Sensitization of NO‐Releasing Ruthenium Complexes to Visible Light

Abstract

We report a combined spectroscopical-theoretical investigation on the photosensitization of transition metal nitrosyl complexes. For this purpose, ruthenium nitrosyl complexes based on tetradentate biscarboxamide ligands were synthesized. A crystal structure analysis of a lithium-based ligand intermediate is described. The Ru complexes have been characterized regarding their photophysical and nitric oxide (NO) releasing properties. Quantum chemical calculations have been performed to unravel the influence of the biscarboxamide ligand frame with respect to the molecular electronic properties of the NO-releasing pathway. A quantitative measure for the ligand design within photosensitized Ru complexes is introduced and evaluated spectroscopically and theoretically by using time-dependent density functional theory.

trans-Chloridotetrakis(4-methylpyridine-κN)(nitrosyl-κN)ruthenium(II) bis(hexafluoridophosphate) acetone 0.75-solvate

“…The length of the Ru-Cl bond in other complexes without nitrosyl, as trans(Cl,pyz)-[Ru(py) 4 Cl(pyz)]PF 6 and trans-(Cl,PhCN)-[Ru(py) 4 Cl(PhCN)]PF 6 are 2.415 and 2.3931 Å , respectively (Coe et al, 1995), reflecting the ability of nitrosyl as a acceptor and the ability of chlorido ligand as a good donor. The Ru1-N1 distance is 1.757 (4) Å , in agreement with the Ru-N distances found in other ruthenium(II) nitrosyl complexes (Ferlay et al, 2004), which is further supported by the stretching vibration of nitrosyl, which is 1895 cm À1 (Becker et al, 2015;Sauaia & da Silva, 2003;Togano et al, 1992).…”

Transition‐Metal Nitrosyls for Photocontrolled Nitric Oxide Delivery

“…The Ru‐NO [(mib)Ru(NO)Cl] ( 9 ) {mib: N , N′ ‐(1,2‐phenylene)bis(1‐methylimidazole‐2‐carboxamide)} exhibits higher NO release rates than [(bpb)Ru(NO)(Cl)] at a photoband of 360 nm. Following an approach similar to Mascharak's, Schiller and co‐workers employed a two‐stage strategy for preparing Ru‐NOs that display significant photosensitivity under visible light . Firstly, they employed a tetradentate biscarboxamide N 4 ligand frame to generate [(mipab)Ru(NO)Cl] ( 10 ) {mipab: N , N′ ‐(phenazine‐2,3‐diyl)‐bis(1‐methylimidazole‐2‐carboxamide)} and [(vipad)Ru(NO) Cl] ( 11 ) {vipab: N , N′ ‐(phenazine‐2,3‐diyl)bis(1‐vinylimidazole‐2‐carboxamide)} (Figure ), shifting the photoband from 380 nm to 490 nm.…”

Extended charge accumulation in ruthenium–4H-imidazole-based black absorbers: a theoretical design concept

“…In recent years ruthenium(II) polypyridyl complexes have attracted enormous attention due to their outstanding (photo)chemical and (photo)physical properties, i.e., strong stability on heat, electricity and light coupled with broad absorption bands in the visible region, and redox and catalytic activity. Thus, possible applications of such complexes range from pharmaceuticals in phototherapy agents, [1][2][3][4][5][6][7] light-emitting diodes, [8][9][10][11] molecular sensors, [12][13][14][15][16] semiconductors, 17,18 and sensitizers in dye-sensitized solar cells [19][20][21][22] (DSSCs) to supramolecular photocatalysts in the fields of water splitting and artificial photosynthesis. [23][24][25][26][27][28][29][30][31] Black absorbers based on ruthenium(II) polypyridyl complexes are widely applied in light-harvesting devices and photosensitizers due to their broad absorption bands.…”