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Influence of the Protonation State on the Excited-State Dynamics of Ruthenium(II) Complexes with Imidazole π-Extended Dipyridophenazine Ligands
- Source :
- The Journal of Physical Chemistry A. 125:5911-5921
- Publication Year :
- 2021
- Publisher :
- American Chemical Society (ACS), 2021.
-
Abstract
- Ruthenium(II) complexes, like [(tbbpy)2Ru(dppz)]2+ (Ru-dppz; tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine, dppz = dipyrido-[3,2-a:2',3'-c]phenazine), have emerged as suitable photosensitizers in photoredox catalysis. Since then, there has been ongoing interest in the design of π-extended Ru-dppz systems with red-shifted visible absorption maxima and sufficiently long-lived excited states independent of the solvent or pH value. Herein, we explore the photophysical properties of protonation isomers of the linearly π-extended [(tbbpy)2Ru(L)]2+-type complexes bearing a dppz ligand with directly fused imidazole (im) and methyl-imidazole units (mim) as L. Steady-state UV-vis absorption, resonance Raman, as well as time-resolved emission and transient absorption spectroscopy reveal that Ru-im and Ru-mim show desirable properties for the application in photocatalytic processes, i.e., strong visible absorbance and two long-lived excited states in the 3ILCT and 3MLCT manifold, at pH values between 3 and 12. However, protonation of the (methyl-)imidazole unit at pH ≤ 2 unit causes decreased excited-state lifetimes and an emission switch-off.
- Subjects :
- 010304 chemical physics
Absorption spectroscopy
chemistry.chemical_element
Photoredox catalysis
Protonation
010402 general chemistry
Resonance (chemistry)
Photochemistry
01 natural sciences
0104 chemical sciences
Ruthenium
chemistry.chemical_compound
Bipyridine
chemistry
Excited state
0103 physical sciences
Imidazole
Physical and Theoretical Chemistry
Subjects
Details
- ISSN :
- 15205215 and 10895639
- Volume :
- 125
- Database :
- OpenAIRE
- Journal :
- The Journal of Physical Chemistry A
- Accession number :
- edsair.doi.dedup.....5bf5ecb1a388e54ef94f20f5bab6f0d4