Photophysical properties of tris(benzoyltrifluoroacetonate)Eu(III) with pyrazole complex and its precursor

Abstract

The precursor, [Eu(btfa)3(H2O)2] with yield of 84 % and its complex with monodentate pyrazole, [Eu(btfa)3(pz)2] were isolated successfully. To the best of our knowledge, no previous reports of such synthesis with a high yield of [Eu(btfa)3(H2O)2] exist in literature. Single crystal X-ray diffraction (SC-XRD) analysis demonstrates, octa-coordinate environment of Eu (III) in both the complexes. The geometry of these complexes was obtained from SHAPE v2.1 and found triangular dodecahedron (D2d) and square antiprism (D4d) for [Eu(btfa)3(H2O)2] and [Eu(btfa)3(pz)2], respectively. These complexes were further characterized by elemental, thermal analysis (TGA/DTA) and ATR-IR spectroscopy. The lifetime of [Eu(btfa)3(pz)2] (546 ± 0.35 μs) is much longer than that of its precursor [Eu(btfa)3(H2O)] (335 ± 0.11 μs). The overall quantum yield of [Eu(btfa)3(pz)2] complex (21 %) is seven times larger than its precursor (3 %). The Judd-Ofelt intensity parameters accredit that [Eu(btfa)3(pz)2] is more polarizable (Ω2 = 33.56 × 10-20 cm2) than its precursor, [Eu(btfa)3(H2O)2] (Ω2 = 13.95 × 10-20 cm2).