Synthesis and characterization of new lanthanide complexes with hexadentate hydrazonic ligands
作者:M. Carcelli、S. Ianelli、P. Pelagatti、G. Pelizzi、D. Rogolino、C. Solinas、M. Tegoni
DOI:10.1016/j.ica.2004.10.003
日期:2005.3
In this paper, we report the synthesis and the characterization of a novel series of lanthanide (III) complexes with two potentially hexadentate ligands. The ligands contain a rigid phenanthroline moiety and two flexible hydrazonic arms with different donor atom sets (NNN'N'OO and NNN'N'N"N", respectively for H2L1 (2,9-diformylphenanthroline)bis(benzoyl)hydrazone and H2L2 (2,9-diformylphenanthroline)bis(2-pyridyl)hydrazone). Both nitrate and acetate complexes of H2L1 with La, Eu, Gd, and Tb were prepared and fully characterized, and the X-ray crystal structure of the complex [Eu(HL1)(CH3COO)(2)] (.) 5H(2)O is presented. The stability constants of the equilibria Ln(3+) + H2L1 = [Ln(H2L1)](3+) and Ln(3+) + (L-1)(2-) = [Ln(Li)](+) (Ln = La(III), Eu(III), Gd(III), and Tb(III)) are determined by UV spectrophotometric titrations in DMSO at t = 25 degrees C. The nitrate complexes of H2L2 with La, Eu, Gd and Tb were also synthesized, and the X-ray crystal structures of [La(H2L2)(NO3)(2)(H2O)](NO3), [Eu(H2L2)(NO3)(2)](NO3) and [Tb(H-2 L-2)(NO3)(2)](NO3) are discussed. (c) 2004 Elsevier B.V. All rights reserved.