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491.
《Particuology》2023
Ultrasound-assisted synthesis of Mn/Co-MOF nanomaterial was used to capture uranium from aqueous solutions. Tests of Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared spectra (FT-IR), Zeta potential analysis, thermogravimetric analysis (TGA), and X-ray diffraction (XRD) suggest that cobalt ions were replaced partially by manganese ions to generate MOF during the synthesis process and form manganous oxide particles loaded on the surface of Mn/Co-MOF. The optimal immobilization conditions of U(VI) were systematically studied by solution pH, kinetic, contact time and preparatory uranium concentration. XPS spectroscopy analysis indicated that the chelation of imidazole ring to uranium and Mn3O4 possibly played a certain role in the adsorption process. The results indicate that the adsorption isotherms of the Mn/Co-MOF for uranium suit Langmuir isotherm model (maximum adsorption capacity were 763.36 mg/g). Furthermore, the adsorption kinetics of Mn/Co-MOF match comfortably with the pseudo-second-order kinetic model. 相似文献
492.
Zuowei Xie Chaoguo Yan Qingchuan Yang Thomas C. W. Mak 《Angewandte Chemie (International ed. in English)》1999,38(12):1761-1763
The tetranion ligand η7-C2B10H124− has been observed for the first time in 1 , which was obtained from the reaction of o-C2B10H12 with excess K metal followed by treatment with UCl4. As shown in the picture (without K cations and coordinated THF molecules), 1 is a centrosymmetric dimer with a bent sandwich structure. 相似文献
493.
Benjamin P. Warner Brian L. Scott Carol J. Burns 《Angewandte Chemie (International ed. in English)》1998,37(7):959-960
In clean, one-pot procedures , the uranium complex 1 reductively cleaves azides and azo compounds to generate bis(imido) derivatives [Eq. (a)]. This unusual reaction has not been observed previously in either the actinide series or with a metallocene complex. 相似文献
494.
Julia G. Knapp Dr. Xijun Wang Dr. Andrew S. Rosen Xingjie Wang Dr. Xinyi Gong Dr. Matthew Schneider Dr. Tatyana Elkin Dr. Kent O. Kirlikovali Dr. Melissa Fairley Dr. Matthew D. Krzyaniak Prof. Michael R. Wasielewski Prof. Nathan C. Gianneschi Prof. Randall Q. Snurr Prof. Omar K. Farha 《Angewandte Chemie (International ed. in English)》2023,62(29):e202305526
The interactions between uranium and non-innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium-based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self-assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non-innocent linkers. We report the synthesis of the MOF NU-1700 , assembled from U4+-paddlewheel nodes and catecholate-based linkers. We propose this highly unusual structure, which contains two U4+ ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X-ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations. 相似文献
495.
Jinghang Shen Thayalan Rajeshkumar Genfeng Feng Yue Zhao Shuao Wang Laurent Maron Congqing Zhu 《Angewandte Chemie (International ed. in English)》2023,62(21):e202303379
Although examples of multiple bonds between actinide elements and main-group elements are quite common, studies of the multiple bonds between actinide elements and transition metals are extremely rare owing to difficulties associated with their synthesis. Here we report the first example of molecular uranium complexes featuring a cis-[M U M] core (M=Rh, Ir), which exhibits an unprecedented arrangement of two M U double dative bond linkages to a single U center. These complexes were prepared by the reactions of chlorine-bridged heterometallic complexes [{U{N(CH3)(CH2CH2NPiPr2)2}(Cl)2[(μ-Cl)M(COD)]2}] (M=Rh, Ir) with MeMgBr or MeLi, a new method for the construction of species with U−M multiple bonds. Theoretical calculations including dispersion confirmed the presence of two U M double dative bonds in these complexes. This study not only enriches the U M multiple bond chemistry, but also provides a new opportunity to explore the bonding of actinide elements. 相似文献
496.
