,4‐triazole those with benzotriazole ligands demonstrated specific cellular internalization and binding to DNA due to the π‐rich benzene unit.