Vojtech Novohradsky, Anna Rovira, Cormac Hally, Alex Galindo, Gloria Vigueras, Albert Gandioso, Marie Svitelova, Roger Bresolí‐Obach, Hana Kostrhunova, Lenka Markova, Jana Kasparkova, Santi Nonell, José Ruiz, Viktor Brabec, Vicente Marchán

Although cyclometalated Ir(III) complexes have emerged as promising photosensitizers for photodynamic therapy, some key drawbacks still hamper clinical translation such as operability in the phototherapeutic window and ROS production efficiency and selectivity. In this work, we report a cyclometalated Ir(III) complex conjugated to a far-red emitting coumarin with highly favourable properties for cancer phototherapy. Ir(III)-COUPY was efficiently taken up by living HeLa cells and showed no dark cytotoxicity and impressive photocytotoxicity indexes after blue (161) and green (85) light irradiation, even under hypoxia. Importantly, a clear correlation between cell death and intracellular superoxide anion radicals' generation after visible light irradiation was demonstrated. By taking advantage of the rich photophysical properties of COUPY fluorophores and of the well-stablished anticancer activities of Ir(III) complexes, this strategy opens the door to novel fluorescent PDT agents with promising applications in theragnosis.