ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The temperature dependence of the emission lifetime of the series of complexes Ru(bpy)n(4,4′-dpb)2+3- (bpy = 2,2′bipyridine, 4,4′-dpb = 4,4′-diphenyl-2,2′-bipyridine) has been studied in propionitrile/butyronitrile (4:5 v/v) solutions in the range 90-293 K. The obtained photophysical parameters show that the energy separation between the metal-to-ligand charge tranfer (3MLCT) emitting level and the photoreactive metal-centered (3MC) level changes across the series (ΔE = 3960, 4100, 4300, and 4700 cm-1 for Ru(bpy)2+3), Ru(bpy)2(4,4′-dpb)2+, Ru(bpy)(4,4′-dpb)2+2, and Ru(4,4′-dpb)2+3, respectively, where ΔE is the energy separation between the minimum of the 3MLCT potential curve and 3MLCT - 3MC crossing point. Comparison between spectral and electrochemical data indicated that the changes in ΔE are due to stabilization of the MLCT levels in complexes containing 4,4′-dpb with respect to Ru(bpy)2+3. The photochemical data for the same complexes (as I- salts) have been obtained in CH2Cl2 in the presence of 0.01M Cl- upon irradiation at 462 nm. The complexes containing 4,4′-dpb are more photostable than Ru(bpy)2+3. Comparison between the data for thermal population of the 3MC photoreactive state and those for photochemistry indicated that the overall photochemical process is governed by (i) a thermal redistribution between the emitting and photoreactive excited states, and (ii) mechanistic factors, likely related to the size of the detaching ligand.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19880710407
