Room-temperature fluorescence, phosphorescence and crystal structure of 4-acyl pyrazolone lanthanide complexes: Ln(L)(3)center dot 2H(2)O

A series of ternary mixed ligand 4-acyl pyrazolone lanthanide complexes: Ln(L)(3) . 2H(2)O [where Ln = Tb3+ or Gd3+, L = 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (PMAP), 1-phenyl-3-methyl-4-propionyl-5-pyrazolone (PMPP), 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone (PMIP), 1-phenyl-3-methyl-4-neovaleryl-pyrazolone-5 (PMNP) and 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMHP)] were synthesized and characterized by FT-IR spectra, UV-vis spectra and DTA-TG analysis. Room-temperature phosphorescence was observed from the Gd3+ complexes by excitation of the sample with the fourth harmonic frequency of a Nd:YAG laser beam (lambda = 266 nm) and the tripler energies of the pyrazolone ligands were evaluated. Both the fluorescence intensity and fluorescence lifetime of the Tb3+ complexes depend on the structure of the ligands and explanations are presented. The crystal structure [Tb(PMPP)(3) . 2H(2)O]. EtOH was determined by X-ray diffraction. The structure was refined to R = 0.064 (R(w) = 0.073). The complex is mononuclear and the central terbium ion is coordinated by eight oxygen atoms to form a square-antiprism coordination polyhedron, six of which are from the three bidentate pyrazolone ligands and the other two are from the two coordination water molecules. Copyright (C) 1997 Elsevier Science Ltd.