Influence of the Protonation State on the Excited-State Dynamics of Ruthenium(II) Complexes with Imidazole π-Extended Dipyridophenazine Ligands

Müller C, Isakov D, Rau S, Dietzek B (2021)


Publication Type: Journal article

Publication year: 2021

Journal

Book Volume: 125

Pages Range: 5911-5921

Journal Issue: 27

DOI: 10.1021/acs.jpca.1c03856

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.

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APA:

Müller, C., Isakov, D., Rau, S., & Dietzek, B. (2021). Influence of the Protonation State on the Excited-State Dynamics of Ruthenium(II) Complexes with Imidazole π-Extended Dipyridophenazine Ligands. Journal of Physical Chemistry A, 125(27), 5911-5921. https://dx.doi.org/10.1021/acs.jpca.1c03856

MLA:

Müller, Carolin, et al. "Influence of the Protonation State on the Excited-State Dynamics of Ruthenium(II) Complexes with Imidazole π-Extended Dipyridophenazine Ligands." Journal of Physical Chemistry A 125.27 (2021): 5911-5921.

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