Amino-Acid-Induced Circular Polarized Luminescence in One-Dimensional Manganese(II) Halide Hybrid

Circular polarized luminescence (CPL)-active materials attract great attentions owing to their widely applications in 3D optical displays and encrypted transmission. Inspired by the strategies adopted in perovskite based CPL materials, herein, CPL-active hybrids (D)- and (L)-(tert-butyl prolinate)MnCl₃ were successfully prepared by assembling chiral D/L tert-butyl prolinate with manganese (II) chloride. Single crystal structures show the as-formed hybrids possess one-dimensional (1D) structure containing linear chains of face-sharing MnCl₆ octahedral surrounded by prolinate cations. The 1D Mn(II) hybrids display strong red emission peaked at 646 nm with PLQY of 67.1 % and 57.2 % for d -type and l -type, respectively, representing the highest PLQY for 1D Mn^II hybrids. Interestingly, the 1D Mn(II) hybrids exhibit prominent circular dichroism (CD) signals and remarkable CPL activity with the dissymmetry factor g of 6.1*10⁻³ and −6.3*10⁻³ from 550 to 800 nm for (D)- and (L)-(tert-butyl prolinate)MnCl₃, respectively, owing to the existence of chiral cations. It is worthy noted the obtained g represents the highest value for non-lead organic–inorganic hybrids.     

Photoionization and Dissociation Study of 2-Methyl-2-propen-1-ol: Experimental and Theoretical Insights

The photoionization and dissociation of 2-methyl-2-propen-1-ol (MPO) have been investigated by using molecular beam experimental apparatus with tunable vacuum ultravioletsynchrotron radiation in the photon energy region of 8.0-15.5 eV. The photoionization efficiency (PIE) curves for molecule ion and fragment ions: C₄H₈O⁺、C₄H₇O⁺、C₃H₅O⁺、C₄H₇⁺、C₄H₆⁺、C₄H₅⁺、C₂H₄O⁺、C₂H₃O⁺、C₃H₆⁺、C₃H₅⁺、C₃H₃⁺、CH₃O⁺、CHO⁺ have been measured, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions have been obtained. The stable species and the first order saddle points have been calculated on the CCSD(T)/cc-pvTZ//B3LYP/6-31+G(d,p) level. With combination of theoretical and experimental results, the dissociative photoionization pathways of 2-methyl-2-propen-1-ol are proposed. Hydrogen migrations within the molecule are the dominant processes in most of the fragmentation pathways of MPO.     

Kinetics Study on Reaction between Dihydroartemisinic Acid and Singlet Oxygen: An Essential Step to Photochemical Synthesis of Artemisinin

Artemisinin is an excellent antimalarial drug widely used in clinical medicine. However, due to the limitation of natural source of artemisinin, the chemical synthesis of artemisinin has achieved substantial attention. Dihydroartemisinic acid is a key precursor for the synthesis of artemisinin. The reaction of dihydroartemisinic acid with singlet oxygen to form peroxide is a pivotal step in the photochemical preparation of artemisinin. Nevertheless, the reaction kinetics of dihydroartemisinic acid with singlet oxygen has not been investigated previously. Herein, we report the rate constants of the reaction between dihydroartemisinic acid and singlet oxygen. By directly detecting the luminescence decay kinetics of singlet oxygen at 1270 nm at room temperature, the reaction rate constants of singlet oxygen and dihydroartemisinic acid in different solvents are obtained to be 1.81\begin{document}$\times$\end{document}10\begin{document}$^5$\end{document} (mol/L)^-1·s^-1 in CCl\begin{document}$_4$\end{document}, 5.69\begin{document}$\times$\end{document}10\begin{document}$^5$\end{document} (mol/L)^-1·s^-1 in CH\begin{document}$_3$\end{document}CN, and 3.27\begin{document}$\times$\end{document}10\begin{document}$^6$\end{document} (mol/L)^-1·s^-1 in DMSO, respectively. It is found that the reaction rate constants of dihydroartemisinic acid with singlet oxygen increase as polarity of the solvent increases among the three solvents. These results provide fundamental knowledge to optimize experiment conditions of photochemical synthesis of artemisinin for improving the yields of artemisinin.     

A Single-Atom Manipulation Approach for Synthesis of Atomically Mixed Nanoalloys as Efficient Catalysts

Synthesis of well-defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single-atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO₂ as a carrier and transition-metal single atoms as an intermediate state. The supported nanoalloys/CeO₂ with ultra-low noble metal content (containing 0.2 wt % Au and 0.2 wt % Pt) exhibit enhanced catalytic performance towards complete CO oxidation at room temperature and remarkable thermostability. This work provides a general strategy for facile and rapid synthesis of well-defined atomically mixed nanoalloys that can be applied for a range of emerging techniques.     

