Tuning the excited-state deactivation pathways of dinuclear ruthenium(ii) 2,2′-bipyridine complexes through bridging ligand design
(2020) Dalton Transactions — Vol. 49, n° 24, p. 8096-8106 (2020)
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Cerfontaine, Simon 
- Abstract
- A detailed photophysical investigation of two dinuclear ruthenium(II) complexes is reported. The two metallic centers were coordinated to a bis-2,2′-bipyridine bridging ligand, connected either through the para (Lp, Dp) or the meta position (Lm, Dm). The results obtained herein were compared to the prototypical [Ru(bpy)3]2+ parent compound. The formation of dinuclear complexes was accompanied by the expected increase in molar absorption coefficients, i.e. 12 000 M−1 cm−1, 17 000 M−1 cm−1, and 22 000 M−1 cm−1 at the lowest energy MLCTmax transition for [Ru(bpy)3]2+, Dm and Dp respectively. The Lp bridging ligand resulted in a ruthenium(II) dinuclear complex that absorbed more visible light, and had a longer-lived and more delocalized excited-state compared to a complex with the Lm bridging ligand. Variable temperature measurements provided valuable information about activation energies to the uppermost 3MLCT state and the metal-centered (3MC) state, often accompanied by irreversible ligand-loss chemistry. At 298 K, 48% of [Ru(bpy)3]2+* excited-state underwent deactivation through the 3MC state, whereas this deactivation pathway remained practically unpopulated (<0.5%) in both dinuclear complexes.
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Cerfontaine, S., Troian-Gautier, L., Wehlin, S. A. M., Loiseau, F., Cauët, E., & Elias, B. (2020). Tuning the excited-state deactivation pathways of dinuclear ruthenium(ii) 2,2′-bipyridine complexes through bridging ligand design. Dalton Transactions, 49(24), 8096-8106. https://doi.org/10.1039/d0dt01216e (Original work published 2020)