Lanthanide-mediated supramolecular cages and host-guest interactions.

The structure and thermodynamic properties of lanthanide complexes with a new tripodal ligand L2 have been elucidated using different physicochemical methods. At stoichiometric ratios, the tetrahedral three-dimensional complexes with lanthanide cations are formed in acetonitrile with good stabilities. Despite minor structural changes comparing to previously investigated tripodal ligands, the resulting assembly exhibits different features revealed with the crystal structure of [Eu(4)L2(4)](OH)(ClO(4))(11) (orthorhombic, Pbcn).

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.

Structural study of mixed crystals of [Zn(1-x)Ru(x)(bpy)(3)][NaCr(ox)(3)] probed by high-resolution absorption spectroscopy and high-pressure experiments.

In the mixed crystal series of the cubic three-dimensional networks of composition [Zn(1-x)Ru(x)(bpy)(3)][NaCr(ox)(3)] (0 (2)E transition (R-lines) reveals the creation of five specific spectroscopic sites for the [Cr(ox)(3)](3-) complex. The concentration of these spectroscopic sites follows a binomial distribution of [Zn(bpy)(3)](2+) and [Ru(bpy)(3)](2+) among the four nearest neighbors of a given [Cr(ox)(3)](3-) complex within the network. The tris-bipyridine complexes occupying those positions have an optimal pi-pi interaction with the oxalate ligands of the tris-oxalate chromophore.