Optical spectroscopy of the adducts of europium tris(dipivaloylmethanate) with derivatives of 1,10-phenanthroline

Spectroscopic investigations of the mutual influence of inequivalent ligand s were undertaken using complex adducts of europium tris(dipyvaloylmethanat e) with derivatives of 1,10-phenanthroline, Eu(DPM)(3). Ph. The choice of a series of related Eu(DPM)(3). Ph compounds provided the opportunity to stu dy the dependence of the spectroscopic characteristics on the value of the effective charges at the atoms in the nearest surroundings of Eu3+ which, i n turn, depends on steric factors and the donor-acceptor properties of the ligands. It was shown that steric factors are as significant as donor-accep tor properties of the ligands in the creation of the complexes. The changes in the strength and symmetry of the crystal field were evaluated from the Stark splittings of the Eu3+ transitions in luminescence spectra. Crystal h eld parameters were calculated. Two subgroups of compounds with similar spe ctra were distinguished. The relative efficiency of the excitation of Eu3luminescence through the ligand absorption bands and the relative luminance of the compounds were investigated. Changes of the ligand vibration freque ncies and the strength of the electron-phonon interaction with various liga nds were studied by IR and vibronic spectra. (C) 2000 Elsevier Science S.A. All rights reserved.