名称:
Cationic lanthanide monoporphyrinates with Sm, Eu, Gd and Tb, synthesis and spectroscopic properties in aqueous and non-aqueous media
摘要:
The synthesis of a new series of cationic monoporphyrinates with ''light'' lanthanide ions is reported. The meso-tetrakis(4-pyridyl)porphyrin, (tpyp)H-2, was used as the tetrapyrrole ligand, and the metallation reaction with the lanthanide ions in acetyl-acetonato form, leading to Ln(tpyp)acac, where Ln = Sm, Eu, Gd and Tb, was carried out. The cationic monoporphyrinates, Ln(tmepyp)acac, were synthesized via the corresponding Ln(tpyp)acac. These complexes are freely soluble in aqueous and non-aqueous solutions, like MeOH, H2O or N,N-dimethylformamide. Their spectroscopic properties in water and DMF solutions are reported. All the complexes were characterized on the basis of their UV-vis, IR and ESR data. No ESR spectra were obtained for cationic porphyrins in DMF for Sm, Eu and Tb, while the spectra of Gd(tmepyp)acac in DMF exhibits smaller Delta H-pp (103.1 G) among the spectra of Gd-III complexes. The unexpected broad signal of Eu(t-mepyp)acac, Delta H-pp = 126.9 G, in H2O is discussed in terms of the formal oxidation state +2 for the central ion.