Nitric oxide (NO) photo-release in a series of ruthenium–nitrosyl complexes: new experimental insights in the search for a comprehensive mechanism

Max Roose (1) , Marine Tassé (1) , Pascal G. Lacroix (1) , Isabelle Malfant (1)

1 LCC - Laboratoire de chimie de coordination

A series of four ruthenium(ii) complexes built from the [Ru(terpy)(bipy)(NO)](3+) core (terpy is 2,2:6,2-terpyridine and bipy is 2,2-bipyridine) are investigated. They differ by the presence of zero, one, two, or three 4-(4-methoxyphenyl) (MP) electron donor substituents introduced at different positions on the pyridine fragments to increase the intramolecular charge transfer capabilities towards the strongly withdrawing nitrosyl (NO) ligand. The UV-visible spectra reflect the presence and position of the MP substituents on the complexes. In the case of species containing the 4-(MP)-terpy ligand, a low-lying transition is identified as arising from 4-(MP)-terpy to Ru(NO) intramolecular charge transfer, which is further confirmed by TD-DFT analysis. Irradiation performed at = 436 nm on this isolated transition for different complexes leads to quantum yields of NO photo-release equal to 0.002 and 0.011, in a ratio of 6 (instead of 1), which allows concluding non-ambiguously that a single electron transition cannot account for the NO release mechanism.

Domaines: Chimie de coordination

Max Roose, Marine Tassé, Pascal G. Lacroix, Isabelle Malfant. Nitric oxide (NO) photo-release in a series of ruthenium–nitrosyl complexes: new experimental insights in the search for a comprehensive mechanism. New Journal of Chemistry, 2019, 43 (2), pp.755-767. ⟨10.1039/c8nj03907k⟩. ⟨hal-02140608⟩