Differentiation and dating of red ink entries of seals on documents by HPLC and GC/MS

A novel approach for differentiation and dating of red ink entries of seals on documents was developed based on ion‐pairing HPLC (IP‐HPLC) and GC/MS. Sixty‐nine red ink pastes of seals were collected and the chromatographic conditions for separation of the dye components by IP‐HPLC and the volatile additives by GC/MS in the ink entries were optimized. According to the dye components and additives, the ink entries were classified by HPLC with a multi‐wavelength UV detector. The volatile components of the inks were identified by GC/MS and the classification of the ink entries was also investigated based on these volatile additives. The results showed that most of the ink entries of the seals can be differentiated by combining HPLC with a multi‐wavelength detector and GC/MS methods. The degradation of the standard dye mixtures and the compositional changes of the ink entries of seals were investigated in light or natural aging conditions. The results indicated that the dye components decomposed in light or natural storage conditions, while the rates of the degradation depended on the structures of the dye components, the aging conditions, even the additives of the ink pastes. The results also showed that there existed good relationships between the compositional changes of the ink entries and the aging time, which can provide scientific evidences and valuable clues for dating of the ink entries.     

Self-assembly of two zinc complexes with flexible building block of 4-pyridylthioethylphosphonate

A new organophosphonate ligand containing sulfide group, 4-pyridylthioethylphosphonic acid hydrobromide (H₂pytep·HBr), is synthesized through a facile route. Two zinc complexes of Zn₂(pytepH₂)₂Br₄ (1) and [Zn(pytep)]·H₂O (2) are obtained by reacting H₂pytep·HBr with zinc nitrate in solution and under hydrothermal condition, respectively. X-ray crystallographic studies reveal that 1 has a dinuclear structure in which the equivalent Zn atoms are doubly bridged by phosphonate groups. Compound 2 has a layer structure where ladder-like chains made up of corner-sharing {ZnNO₃} and {CPO₃} tetrahedra are linked by the organic groups of pytep. Photoluminescent properties are investigated. Different from complex 1 which shows no photoluminescence, complex 2 exhibits photoluminescence at 468 nm (λ_ex = 353 nm) in the solid state at room temperature.     

A new route for simple and rapid determination of hydrogen peroxide in RAW264.7 macrophages by microchip electrophoresis

A new method using MCE with LIF detection was developed for the determination of hydrogen peroxide (H₂O₂). Bis(p‐methylbenzenesulfonyl)dichlorofluorescein, a new fluorogenic reagent synthesized by our laboratory was employed as a labeling reagent, the derivatization reaction was performed in 0.10 M HEPES buffer (pH 7.4) for 30 min at 37°C. The detection of H₂O₂ was accomplished in 55 s, using a 40 mM HEPES buffer, 20% mannitol, pH 7.4, on a glass microchip. The RSDs of migration time and peak area were 1.8 and 3.7%, respectively. Method validation showed the linear response ranging from 0.50 to 50 μM with an LOD (S/N=3) of 0.20 μM (19.1 amol). The proposed method was applied to determine H₂O₂ in phorbol myristate acetate‐stimulated RAW264.7 macrophages, the concentration of H₂O₂ was found to be 1.86±0.05 μM; recoveries for macrophage samples were from 96.7 to 97.8%, within‐days and between‐days accuracies were 4.5% (n=5) and 6.8% (n=5), respectively.     

A Rapid Method for the Analysis of Ten Compounds in Psoralea corylifolia L. by UPLC

The objective of this study was to develop a simple, efficient and reliable method for routine quantitative analysis for Psoralea corylifolia L. An ultra performance liquid chromatography with DAD detector system was employed for simultaneous quantification of ten compounds. The chromatographic analysis was performed by UPLC with C₁₈ column and gradient elution of 0.05% formic acid aqueous solution and acetonitrile in 16 min. All calibration curves were linear (R ² ≥ 0.9990) over the tested ranges. The LOD and LOQ were lower to 13.07 and 39.22 ng mL^?1 with 2 μL of injection volume, respectively. The intra- and inter-day precisions as determined from sample solutions were below 4.1 and 4.2%. The average recoveries were ranged from 94.2 to 108.8% with RSDs ≤ 4.6%. This validated method was applied for the analysis of ten analytes in P. corylifolia L. from different origins. The variation of the content of ten compounds was remarkable among the tested samples: psoralenoside increased from 7.42 to 17.04 mg g^?1, isopsoralenoside from 6.05 to 14.34 mg g^?1, psoralen from 2.37 to 3.90 mg g^?1, isopsoralen from 2.53 to 3.65 mg g^?1, neobavaisoflavone from 1.59 to 2.96 mg g^?1, bavachin from 1.02 to 2.35 mg g^?1, psoralidin from 0.45 to 1.91 mg g^?1, isobavachalcone from 1.33 to 4.71 mg g^?1, corylifol A from 1.02 to 2.40 mg g^?1 and bakuchiol from 28.10 to 63.89 mg g^?1.     

Investigation on the photophysical processes in nanosized photocatalytic thin films using planar solid-state devices

The photophysical processes for three nanosized photocatalytic oxides, titanium dioxide (TiO₂) thin film, tin dioxide (SnO₂) thin film, and layered TiO₂/SnO₂ thin film, have been examined in planar solid-state devices. It is found that, for SnO₂ thin film, the dissociation of the photogenerated excitons can take place both on the film surface and inside the film, while for TiO₂ thin film, almost all excitons dissociate on the film surface. Such a difference is proposed to account for the higher photocatalytic activity of TiO₂ over SnO₂, since it is experimentally shown that the excitons dissociate in SnO₂ thin film as efficiently as they do in TiO₂ thin film. For layered TiO₂/SnO₂ thin film, when it is illuminated by a beam of UV light, it is suggested that there exists a local electrostatic field at the SnO₂ side of the interface, mainly formed by those holes efficiently photogenerated and then localized in SnO₂ thin film. The photo-induced local electrostatic field is believed to facilitate hole–electron separation on TiO₂ thin film and therefore increase the photocatalytic activity of the layered thin film over single TiO₂ thin film.     

3-仲氨基氧杂环丁烷-3-腈衍生物的合成

以仲胺、氧杂环丁-3-酮和三甲基氰硅烷为原料,无水甲醇为溶剂,无需催化剂,一步反应合成目标化合物3-仲氨基氧杂环丁烷-3-腈衍生物(1a～1d),产物结构经¹H NMR、¹³C NMR和ESI-MS表征。并以异吲哚啉、氧杂环丁-3-酮和三甲基氰硅烷的反应为模型反应,考察影响产物1a收率的主要因素,优化反应条件为:物料摩尔比为n(异吲哚啉)∶n(氧杂环丁-3-酮)∶n(三甲基氰硅烷)=2.0∶1∶2.5;反应溶剂为无水甲醇,在65℃反应6h,在此反应条件下,化合物1a收率78.3%。化合物1a与苯基溴化镁在四氢呋喃中室温反应5h,可得到2-(3-苯基氧杂环丁烷-3-基)异吲哚啉(4)和[3-(异吲哚啉-2-基)氧杂环丁烷-3-基](苯基)甲酮(5),收率分别为40.1%和31.5%。     

Imine Gels Based on Ferrocene and Porphyrin and Their Electrocatalytic Property

A series of porphyrin‐based imine gels have been synthesized via dynamic covalent gelation between 5,10,15,20‐tetra(4‐aminophenyl)‐21H,23H‐porphyrin (H₂TAPP) derivatives and various aldehyde compounds. The porphyrin‐ferrocene imine gels based on MTAPP (M=H₂, Ni²⁺, Co²⁺, Pd²⁺ and Zn²⁺) and ferrocene‐1,1′‐dicarbaldehyde (NA) display efficient HER, OER and ORR activities in alkaline media. Among the gels, CoTAPP‐NA shows an HER current density of 10 mA cm^?2 at low overpotential of 470 mV and small Tafel slope of 110 mV decade^?1 in alkaline media. CoTAPP‐NA also exhibits OER catalytic activity with low overpotential (416 mV for 10 mA cm^?2). CoTAPP‐NA shows ability in overall water splitting in alkaline media. In addition, CoTAPP‐NA exhibits onset potential (E_p) of 0.95 V and half‐wave potential (E_1/2) of 0.84 V in 1.0 mol L^?1 KOH solution for oxygen reduction. Moreover, the gel catalyst shows good stability.     

