Photoexcited states of biruthenium(II) compounds bridged by 2,2 prime -bis(2-pyridyl)bibenzimidazole or 1,2-bis(2-(2-pyridyl)benzimidazolyl)ethane
- Osaka Univ. (Japan)
- Mie Univ. (Japan)
Charge-transfer (CT) excited states of RuL{sub 2}(L{prime}-L{prime}){sup 2+} and RuL{sub 2}(L{prime}-L{prime}){sup 4+} have been studied by means of emission and transient absorption (TA) spectroscopy at 77-300 K. The bridging ligand (L{prime}-L{prime}) is either 2,2{prime}-bis(2-pyridyl)benzimidazole (bpbimH{sub 2}) or 1,2-bis(2-(2-pyridyl)benzimidazolyl)ethane (dpbime) and L is 2,2{prime}-bipyridine (bpy), 4,4{prime}-dimethyl-2,2{prime}-bipyridine (dmbpy), or 1,10-phenanthroline (phen). Transient absorption (TA) spectra of the ruthenium(II) compounds subjected to laser excitation, whose molar extinction coefficients were determined, are deconvoluted to {pi}-{pi}* bands of L and L{prime}-L{prime} coordinating to Ru(III), L (or L{prime}-L{prime})-to-Ru(III) CT bands, and a {pi}-{pi}* band of (L{prime}-L{prime}){sup {center dot}-} (or L{sup {center dot}-}) by comparison with the absorption spectra of the oxidized compounds (RuL{sub 2}(L{prime}-L{prime}){sup 3+}). The degree of electron population on the ligand decreases in the order bpbimH{sub 2} > bpy {approximately} phen > dpbime > dmbpy in the excited CT states, while there is no discernible difference in the reduction potential between bpbimH{sub 2} (or dpbime) and bpy coordinating to Ru(II). The excitation efficiency of the metal sites in (Ru(bpy){sub 2}){sub 2}(dpbime){sup 4+} is lower than 50% when the laser power was large enough to excite more than 80% of the mononuclear compounds. The low excitation efficiency of the former is ascribed to rapid intramolecular annihilation of the excited states.
- OSTI ID:
- 6957439
- Journal Information:
- Inorganic Chemistry; (United States), Vol. 31:4; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RUTHENIUM COMPLEXES
PHOTOCHEMISTRY
ABSORPTION SPECTRA
CHARGE TRANSPORT
CHEMICAL PREPARATION
ELECTRIC POTENTIAL
EMISSION SPECTRA
EXCITED STATES
LASER RADIATION
LIGANDS
LUMINESCENCE
MOLECULAR STRUCTURE
OXIDATION
PHOSPHORESCENCE
PHYSICAL PROPERTIES
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
VOLTAMETRY
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
RADIATIONS
SPECTRA
SYNTHESIS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry