Complexation of U(VI) with BiPDA, DmBiPDA, and PhenDA: Comparison on Structures and Binding Strengths in Aqueous and DMSO/20%(v)H2O Solutions

Autor:	Linfeng Rao, Yanqiu Yang, Jun Liu, Liang Yang, Zhicheng Zhang, Chao Xu, Shunzhong Luo
Rok vydání:	2019
Předmět:	Steric effects Denticity Aqueous solution 010405 organic chemistry Ligand Solvation 010402 general chemistry Uranyl 01 natural sciences 0104 chemical sciences Inorganic Chemistry Bond length chemistry.chemical_compound Crystallography chemistry Carboxylate Physical and Theoretical Chemistry
Zdroj:	Inorganic Chemistry. 58:6064-6074
ISSN:	1520-510X 0020-1669
Popis:	The stability constants (log β) of 1:1 uranyl complexes with three N,O-mixed donor ligands (L = 2,2'-dipyridyl-6,6'-dicarboxylate, 3,3'-dimethyl-2,2'-bipyridine-6,6'-dicarboxylate, and 1,10-phenanthroline-2,9-dicarboxylate, denoted as BiPDA, DmBiPDA, and PhenDA, respectively) in aqueous and DMSO/20%(v)H2O solutions were determined by spectrophotometry in 0.1 M tetraethylammonium perchlorate. The effects of ligand preorganization, steric hindrance, and solvation on the binding strength of U(VI) with the three ligands were discussed. In aqueous solution, PhenDA forms stronger complexes with U(VI) than BiPDA due to its well-preorganized structure. In DMSO/20%(v)H2O solution, in contrast, the strong solvation effect of DMSO on the ligands reduces the energy gap between the trans- and cis-conformations of BiPDA, resulting in log β(UO2(BiPDA)) > log β(UO2(PhenDA)). The steric hindrance of methyl groups on DmBiPDA makes the complex UO2(DmBiPDA) of the lowest stability in both aqueous and DMSO/20%(v)H2O solutions. Single-crystal structural data of U(VI) complexes with the three ligands indicate that the ligand coordinates with UO22+ via aromatic nitrogen atoms and carboxylate oxygen atoms. There is no clear correlation between the trend of the stability constants in solutions and the U-N/O bond lengths of the three crystal complexes. Nevertheless, DmBiPDA coordinates to UO22+ in a high-strain fashion as a result of the steric hindrance of methyl groups while BiPDA in a low-strain fashion, which is in accordance with the relative complexation strength of the two respective complexes. The results from this work help us understand the effect of ligand preorganization and solvation on the binding strength of actinides with multidentate N,O-mixed ligands in solid and solutions, which is of importance in designing ligands for the partitioning of actinides from nuclear wastes.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::d6ace56ca78bf8956ec8b143114ab51c https://doi.org/10.1021/acs.inorgchem.9b00319 Zobrazit plný text záznamu