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

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 (D(2)d) and square antiprism (D(4)d) 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 mu s) is much longer than that of its precursor [Eu(btfa)(3)(H2O)] (335 +/- 0.11 mu s). 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 (Omega(2) = 33.56 x 10(-20) cm(2)) than its precursor, [Eu(btfa)(3)(H2O)(2)] (Omega(2) = 13.95 x 10(-20) cm(2)).