A new family of luminescent iridium complexes: synthesis, optical, and cytotoxic studies
Gonzalo Millán, Mattia Nieddu, Icíar P. López, Cintia Ezquerro, Jesús R. Berenguer, Ignacio M. Larráyoz, José G. Pichel, Elena Lalinde
Abstract
LL'CT (C^N → N^N) excited states with the predominant metal-to-diimine charge transfer character. Their antineoplastic activity against tumour cell lines A549 (lung carcinoma) and HeLa (cervix carcinoma), as well as the nontumor BEAS-2B (bronchial epithelium) cell line was assessed and fluorescence microscopy studies were performed for their cellular localization. Among them, 2a-Cl exhibited the most potent anticancer activity, being higher than cisplatin. However, 2b-Cl and 2c-Cl,-PF6 were the least toxic, while 2b-PF6 and 3a-PF6 exhibited only moderate activity. Confocal microscopy studies for 2a-Cl suggest that complexes localize preferentially in the lysosomes and to a lesser extent in the cytoplasm, but ultimately causing damage to the mitochondria. Finally, the potential photodynamic behaviour of scarcely toxic complexes 2b-Cl, 2b-PF6, 2c-Cl and 3a-PF6 was also studied.