Quenching of Tris (2,2´bipiridine)Chromium (III)and Tris(1,10-phenantroline)Chromium (III)excited-states by Phenols - Temperature and pH effect

PAGLIERO, DANIELA; ARGUELLO, GERARDO A; STARICCO, EDUARDO H

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

Año: 1998 vol. 115 p. 199 - 199

1010-6030

p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: normal; mso-layout-grid-align: none">The quenching rate constant kq of the excited states *Cr(bpy)33+ and *Cr(phen)33+ by several substituted phenols was investigated as a function of temperature using the time resolved luminescence quenching technique. The activation parameters showed a pH dependence. The most important contribution to the total activation entropy in basic media was found to be the electrostatic factor. The data obtained from log kq vs. DGo plot were analyzed on the basis of the current theories for electron transfer processes. The best fitting analysis in the DG#  vs. DGo plot yielded reorganization energies of 59 and 55 kcal/mol for the bipyridine and phenanthroline chromium complexes, respectively. The high v