Temperature dependence of the Ru(bpy)/sub 2/(CN)/sub 2/ and Ru(bpy)/sub 2/(i-biq)/sup 2 +/ luminescence

Journal Article · Wed Feb 25 23:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100289a018· OSTI ID:6770952

Barigelletti, F; Juris, A; Balzani, V; Belser, P; von Zelewsky, A

The luminescence behavior (emission spectrum and lifetime) of the uncharged cis-Ru(bpy)/sub 2/(CN)/sub 2/ complex (bpy = 2,2'-bipyridine) has been studied in propionitrile-butyronitrile solution in the temperature range 84-310 K and compared with that of the Ru(bpy)/sub 2/(i-biq)/sup 2 +/ cation (i-biq = 2,2'-isobiquinoline). For both complexes luminescence originates from triplet Ru ..-->.. bpy metal-to-ligand charge-transfer (/sup 3/MLCT) excited states, with CN/sup -/ and i-biq playing the role of spectator ligands. The red shift of the emission maximum observed in the temperature range 110-160 K is attributed to relaxation processes related to changes in the solvent matrix viscosity. The changes in emission lifetime with increasing temperature are accounted for by Arrhenius paths, which lead to the population of upper excited states, and solvent matrix effects, which involve either relaxation of metal-ligand vibrational coordinates or rearrangement of the solvation shell. The contributions of these processes to the overall rate constant of radiationless decay have been estimated from an analysis of the ln 1/tau vs 1/T plots. The solvent rearrangement effect is much more important for Ru(bpy)/sub 2/(CN)/sub 2/ than for Ru(bpy)/sub 2/(i-biq)/sup 2 +/. The values of the kinetic parameters of the Arrhenius path that becomes important at high temperature suggest that Ru(bpy)/sub 2/(CN)/sub 2/ and Ru(bpy)/sub 2/(i-biq)/sup 2 +/ exemplify two different limiting cases of radiationless decay behavior.

• Research Organization: Univ. of Bologna, Italy
• OSTI ID: 6770952
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:5; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AZINES
BIPYRIDINES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
EMISSION SPECTROSCOPY
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
LUMINESCENCE
NITRILES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PYRIDINES
REACTION KINETICS
RUTHENIUM COMPLEXES
SOLVENT PROPERTIES
SOLVENTS
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPLEXES