Photophysics of Ru(II)-diimine complexes in H[sub 2]O-CH[sub 3]CN mixed solvents

Journal Article · Thu Nov 18 04:00:00 EST 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100148a018· OSTI ID:5651054

Sun, H; Hoffman, M Z ^[1]

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1. 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), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:46; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201 -- Chemical & Physicochemical Properties
400500* -- Photochemistry
ACETONITRILE
CHEMICAL REACTIONS
COMPLEXES
DATA
DECOMPOSITION
EMISSION SPECTRA
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
INFORMATION
LASERS
NITRILES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RUTHENIUM COMPLEXES
SPECTRA
TRANSITION ELEMENT COMPLEXES
WATER