Exploring weak interactions to assemble a nitrosyl–ruthenium compound able to release NO under visible light irradiation

This work reports on a novel nitrosyl–ruthenium complex bearing the azanaphthalene ligand quinazoline (qui) in its coordination sphere. The product crystallizes with an additional quinazoline molecule, yielding the compound cis-[Ru(bpy)2(qui)NO](PF6)3 · (qui). This feature leads to an absorption band at λmax = 430 nm in CH3CN and λmax = 420 nm in phosphate buffer, which promotes the photorelease of nitric oxide under visible light irradiation (λ > 400 nm), in 1 ethanol:1 water (v/v) mixture or under physiological pH. Both the intensity and energy of this transition are dependent on solvent and solution pH, suggesting that the transition has a charge transfer nature, and that the association of the second quinazoline molecule with the complex is driven by weak interactions, possibly of the π-stacking type.

Compound cis-[Ru(bpy)2(qui)NO](PF6)3 · (qui) (qui = quinazoline) was synthesized and characterized. The association with an additional qui leads to an absorption band in the visible region which is able to photoinduce the NO release. The transition energy presents reversible dependence on pH and solvent effects, suggesting that the association is driven by π-stacking.Figure optionsDownload as PowerPoint slide