Photoactive ruthenium nitrosyls derived from quinoline- and pyridine-based ligands: Accelerated photorelease of NO due to quinoline ligation

The ruthenium nitrosyl [(PaPy2Q)Ru(NO)](BF4)2, derived from the quinoline-based ligand PaPy2QH (PaPy2QH = N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-quinaldine-2-carboxamide; H = dissociable proton) has been synthesized and characterized by X-ray crystallography and spectroscopic techniques. This {Ru–NO}6 nitrosyl is soluble in aqueous media and stable under physiological conditions at pH 7. [(PaPy2Q)Ru(NO)]2+ releases NO rapidly upon exposure to low-intensity UV light (5 mW/cm2). The NO donor capacity of this nitrosyl (quantum yield = 0.20, λirr = 365 nm) is considerably higher than that of analogous nitrosyl derived from a polypyridyl ligand without the quinoline moiety.

Graphical abstractThe {Ru–NO}6 nitrosyl [(PaPy2Q)Ru(NO)](BF4)2 exhibits greater NO photolability (as detected by NO-electrode) compared to analogous nitrosyl [(PaPy3)Ru(NO)](BF4)2 due to the light-harvesting quinoline moiety in the ligand frame.Figure optionsDownload full-size imageDownload as PowerPoint slide