A high resolution luminescence study of two novel salts of the triethylenetetraaminehexaacetatoeuropate(III) anion

A low-temperature high-resolution luminescence study of K3Eu(TTHA). H2O and TI3Eu(TTHA). H2O has been carried out. The Eu3+ luminescence spectrum was recorded over the spectral range which includes transitions from the D-5(0) excited state to the F-7(0-4) ground state manifolds. The observed spectra l patterns are analyzed using group theoretical methods so as to deduce the site symmetry of the Eu3+ ion in the complex. The analysis shows that the Eu3+ ion occupies a spectroscopic site symmetry that approaches a D-2 symme try with distortion towards a C-2 or lower symmetry in the potassium salt a nd a site symmetry of a C-3 in the thallium salt. These salts illustrate th e potential of the counterion to markedly influence the effective site symm etry of the Eu3+ ion.