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Title

Superexchange and Dipole-Dipole Energy Transfer from the [Cr(ox)3]3- of 3D Oxalate Networks to Encapsulated [Cr(bpy)3]3+

Authors
Langford, Vaughan Stephen
Von Arx, Marianne Elisabeth
Published in Journal of Physical Chemistry. A. 1999, vol. 103, no. 36, p. 7161-7169
Abstract Electronic energy transfer from [Cr(ox)3]3- (ox = oxalate) in three-dimensional (3D) anionic oxalate networks to encapsulated [Cr(bpy)3]3+ (bpy = 2,2‘-bipyridine) cations at 1.5 K was investigated by time-resolved luminescence spectroscopy. Two series of mixed crystals of nominal compositions [NaAl1-xCrx(ox)3][Rh0.99Cr0.01(bpy)3]ClO4 (x = 0, 0.01, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, and 1) and [NaAl0.99Cr0.01(ox)3][Rh1-yCry(bpy)3]ClO4 (y = 0, 0.01, 0.02, 0.03, 0.04, and 0.05) were utilized. Energy transfer from [Cr(ox)3]3- to [Cr(bpy)3]3+ occurs by two mechanisms. Rapid, short-range transfer (ket > 106 s-1) is attributed to superexchange coupling between the Cr3+ ions via π overlap of the oxalate and bipyridine ligands. In addition, at low [Cr(ox)3]3- concentrations (nominally x = 0.01) a very much slower process with a maximum ket ≈ 200 s-1 is identified in the time-resolved spectra and attributed to a dipole−dipole mechanism. Furthermore, the resonant [Cr(ox)3]3- to [Cr(ox)3]3- energy migration previously reported by von Arx et al. (Phys. Rev. (1996), B54, 15800) assists [Cr(ox)3]3- to [Cr(bpy)3]3+ transfer as the [Cr(ox)3]3- concentration increases.
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Research group Groupe Hauser
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LANGFORD, Vaughan Stephen, VON ARX, Marianne Elisabeth, HAUSER, Andreas. Superexchange and Dipole-Dipole Energy Transfer from the [Cr(ox)3]3- of 3D Oxalate Networks to Encapsulated [Cr(bpy)3]3+. In: Journal of Physical Chemistry. A, 1999, vol. 103, n° 36, p. 7161-7169. https://archive-ouverte.unige.ch/unige:2739

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Deposited on : 2009-09-21

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