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Solvent reorganization energies in excited-state electron-transfer reactions. Oxidative quenching of the MLCT excited states of Ru(II)-diimine complexes

Journal Article · · Inorganic Chemistry
DOI:https://doi.org/10.1021/ic980493x· OSTI ID:321105
; ;  [1]
  1. Boston Univ., MA (United States). Dept. of Chemistry
As part of the inquiry into whether the proposed delocalization of the transferred electron among the ligands in {sup *}Ru(phen){sub 3}{sup 2+} (phen = 1,10-phenanthroline) (in contrast to the established electron localization in {sup *}Ru(bpy){sub 3}{sup 2+} in fluid solution) is of consequence to their photochemistry and photophysics, the authors reported that the quenching of both excited states by MV{sup 2+} had the same activation energy, they concluded that since {Delta}G{sub et}{sup o} is the same for both systems, {lambda} must also be the same. At issue is the generality of the effect of specific anions and the influence of electron-withdrawing and -donating ligand substituents on {lambda} and the rate of electron transfer. In this study, the authors determined the rate constants (k{sub q}) for the oxidative quenching of {sup *}Ru(phen){sub 3}{sup 2+}. {sup *}Ru(Clphen){sub 3}{sup 2+} (Clphen = 5-chloro-1,10-phenanthroline), and {sup *}Ru(Me{sub 2}phen){sub 3}{sup 2+} (Me{sub 2}phen = 5,6-diamethyl-1,10-phenanthroline) by MV{sup 2+} as a function of temperature in aqueous solution in the presence of the same concentration (0.1 M) of 1:1 supporting electrolytes (NaClO{sub 4}, NaH{sub 2}PO{sub 4}, NaF, NaCl, NaBr, NaI). The values of k{sub et} were calculated by use of the diffusional model; values of {lambda} were evaluated from the dependence of k{sub et} on T.
Sponsoring Organization:
USDOE, Washington, DC (United States)
OSTI ID:
321105
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 21 Vol. 37; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English