Photophysical Studies of Helicate and Mesocate Double-Stranded Dinuclear Ru(II) Complexes

Xu, Xinyue, Martin, Samuel J.P., Flint, Kate L., Hudson, Rohan J., Keene, F. Richard, Hall, Christopher H., and Smith, Trevor A. (2024) Photophysical Studies of Helicate and Mesocate Double-Stranded Dinuclear Ru(II) Complexes. Journal of Physical Chemistry: Part A, 128. pp. 3587-3595.

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Abstract

The metal−ligand charge transfer (3MLCT) and phosphorescence-quenching metal-centered (3MC) states of the helicate and mesocate diastereoisomers of a double-stranded dinuclear polypyridylruthenium(II) complex have been investigated using ultrafast transient absorption spectroscopy. At 294 K, transient signals of the helicate decayed significantly slower than those of the mesocate, whereas at 77 K, no clear contrast in kinetics was observed. Contributions to excited-state decay from high-lying 3MLCT states were identified at both temperatures. Spectroscopic data (294 K) suggest that the 3MC state of the helicate lies above the 3MLCT and that the reverse is true for the mesocate; this was further validated by density functional theory calculations. The stabilization of the 3MC state relative to the 3MLCT state in the mesocate was explained by a reduction in ligand field strength due to distortion near the ligand bridge, which causes further deviation from octahedral geometry compared to the helicate. This work illustrates how minor structural differences can significantly influence excited state dynamics.

Item ID: 82738
Item Type: Article (Research - C1)
ISSN: 1520-5215
Keywords: dinuclear; polypyridylruthenium; helicate; ultrafast photophysics; density functional theory
Copyright Information: © 2024 American Chemical Society.
Date Deposited: 21 May 2024 00:43
FoR Codes: 34 CHEMICAL SCIENCES > 3406 Physical chemistry > 340606 Photochemistry @ 65%
34 CHEMICAL SCIENCES > 3402 Inorganic chemistry > 340211 Transition metal chemistry @ 35%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280105 Expanding knowledge in the chemical sciences @ 100%
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