Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La3+ and Nd3+) in Molten Salts

Molten salt electrolysis is a vital technique to produce high-purity lanthanide metals and alloys. However, the coordination environments of lanthanides in molten salts, which heavily affect the related redox potential and electrochemical properties, have not been well elucidated. Here, the competitive coordination of chloride and fluoride anions towards lanthanide cations (La³⁺ and Nd³⁺) is explored in molten LiCl-KCl-LiF-LnCl₃ salts using electrochemical, spectroscopic, and computational approaches. Electrochemical analyses show that significant negative shifts in the reduction potential of Ln³⁺ occur when F⁻ concentration increases, indicating that the F⁻ anions interact with Ln³⁺ via substituting the coordinated Cl⁻ anions, and confirm [LnCl_xF_y]^3−x−y (y_max=3) complexes are prevailing in molten salts. Spectroscopic and computational results on solution structures further reveal the competition between Cl⁻ and F⁻ anions, which leads to the formation of four distinct Ln(III) species: [LnCl₆]³⁻, [LnCl₅F]³⁻, [LnCl₄F₂]³⁻ and [LnCl₄F₃]⁴⁻. Among them, the seven-coordinated [LnCl₄F₃]⁴⁻ complex possesses a low-symmetry structure evidenced by the pattern change of Raman spectra. After comparing the polarizing power (Z/r) among different metal cations, it was concluded that Ln−F interaction is weaker than that between transition metal and F⁻ ions.     

Insertion Chemistry of Lutetacyclopropene toward Unsaturated C−O/C−N Bonds

Although the reaction chemistry of transition metallacyclopropenes has been well-established in the last decades, the reactivity of rare-earth metallacyclopropenes remains elusive. Herein, we report the reaction of lutetacyclopropene 1 toward a series of unsaturated molecules. The reaction of 1 with one equiv. of PhCOMe, Ar¹CHO (Ar¹=2,6-Me₂C₆H₃), W(CO)₆, and PhCH=NPh provided oxalutetacyclopentenes, metallacyclic lutetoxycarbene, and azalutetacyclopentene via 1,2-insertion of C=O, C≡O, or C=N bonds into Lu−C_sp2 bond, respectively. However, the reaction between 1 and Ar²N=C=NAr² (Ar²=4-MeC₆H₄) gave an acyclic lutetium complex with a diamidinate ligand by the coupling of one molecule of 1 with two carbodiimides, irrespective of the amount of carbodiimide employed. More interestingly, when 1 was treated with two equiv. of Ar¹CHO, the reductive coupling of two C=O bonds was discovered to give a lutetium pinacolate complex along with the release of tolan. Remarkably, the reactivity of 1 is significantly different from that of scandacyclopropenes; these metallacycles derived from 1 all represent the first cases in rare-earth organometallic chemistry.     

Synthesis and Biological Activities of Diosgenin-Triazole Conjugates with a 1,3-Dipolar Cycloaddition Reaction

Chemistry of Natural Compounds - A novel series of diosgenin-triazole conjugates (10a–d, 11a–c, 12a–c, 13a–c) was designed and synthesized as antifungal agents by using a...     

SYNTHESIS,CHARACTERIZATION, CRYSTAL STRUCTURE,AND DFT STUDY OF N-(2-METHOXY-5- (4,4,5,5-TETRAMETHYL-1,3,2-DIOXABOROLAN-2-YL) PYRIDIN-3-YL)CYCLOPROPANESULFONAMIDE

Journal of Structural Chemistry - N-(2-methoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-3-yl)cyclopropanesulfonamide is an organic intermediate with borate and sulfonamide groups,...     

