Structure, photophysics and magnetism of a europium mixed complex, Eu(HFAA)3bipy.H2O, in the solid state and solution

Lanthanide beta-diketones were used recently in organic-layered electroluminescence diodes and can also find other optical applications. An important characteristic of these materials can be correlated with donor-acceptor properties of the substituents in ligands. Single crystals of C35H21EuF18N4O7 were obtained. The X-ray diffraction analysis shows the triclinic system and space group P (1) over bar. The europium ion is coordinated by six oxygen atoms of hexafluoroacetylacetone and two nitrogen atoms of the 2,2'-dipyridine molecule. The coordination number of Eu(III) is completed to nine by one water molecule. Besides, one non-coordinated 2,2'-dipyridine is located in the crystal lattice which is disordered over two positions. Absorption, emission and emission excitation spectra at 293, 77 and 4 K, as well as luminescence decay time measurements are used to characterize the title compound in the solid state and in solution. The emission properties are strongly dependent on the energy of the excitation beam and on temperature. Magnetic susceptibility measurements were carried out down to 1.7 K. Correlation of the spectra and magnetic properties with details of the structure of C35H21EuF18N4O7 was studied. These results are compared with previously reported data for related systems. (C) 2002 Elsevier Science B.V. All rights reserved.