Next, the phototoxicity effect of the chelates in CT26 cell line was assessed by using a broadband lamp (LED) with a light dose (L.D.) of 2.6 J.cm -2 . Accurate light doses were estimated considering the overlap between the LED and the photosensitizer spectrum. Final concentration of 13a-16 was in the range from 0.62 to 20 μM, whereas concentrations from 0.31 to 10 μM of 17 were used (Error! Reference source not found.). Our results showed that complexes 13a, 13f and 13i (Error! Reference source not found.A, D and F) are not phototoxic at the indicated light dose, while 13c (8B) showed a marginal phototoxicity at 20 μM. Complex 13d displayed a higher phototoxic effect, since it reduced cell viability by 50-60 % at 20 μM (Error! Reference source not found.C).