Photophysics of Ru(II)-diimine complexes in H[sub 2]O-CH[sub 3]CN mixed solvents
- Boston Univ., MA (United States)
The photophysical properties of Ru(bpy)[sub 3][sup 2+], Ru(bpz)[sub 3][sup 2+], and Ru(bpz)[sub 2](bpm)[sup 2+] (bpy = 2,2[prime]-bipyridine, bpz = 2,2[prime]-bipyrazine, bpm = 2,2[prime]-bipyrimidine) have been studied in neat and mixed CH[sub 3]CN-H[sub 2]O solutions. The temperature dependent lifetimes, room-temperature emission spectra, and quantum yields were determined for the complexes; the rate constants and activation parameters for the various photophysical pathways were calculated from the data. Shifts of the emission energy (E[sub cm]) as a function of solvent composition suggest that the excited states are preferentially solvated by water molecules. Although radiative decay is relatively insensitive to the change of solution medium, nonradiative decay (k[sub nr]) and the temperature-dependent thermal population of the metal centered d-d state, which account for more than 90% of the decay of the emitting MLCT state, are strongly dependent on solvent and temperature; the observed phenomena can be well understood on the basis that the energy level of the MLCT state, which possesses a static dipole moment, is sensitive to the polarity change of the solution medium. At lower temperatures, nonradiative decay is the dominant process, and the overall deactivation of the emitting state is faster in water-rich than in acetonitrile-rich solutions. 17 refs., 3 figs., 1 tab.
- OSTI ID:
- 5651054
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 97:46; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RUTHENIUM COMPLEXES
EMISSION SPECTRA
PHOTOLYSIS
ACETONITRILE
EXPERIMENTAL DATA
LASERS
WATER
CHEMICAL REACTIONS
COMPLEXES
DATA
DECOMPOSITION
HYDROGEN COMPOUNDS
INFORMATION
NITRILES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SPECTRA
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry
400201 - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures