title: Complexation behavior of Eu(III), Tb(III), Tm(III), and Am(III) with three 1,10-phenanthroline-type ligands: insights from density functional theory.
abstract: Extraction complexes of Eu(III), Tb(III), Tm(III), and Am(III) with three 1,10-phenanthroline-type ligands have been studied, primarily using density functional theory (DFT). The same accuracies and optimized structural geometries were obtained whether optimization of the [ML2(NO3)](2+) complexes was performed at the B3LYP/6-31G(d)/RECP or the MP2/6-31G(d)/RECP level of theory. Calculations carried out at the B3LYP/6-311G(d, p)/RECP level of theory indicated that solvation does not favor the formation of these complexes. Moreover, the ΔGg and ΔGsolv values for the reactions leading to the formation of [LnL2(NO3)](2+) complexes were seen to decrease with increasing atomic number of the lanthanide (from Eu to Tb to Tm). In addition, when a strongly hydrophobic benzo[e][1,2,4]triazine group was created in each ligand, ligand selectivity for actinides/lanthanides in acidic media improved. Even greater ligand selectivity for actinides/lanthanides in acidic media was obtained when a 5,6-diphenyl-1,2,4-triazine group was created in each ligand instead of a benzo[e][1,2,4]triazine group. Vibrational analysis and NMR spectroscopic analysis were also performed on all of the studied ligands and the metal complexes that included them. Further in-depth investigations should be undertaken in this field.
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900, China.
authors.forename: Yanqiu
authors.initials: Y
authors.lastname: Yang
authors.forename: Yu
authors.initials: Y
authors.lastname: Fang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Shiyuan
authors.initials: S
authors.lastname: Hu
authors.forename: Sheng
authors.initials: S
authors.lastname: Hu
authors.forename: Liang
authors.initials: L
authors.lastname: Yang
authors.forename: Dawei
authors.initials: D
authors.lastname: Wang
authors.forename: Huabei
authors.initials: H
authors.lastname: Zhang
authors.forename: Shunzhong
authors.initials: S
authors.lastname: Luo
mesh_terms: D000576:Americium / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D005063:Europium / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D010618:Phenanthrolines / Q000737:chemistry*; D011789:Quantum Theory; D013725:Terbium / Q000737:chemistry*; D013816:Thermodynamics; D013932:Thulium / Q000737:chemistry*; D014227:Triazines / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D010618:Phenanthrolines; D014227:Triazines; D013725:Terbium; D005063:Europium; D013932:Thulium; D000576:Americium; C025205:1,10-phenanthroline