Regulation of Cathode‐Electrolyte Interphase via Electrolyte Additives in Lithium Ion Batteries

As the power supply of the prosperous new energy products, advanced lithium ion batteries (LIBs) are widely applied to portable energy equipment and large‐scale energy storage systems. To broaden the applicable range, considerable endeavours have been devoted towards improving the energy and power density of LIBs. However, the side reaction caused by the close contact between the electrode (particularly the cathode) and the electrolyte leads to capacity decay and structural degradation, which is a tricky problem to be solved. In order to overcome this obstacle, the researchers focused their attention on electrolyte additives. By adding additives to the electrolyte, the construction of a stable cathode‐electrolyte interphase (CEI) between the cathode and the electrolyte has been proven to competently elevate the overall electrochemical performance of LIBs. However, how to choose electrolyte additives that match different cathode systems ideally to achieve stable CEI layer construction and high‐performance LIBs is still in the stage of repeated experiments and exploration. This article specifically introduces the working mechanism of diverse electrolyte additives for forming a stable CEI layer and summarizes the latest research progress in the application of electrolyte additives for LIBs with diverse cathode materials. Finally, we tentatively set forth recommendations on the screening and customization of ideal additives required for the construction of robust CEI layer in LIBs. We believe this minireview will have a certain reference value for the design and construction of stable CEI layer to realize desirable performance of LIBs.     

Silicon Carbide Supported Palladium‐Iridium Bimetallic Catalysts for Efficient Selective Hydrogenation of Cinnamaldehyde

Selective hydrogenation of α,β‐unsaturated carbonyls into saturated carbonyls is important to obtain remunerative products. However, it is still a challenge to achieve high activity and selectivity under mild conditions. Herein, Pd, Ir and bimetallic Pd‐Ir nanoparticles were uniformly deposited with high dispersity on the surface of SiC by a facile impregnation method, respectively. The as‐prepared Pd/SiC catalysts efficiently hydrogenate cinnamaldehyde to hydrocinnamaldehyde at room temperature and atmospheric pressure, and the activity of Pd/SiC is observed further enhanced by adding Ir component (conversion of 100%). In addition, the dependence of Pd‐Ir catalyst activity on Pd/Ir molar ratio confirms a synergistic effect between Ir and Pd, which originates from the electron transfer between Pd and Ir.     

Synthesis of Electron‐Deficient Corona[5]arenes and Their Selective Complexation with Dihydrogen Phosphate: Cooperative Effects of Anion–π Interactions

Reported here are the syntheses, conformational structures, electrochemical properties, and noncovalent anion binding of corona[5]arenes. A (3+2) fragment coupling reaction proceeded efficiently under mild reaction conditions to produce a number of novel heteroatom‐ and methylene‐bridged corona[3]arene[2]tetrazine macrocycles. Selective oxidation of the sulfur atom between two phenylene rings afforded sulfoxide‐ and sulfone‐linked corona[5]arenes in good yields. All corona[5]arenes synthesized adopted similar 1,2,4‐alternate conformational structures, forming pentagonal cavities. The cavity sizes and the electronic properties such as redox potentials, were measured with CV and DPV, and were influenced by the different bridging units. As electron‐deficient macrocycles, the acquired corona[3]arene[2]tetrazines served as highly selective hosts, forming complexes with the hydrogen‐bonded dimer of dihydrogen phosphate through cooperative anion–π interactions.