Complexation studies of Eu(III) by a novel soft N and hard O donor combined ligand including N,N,N',N'-Tetrakis(2-pyridylmethyl)-1,3-diaminopropane-2-amide structure. UV-vis titration, X-ray crystallography, EXAFS spectroscopy analysis

A novel soft N and hard O donor combined ligand including N,N,N',N'-tetrakis(2-pyridylmethyl)-1,3- diaminopropane-2-amide structure (TPTNA) was successfully synthesized. Its structure and complexation of Eu³⁺ in solid state and methanol solution respectively were investigated by X-ray crystallography, UV-vis titration and EXAFS spectroscopy. As a result, the chemical stoichiometry of Eu³⁺ complex with TPTNA was determined to be 1 : 1 by X-ray crystallography. It was found that one amide unit, two pyridine groups from TPTNA coordinated with one Eu³⁺. However, the Eu-O and Eu-N bond lengths obtained from theoretical fitting of the EXAFS data were consistent with the results from X-ray crystallography studies, reflecting retention of the structure in methanol solution. (author)