Acylpyrazolonate-based lanthanide complexes: Synthesis, crystal structures and photoluminescence properties

Two new acylpyrazolonate-based lanthanide complexes of formula [Ln(pmap)(3)(H2O)2]center dot CH3COOC2H5 (Ln = Tb 1, Eu 2 and pmap = 1-phenyl-3-methyl-4-acetyl-5-pyrazolonate) have been prepared and characterized by X-ray single crystal determination and spectroscopic methods. The crystal structure analysis reveals that 1 and 2 are isostructural and crystallize in the triclinic space group P (1) over bar with two independent, but structurally similar molecules in the structural unit, which are exceptionally rare in acylpyrazolonate-based mononuclear lanthanide complexes. In CH3CN solution, the photoluminescence investigation demonstrates that 1 displays intensely green emission of Tb(III)-centered, while Eu(III)-complex does not emit characteristically red luminescence. The results are elucidated in terms of the energy gap Delta E((3)pi pi*-D-5(4) or D-5(0)) between Hpmap ligand and resonance levels of Tb(III) or Eu(III) ion. (C) 2011 Elsevier B.V. All rights reserved.