AcetylacetonateBODIPY-Biscyclometalated Iridium(III) Complexes: Effective Strategy towards Smarter Fluorescent Photosensitizer Agents

5 years ago

AcetylacetonateBODIPY-Biscyclometalated Iridium(III) Complexes: Effective Strategy towards Smarter Fluorescent Photosensitizer Agents

Rebeca Sola-Llano, Virginia Martínez-Martínez, Angeles Villanueva, Maria J. Ortiz, Iñigo López-Arbeloa, Hegoi Manzano, Eduardo Palao, Antonia R. Agarrabeitia, Andrea Tabero

Biscyclometalated IrIII complexes involving boron-dipyrromethene (BODIPY)-based ancillary ligands, where the BODIPY unit is grafted to different chelating cores (acetylacetonate for Ir-1 and Ir-2, and bipyridine for Ir-3) by the BODIPY meso position, have been synthesized and characterized. Complexes with the BODIPY moiety directly grafted to acetylacetonate (Ir-1 and Ir-2) exhibit higher absorption coefficients (ϵ≈4.46×104 m−1 cm−1 and 3.38×104 m−1 cm−1 at 517 nm and 594 nm, respectively), higher moderate fluorescence emission (φfl≈0.08 and 0.22 at 528 nm and 652 nm, respectively) and, in particular, more efficient singlet oxygen generation upon visible-light irradiation (φΔ≈0.86 and 0.59, respectively) than that exhibited by Ir-3 (φΔ≈0.51, but only under UV light). Phosphorescence emission, nanosecond time-resolved transient absorption, and DFT calculations suggest that BODIPY-localized long-lived 3IL states are populated for Ir-1 and Ir-2. In vitro photodynamic therapy (PDT) activity studied for Ir-1 and Ir-2 in HeLa cells shows that such complexes are efficiently internalized into the cells, exhibiting low dark- and high photocytoxicity, even at significantly low complex concentration, making them potentially suitable as theranostic agents. Kill and cure: New boron-dipyrromethene (BODIPY)–iridium(III) complexes, synthesized by a straightforward synthetic approach, exhibit efficient singlet oxygen generation, low dark and high photocytoxicity under visible radiation even at low photosensitizer concentrations.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701347