Synthesis, Crystal Structure and Optical Properties of Europium Trifluoroacetate Complexes with 1,10‐Phenanthroline and 2,2′‐Bipyridine

Abstract

AbstractTwo europium trifluoroacetate complexes, Eu(CF3COO)3·phen (1) and Eu(CF3COO)3·bpy (2) (where phen=1,10‐phenanthroline, bpy=2,2′‐bipyridine), were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), photoluminescence (PL) spectroscopy and thermogravimetric analysis (TA). Single‐crystal X‐ray structure has been determined for the complex [Eu2(CF3COO)6·(phen)3·(H2O)2]·EtOH. The crystal structure of [Eu2(CF3COO)6·(phen)3·(H2O)2]·EtOH shows that two different coordination styles with europium ions coexist in the same crystal and have entirely different coordination geometries and numbers. This crystal can be considered as an 1:1 adduct of [Eu(CF3COO)3·(Phen)2·H2O]·EtOH (9‐coordination part) and Eu(CF3COO)3·phen·H2O (8‐coordination part). The excitation spectra of the two complexes demonstrate that the energy collected by "antenna ligands" is transferred to Eu3+ ions efficiently. The room‐temperature PL spectra of the complexes are composed of the typical Eu3+ ions red emission, due to transitions between 5D0→7FJ(J=0→4). The lifetimes of 5D0 of Eu3+ in the complexes were examined using time‐resolved spectroscopic analysis, and the lifetime values of Eu(CF3COO)3·phen and Eu(CF3COO)3·bpy were fitting with bi‐exponential (2987 and 353 µs) and monoexponential (3191 µs) curves, respectively. In order to elucidate the energy transfer process of the europium complexes, the energy levels of the relevant electronic states had been estimated. The thermal analyses indicate that they are all quite stable to heat.