Tongyu Li Dongwei Wang Yi Heng Dr. Guohua Hou Prof. Guofu Zi Dr. Wanjian Ding Prof. Dr. Laurent Maron Prof. Dr. Marc D. Walter 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313010
Uranium diazomethanediide complexes can be prepared and their synthesis, structure and reactivity were explored. Reaction of the uranium imido compound [η5-1,2,4-(Me3Si)3C5H2]2U=N(p-tolyl)(dmap) ( 1 ) or [η5-1,3-(Me3C)2C5H3]2U=N(p-tolyl)(dmap) ( 4 ) with Me3SiCHN2 cleanly yields the first isocyanoimido metal complexes [η5-1,2,4-(Me3Si)3C5H2]2U(=NNC)(μ-CNN=)U(dmap)[η5-1,2,4-(Me3Si)3C5H2]2 ( 2 ) and {[η5-1,3-(Me3C)2C5H3]2U[μ-(=NNC)]}6 ( 5 ), respectively. Both compounds exhibit remarkable thermal stability and were fully characterized. According to density functional theory (DFT) studies the bonding between the Cp2U2+ and [NNC]2− moieties is strongly polarized with a significant 5 f orbital contribution, which is also reflected in the reactivity of these complexes. For example, complex 5 acts as a nucleophile toward alkylsilyl halides and engages in a [2+2] cycloaddition with CS2, but no reaction occurs in the presence of internal alkynes. 相似文献
497.
The laser-induced fluorescence excitation spectra of uranium monofluoride have been recorded in the range of 17000\begin{document}$ - $\end{document} 19000 cm\begin{document}$^{-1} $\end{document} using two-dimensional spectroscopy. High resolution dispersed fluorescence spectra and time-resolved fluorescence spectroscopy were also recorded. Three rotationally resolved bands were intensively analyzed, and all bands were found to be derived from the ground state X(1)4.5 with a rotational constant of 0.23421 cm\begin{document}$^{-1} $\end{document} . The low-lying electronic states were observed near 435 and 651 cm\begin{document}$^{-1} $\end{document} in the dispersed fluorescence spectra, which were assigned as \begin{document}$ \Omega' $\end{document} =3.5 and 2.5, respectively. The vibrational constants for the X(1)4.5 and X(1)3.5 states were calculated. The branching ratios of the dispersed fluorescence spectra for the [18.62]3.5, [17.72]4.5, and [17.65]4.5 states were reported. Radiative lifetime of 332(9) ns, 825(49) ns, and 433(15) ns for the [18.62]3.5, [17.72]4.5, and [17.65]4.5 states were obtained by fitting the time-resolved fluorescence spectroscopy, respectively. Transition dipole moments were performed using the branching ratios and the radiative lifetimes. 相似文献
498.
Junyi Wang Shuai Zhu Dr. Wangyang Ma Prof. Dr. Zhenyang Lin Prof. Dr. Qing Ye 《Angewandte Chemie (International ed. in English)》2023,62(27):e202219062
BN-butafulvenes, mono-BN isosteres of butafulvene and highly strained isomers of azaborines and B-amino boroles, have been synthesized via hydrolysis of the urana-borabicyclic complexes obtained from the reactions of bis(alkynyl)boranes with an uranacyclopropene complex. Their 4-dimethylaminopyridine (DMAP) adducts can further isomerize to 1,2,4,6-multisubstituted BN-9,1-naphthalenes. Both NMR reaction monitoring and theoretical calculations point to a reaction mechanism involving dearomative insertion of DMAP followed by two consecutive 1,2-hydrogen shifts. The photophysical studies of the highly substituted BN-9,1-naphthalenes reveal a notable redshift in both the UV/Vis absorption and emission spectra. The (TD)-DFT calculations corroborate the experimental data, suggesting that the strong π-donating amino substitution at the 1- and/or 6-positions destabilizes the HOMO, and thus leading to a notable decrease of the HOMO–LUMO gap. 相似文献