Microwave-assisted synthesis and photodynamic activity of tris-heteroleptic Ru(II) complexes with asymmetric polypyridyl ligands

Ru(II) polypyridyl complexes are attracting particular attention as possible photodynamic therapy (PDT) agents due to their interesting photophysical properties, which can be easily tunable through the appropriate selection of attached ligands. However, blue-wavelength absorption of the complexes limited their potential application. In this study, three tris-heteroleptic Ru(II) polypyridyl complexes were synthesized to shift the absorption of the compounds toward longer wavelengths. Their photophysical, biological, and photodynamic properties were evaluated. The mechanism of the photoinduced toxicity was investigated by fluorescence and electron para-magnetic resonance (EPR) techniques in vitro and in aqueous solutions. The results revealed the photodynamic activity of the studied compounds is based mainly on the photogeneration of 1O2 and H2O2. Additionally, the synthesized Ru complexes demonstrated high activity in inhibiting the detachment of cancer cells. This effect was additionally enhanced by light activation of Ru compounds. The presented findings demonstrate a rational strategy for the efficient synthesis of tris-heteroleptic Ru(II) polypyridyl complexes to be used as promising photodynamic agents for cancer and antimetastatic treatments.

Automated summary

Ru(II) polypyridyl complexes are being studied as potential photodynamic therapy agents. In this study, three complexes were synthesized to shift their absorption towards longer wavelengths. The compounds showed photodynamic activity through the generation of 1O2 and H2O2, and demonstrated high activity in inhibiting cancer cell detachment.