Dual action photosensitive platinum(II) anticancer prodrugs with photoreleasable azide ligands

The synthesis, characterisation and properties of novel photosensitive Pt(II) complexes [Pt(terpyridine)(N-3)]CF3SO3 (1b center dot CF3SO3) and [Pt(N<^>C<^>N)(N-3)] (2b) containing photoreleasable azide ligands with potential as dual photochemotherapeutic and photodynamic therapeutic agents are reported. Their X-ray crystal structures show distorted square-planar Pt(II) coordination geometry with pi-stacking between adjacent planar Pt units. These complexes intercalate into DNA with similar binding ability as their chlorido analogues and generate singlet oxygen upon irradiation with blue light (420 nm). Photoactivation of azido complexes leads to the release of the azide ligands and the formation of new platinum species. These properties appear to be favourable for potential dual-action photoactive prodrugs.