Effect of external pressure on the excitation energy transfer from [Cr(ox)3]3- to [Cr(bpy)3]3+ in [Rh(1-x)Cr(x)(bpy)3][NaM(1-y)Cr(y)(ox)3]ClO4.
Resonant excitation energy transfer from [Cr(ox)(3)](3-) to [Cr(bpy)(3)](3+) in the doped 3D oxalate networks [Rh(1-x)Cr(x)(bpy)(3)][NaM(III) (1-y)Cr(y)(ox)(3)]ClO(4) (ox=C(2)O(4) (-), 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 (2)E→(4)A(2) emission of the [Cr(ox)(3)](3-) donor and the (4)A(2)→(2)T(1) absorption of the [Cr(bpy)(3)](3+) acceptor. The spin-flip transitions of (pseudo-)octahedral Cr(3+) 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-x)Cr(x)(bpy)(3)][NaM(1-y)Cr(y)(ox)(3)]ClO(4) 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.
Milos
Mia
M
Département de Chimie Physique, Université de Genève, 30 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Pal
Prodipta
P
Hauser
Andreas
A