Molecular engineering of metal-based photosensitizers with narrow band gap for efficient photodynamic therapy.

Three iridium(III) complexes were designed with the purpose of elucidating the photo-physicochemical properties of iridium(III) complexes with narrow band gap at the electronic level. This study indicates that increasing the ligand rigidity and electron delocalization of the compounds can suppress the ring-stretching vibrations of the iridium(III) complex, thus improving their photo-chemical activity and photocytotoxicity.