Optical Intramolecular Electron Transfer in Opposite Directions through the Same Bridge That Follows Different Pathways
(2018) Journal of the American chemical society — Vol. 140, n° 23, p. 7176-7186 (2018)
Files
Manuscript_No_Track_Changes_Final.pdf
Open Access - Adobe PDF
- 2.18 MB
Details
- Authors
Sampaio, Renato N. 
Meyer, Gerald J.
- Abstract
- The electrochemical and spectroscopic properties of eight bis(tridentate) cyclometalated RuII compounds covalently linked by a phenyl- or xylyl-thiophene bridge to a pendant triphenylamine (TPA) were characterized in fluid solution and immobilized on metal oxide surfaces. Upon surface immobilization, the TPA+/0 reduction potentials of the phenyl-bridged compounds exhibited large changes, ±100 mV, relative to solution-based values, yet those observed for the xylyl-bridged compounds were relatively unchanged. The highest occupied molecular orbital of the surface-immobilized compounds was associated with either TPA or RuII, enabling the study of the electron transfer in opposite directions. Electron transfer in the mixed-valent states of the compounds was found to proceed by different optical pathways for RuII → TPA+ relative to TPA → RuIII. Mulliken–Hush analysis of intervalence charge transfer bands for the phenyl-bridged compounds revealed that the electronic coupling matrix element, HDA, was ∼950 cm–1 for RuII → TPA+, while HDA for TPA → RuIII appeared to be 2500 cm–1. In contrast, the xylyl-bridged compounds were weakly coupled. A superexchange analysis, where unoccupied bridge orbitals were taken directly into account, led to a very different conclusion: HDA did not depend on the charge-transfer direction or path. The results imply that the electron-transfer direction can alter optical charge transfer pathways without influencing the electronic coupling.
- Affiliations
Citations
Piechota, E. J., Troian-Gautier, L., Sampaio, R. N., Brennaman, M. K., Hu, K., Berlinguette, C. P., & Meyer, G. J. (2018). Optical Intramolecular Electron Transfer in Opposite Directions through the Same Bridge That Follows Different Pathways. Journal of the American chemical society, 140(23), 7176-7186. https://doi.org/10.1021/jacs.8b02715 (Original work published 2018)