2013-05-20 02:23:40 1193 Mia Milos, Prodipta Pal, and Andreas Hauser Milos, Mia Pal, Prodipta Hauser, Andreas ChemPhysChem ChemPhysChem 1439-4235 2010 11 14 3161 3166 H [Cr(bpy)3]3+ [Cr(ox)3]3− 3D oxalate networks excitation energy transfer high pressures http://onlinelibrary.wiley.com/doi/10.1002/cphc.201000324/abstract http://onlinelibrary.wiley.com/doi/10.1002/cphc.201000324/full http://onlinelibrary.wiley.com/doi/10.1002/cphc.201000324/pdf Resonant excitation energy transfer from [Cr(ox)3]^3- to [Cr(bpy)3]³⁺ in the doped 3D oxalate networks [Rh_1-xCr_x(bpy)₃][NaM^III_1-yCr_y(ox)₃]ClO₄ (ox=C₂O₄^-, bpy=2,2’-bipyridine, M=Al,Rh) is due to two types of interaction, namely super exchange coupling and electric dipole–dipole interaction. The energy transfer probability for both mechanisms is proportional to the spectral overlap of the ²E→⁴A₂ emission of the [Cr(ox)₃]^3- donor and the ⁴A₂→²T₁ absorption of the [Cr(bpy)₃]³⁺ acceptor.The spin-flip transitions of (pseudo-)octahedral Cr³⁺ are known to shift to lower energy with increasing pressure. Because the shift rates of the two transitions in question differ, the spectral overlap between the donor emission and the acceptor absorption is a function of applied pressure. For [Rh_1-xCr_x(bpy)₃][Na-M_1-yCr_y(ox)₃]ClO₄ the spectral overlap is thus substantially reduced on increasing pressure from 0 to 2.5 GPa. As a result, the energy transfer probability decreases with increasing pressure as evidenced by a decrease in the relative emission intensity from the [Cr(bpy)₃]³⁺ acceptor.

]]> P392 10.1002/cphc.201000324 14715 http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref01193.pdf 639 Andreas Hauser, Marianne E. von Arx, Vaughan S. Langford, Sélim Kairouani, Ueli Oetliker, Anne Pillonnet Hauser, Andreas Von Arx, Marianne E. Langford, Vaughan S. Kairouani, Sélim Oetliker, Ueli Pillonnet, Anne Topics in Current Chemistry, Transition Metal and Rare Earth Compounds. Excited States, Transitions, and Interactions, Vol III Top. Cur. Chem. , Transition Metal Rare Earth Compd. Excited States, Trans. , Interactions, Vol III (ed. H. Yersin), Springer, Berlin 2004 241 H oxalate networks [Cr(ox)3]3- [Cr(bpy)3]3+ 2E state resonant energy transfer phonon-assisted energy transfer Förster transfer Exchange interaction Excitation energy transfer processes play an important role in many areas of physics, chemistry and biology. The three-dimensional oxalate networks of composition [MIII(bpy)3][MIMIII(ox)3]ClO4 (bpy=2,2-bipyridine, ox=oxalate, MI=alkali ion) allow for a variety of combinations of different transition metal ions. The combination with chromium(III) on both the tris-bipyridine as well as the tris-oxalate site constitutes a model system in which it is possible to differentiate unambiguously between energy transfer from [Cr(ox)3]3– to [Cr(bpy)3]3+ due to dipole-dipole interaction on the one hand and exchange interaction on the other hand. Furthermore it is possible to just as unambiguously differentiate between the common temperature dependent phonon-assisted energy migration within the 2E state of [Cr(ox)3]3–, and a unique resonant process.

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