Structure-Property Relationships in Novel {RuNO}6 Complexes for Photoinduced NO Release

The present work describes the synthesis and characterization of a series of ruthenium nitrosyl {RuNO}⁶ complexes bearing tetradentate salophen ligands functionalized with electron-donating and electron-withdrawing substituents. The study aimed to evaluate how ligand electronic properties influence the spectroscopic features and photoinduced nitric oxide (NO) release. The complexes were characterized by UV-Vis, FT-IR, and NMR spectroscopy, complemented by DFT and TD-DFT calculations. All compounds exhibited absorption bands in the visible region, allowing photoactivation with blue and green light (470 and 525 nm). Solution studies demonstrated good stability under dark conditions and spectroscopic changes upon irradiation consistent with NO photorelease. These findings provide valuable insights into the structure-property relationships governing ruthenium nitrosyl complexes and contribute to the rational design of photoactivatable NO donors with potential biomedical applications.