Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), N_2 adsorption/desorption experiments, powder X-ray diffraction(PXRD), and thermogravimetric analysis(TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at p H 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO_3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).
We used density functional theory calculations at the B3LYP/6-311G** level for a theoretical study on the complex formed when uranium(Ⅳ) coordinates with N,N'- bis(3-allyl salicylidene)-o-phenylenediamine(BASPDA),i.e.,U(BASPDA)_2.The results indicated that the coordination complex of U(BASPDA)2 could form two different structures with a ratio of 1:2.One was a parallel dislocation structure(PDS-U),in which the two BASPDAs' middle benzene rings adopted a parallel dislocation with an angle of 56.64°,and the other was a staggered finger "+" structure(SFS-U),in which the two BASPDAs employed the staggered finger "+" shape.The binding energies,charge distribution,spectral properties,thermodynamic properties,molecular orbitals and Wiberg bond indices for both PDS-U and SFS-U were calculated and compared with each other.
Wen-Bo LanSha GaoYing-Wu LinGuo-Wen PengChang-Ming Nie
基于密度泛函理论（DFT）计算方法,对铀酰-Salophen与四氢吡咯及水分子之间形成的氢键进行了理论计算及分析.结果表明体系1和体系2中的氢键键长都小于0.228 nm,键角都在160°-178°之间,体系1中Salophen的O1与四氢吡咯上的H1之间的氢键相互作用能EHB=-10.658 k J/mol,在体系2中铀酰的O3与四氢吡咯上的H3及O1与H1之间的氢键相互作用能分别为EHB=-7.989 k J/mol、EHB=-11.114 k J/mol,铀酰-Salophen中的C-O和U=O均可与四氢吡咯形成氢键,且C-O…H-N稳定性大于U=O…H-N.
Understanding uranium-protein interaction is important for revealing the mechanism of uranyl ion(UO2+2)toxicity. In this study, we investigated the interaction between UO2+2and a quadruple mutant of cytochrome b5(E44/48/56A/D60 A cyt b5, namely 4A cyt b5) by spectroscopic approaches. The four mutated negativelycharged surface residues of cyt b5 have been considered to be the interactive sites with cytochrome c(cyt c).Also, we studied the interaction between UO2+2and the protein-protein complex of 4A cyt b5-cyt c. The results were compared to the interaction between UO2+2and cyt b5, and the interaction between cyt c and cyt b5-cyt c complex, from previous studies. It was found that the interaction of UO2+2-cyt b5, i.e., uranyl ion binding to cyt b5 surface at Glu37 and Glu43 as previously proposed by molecular modeling, is regulated by both surface mutations of cyt b5 and its interacting protein partner cyt c. These provide valuable information on metal-protein-protein interactions and clues for understanding the mechanism of uranyl toxicity.