In Situ Anchoring of Pyrrhotite on Graphitic Carbon Nitride Nanosheet for Efficient Immobilization of Uranium

Enrichment of U^VI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe₇S₈) on the graphitic carbon nitride nanosheet (CNNS), which were used for capturing U^VI. The structural characterizations of Fe₇S₈/CNNS-1 indicated that the CNNS could prevent the aggregation of Fe₇S₈ and the saturation magnetization was 4.69 emu g⁻¹, which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g⁻¹ at 298 K. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: U^VI is adsorbed on the surface of Fe₇S₈/CNNS-1 through surface complexation initially, then it was reduced to insoluble U^IV. Thereby, this work provided an efficient and easy to handle sorbent material for extraction of U^VI.     

Light Lanthanide Metallocenium Cations Exhibiting Weak Equatorial Anion Interactions

As the dysprosocenium complex [Dy(Cp^ttt)₂][B(C₆F₅)₄] (Cp^ttt=C₅H₂tBu₃-1,2,4, 1-Dy ) exhibits magnetic hysteresis at 60 K, similar lanthanide (Ln) complexes have been targeted to provide insights into this remarkable property. We recently reported homologous [Ln(Cp^ttt)₂][B(C₆F₅)₄] ( 1-Ln ) for all the heavier Ln from Gd–Lu; herein, we extend this motif to the early Ln. We find, for the largest Ln^III cations, that contact ion pairs [Ln(Cp^ttt)₂{(C₆F₅-κ¹-F)B(C₆F₅)₃}] ( 1-Ln ; La–Nd) are isolated from reactions of parent [Ln(Cp^ttt)₂(Cl)] ( 2-Ln ) with [H(SiEt₃)₂][B(C₆F₅)₄], where the anion binds weakly to the equatorial sites of [Ln(Cp^ttt)₂]⁺ through a single fluorine atom in the solid state. For smaller Sm^III, [Sm(Cp^ttt)₂][B(C₆F₅)₄] ( 1-Sm ) is isolated, which like heavier 1-Ln does not exhibit equatorial anion interactions, but the Eu^III analogue 1-Eu could not be synthesised due to the facile reduction of Eu^III precursors to Eu^II products. Thus with the exception of Eu and radioactive Pm this work constitutes a structurally similar family of Ln metallocenium complexes, over 50 years after the [M(Cp)₂]⁺ series was isolated for the 3d metals.     

Design and fabrication of 2 kHz nematic liquid crystal variable retarder with reflection mode

ABSTRACT

This study proposes a simple method of designing a high-speed liquid crystal variable retarder (LCVR) with reflection mode. First, a series of simple formulas is provided for analysing the effects of tilt incidence and birefringence of the liquid crystal on the phase retardation and response time of the LCVR. Then, a reflective LCVR is fabricated to validate the theoretical analysis. Measured results show that the response speed can reach 2.7 kHz with a phase retardation of 1 λ. Furthermore, the theoretical curve is close to the measured curve while the incident angle is less than 10°. However, the theoretical and measured values show a considerable difference under a large incident angle. This problem is discussed, and a modified method is given. This work is helpful for the design and fabrication of high-speed LCVR.     

Porous surfur-doped hard carbon for excellent potassium storage

Hard carbon is promising anode for potassium-ion batteries(PIBs),however,the poor rate capability hinders its development as potential anode.To address this question,we design a sulfur-doped porous hard carbon(S-HC)for PIBs through the combination of structural design and composition adjustment.The as-designed S-HC exhibits a long cycling life with^191 mAh/g after 300 cycles at 1 A/g,and an excellent rate capability with^100 mAh/g at 5 A/g,which was attributed to its structural characteristics and compositions.The S-HC demonstrates to be promising anode in the future.     

蛋白质的微乳液毛细管电动色谱分离研究

考察了用微乳液毛细管电动色谱(MEEKC)分离蛋白质时微乳液组成等不同因素对分离的影响,并与胶束电动色谱进行对比,探讨了其分离机理,为蛋白质的分离鉴定提供了一种有力的工具.     

Two New Diterpenoids from Isodon rubescens

In order to further study on minor diterpenoid constituents of lsodon rubescens, wereinvestigated this species, which was collected in Taibai mountain, Shaanxi Province.TWo new diterpenoids, taibairubescensins A (l) and B (2), were isolated. In this paper,we present the structure elucidation of these two new diterpenoids.Taibairubescensin A (l ), C,.H,#O, (FABMS m/z 435[M 11 ), an amorphous powder,showed UV and iR absorption bands for the existence of hydroxyl, acetoxyl and a fivemembe…