Construction of Hybrid Bimetallic Uranyl Compounds Based on a Preassembled Terpyridine Metalloligand

Six hybrid uranyl–transition metal compounds [UO₂Ni(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 1 ), [UO₂Ni(cptpy)₂(BTPA)₂] ( 2 ), [UO₂Fe(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 3 ), [UO₂Fe(cptpy)₂(BTPA)₂] ( 4 ), [UO₂Co(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 5 ), and [UO₂Co(cptpy)₂(BTPA)₂] ( 6 ), based on bifunctional ligand 4′-(4-carboxyphenyl)-2,2′:6′,2′′-terpyridine (Hcptpy) are reported (H₂BTPA = 4,4′-biphenyldicarboxylic acid). Single-crystal XRD revealed that all six compounds feature similar metalloligands, which consist of two cptpy⁻ anions and one transition metal cation. The metalloligand M(cptpy)₂ can be considered to be an extended linear dicarboxylic ligand with length of 22.12 Å. Compounds 1 , 3 , and 5 are isomers, and all of them feature 1D chain structures. The adjacent 1D chains are connected together by hydrogen bonds and π–π interactions to form a 3D porous structure, which is filled with solvent molecules and can be exchanged with I₂. Compounds 2 , 4 , and 6 are also isomers, and all of them feature 2D honeycomb (6,3) networks with hexagonal units of dimensions 41.91×26.89 Å, which are the largest among uranyl compounds with honeycomb networks. The large aperture allows two sets of equivalent networks to be entangled together to result in a 2D+2D→3D polycatenated framework. Remarkably, these uranyl compounds exhibit high catalytic activity for cycloaddition of carbon dioxide. Moreover, the geometric and electronic structures of compounds 1 and 2 are systematically discussed on the basis of DFT calculations.     

干涉成像系统传递函数的数值分析

干涉仪系统传递函数能有效地表征系统相位成像的性能。通过假设干涉成像系统是复振幅的线性平移不变系统,模拟计算正弦相位光栅和相位台阶这两类标准相位物体的成像,确定干涉仪系统传递函数。数值分析结果表明：系统传递函数随着波像差的增加而减小;干涉成像系统对小幅度相位（远小于1 rad）成像是近似线性的,而对大幅度相位(大于0.5 rad）成像则是明显非线性的。当正弦相位的幅度为1时,系统传递函数在1/2和1/3截止频率处出现明显的急剧下降。高度为/2的相位台阶成像时,系统传递函数随着空间频率的增加而缓慢地降低。 The performance of phase imaging in interferometric imaging system is well characterized by the system transfer function (STF). The STF of the interferometric imaging system is analyzed numerically by assuming that the system is linear and shift-invariant for the complex field. Two standard phase objects, sinusoidal phase grating and phase step, are employed and simulated to determine the STF. Numerical simulation results show that the STF decreases as the wavefront aberration of interferometric imaging system increases. It also shows that the interferometric imaging system is approximately linear for small phase (far less than 1 rad) but explicitly nonlinear for large phase (larger than 0.5 rad). The STF has a visible drop at one half or one third of the cut-off frequency of the imaging system when the amplitude of sinusoidal phase is 1 rad. For a phase step with a height of /2 rad, the STF has no visible drop but decreases slowly with the increasing of spatial frequency. The results provide a useful guidance to the design of interferometer and the measurement of STF and power spectrum density in experiment.     

Design study and heat transfer analysis of a neutron converter target for medical radioisotope production

A worldwide challenge in the near future will be to find a way of producing radioisotopes in sufficient quantity without relying on research reactors. The motivation for this innovative work on targets lies in the accelerator-based production of radioisotopes using a neutron converter target as in the transmutation by adiabatic resonance crossing concept. Thermal analysis of a multi-channel helium cooled device is performed with the computational fluid dynamics code CFX. Different boundary conditions are taken into account in the simulation process and many important parameters such as maximum allowable solid target temperature as well as uniform inlet velocity and outlet pressure changes in the channels are investigated. The results confirm that the cooling configuration works well; hence such a solid target could be operated safely and may be considered for a prototype target.     

A Mesoporous Сarbon Prepared by Сarbonizing Cu(II)–p-Phenylenediamine Polymer for the Adsorption of Methyl Orange from Water

Russian Journal of Physical Chemistry A - A new mesoporous carbon containing nitrogen and copper was prepared by carbonizing a polymer obtained by blending p-phenylenediamine, copper(II) sulfate,...     

Observability inequality for the Petrovsky equation

The aim of this paper is to study the exact controllability of the Petrovsky equation. Under some checkable geometric assumptions, we establish the observability inequality via the multiplier method for the Dirichlet control problem.