Table of Content

10 July 2020, Volume 41 Issue 7

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Contents

Cover and Content of Chemical Journal of Chinese Universities Vol.41 No.7(2020)

2020, 41(7):  0-0. 

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Review

Visible-light-promoted Dearomatization of Benzene and Derivatives^†

ZHU Min, ZHANG Xiao, YOU Shuli

2020, 41(7):  1407-1414.  doi:10.7503/cjcu20200205

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Benzene rings are widely found in petrochemicals, which are cheap and readily available. Compared with other (hetero)aromatic rings, the dearomatization of benzene rings is more challenging as benzene is more stable. On the other hand, visible-light photocatalysis has experienced rapid development since last decade. Upon visible-light irradiation, highly active intermediates are formed to break aromatic stability and to construct three-dimensional molecules from flat compounds. In this review, recent examples on visible-light-promoted dearomatization of benzene and derivatives are summarized, which can be divided into two main categories: ground-state chemistry and excited-state chemistry. The perspective for future development of this field is also discussed.



Biomimicry of Cellular Membrane with Framework Nucleic Acids^†

YAN Lei, MAO Xiuhai, ZUO Xiaolei

2020, 41(7):  1415-1425.  doi:10.7503/cjcu20200251

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Biomimicry of cellular membrane is crucial for the study of cellular communications and transportation, and holds great potentials in various applications, including nanomedicine, nanopore based single molecule detection, cell imaging, drug delivery and cancer therapy. Owing to its ability to nanoscale precisely shape and manipulation, construction of framework nuclei acids(FNAs) provides a promising approach to bio-mimicking cellular membrane proteins and exploiting their functions and applications. In this review, we introduce the structure and imaging technology for FNAs as well as assembling methods for FNAs based artificial cellular membrane in recent years. In addition, the application fields as well as the existing opportunities and challenges of FNAs based biomimicry of cellular membrane are discussed.



Recent Advances of Catalytic Asymmetric C—B Bond Forming Reactions^†

HUANG Mingyao, ZHU Shoufei

2020, 41(7):  1426-1448.  doi:10.7503/cjcu20200090

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Organoboron compounds are of particular importance in the fields of synthesis, pharmaceutical and material sciences. With retention of the absolute configuration, a boryl group can be easily transformed into another functional group, which make chiral organoborons versatile reagents in synthetic chemistry. On the other side, chiral organoborons can serve as drugs or bioactive molecules and applied for the diagnosis and treatment of many diseases. Given these functions, methods for the synthesis of chiral organoboron compounds are intensively investigated in the field of organic synthesis. Herein, we reviewed the recent progresses on the catalytic asymmetric C—B bond forming reactions.



Recent Progress in Electrochemical Catalytic Conversion of Biomass Platform Molecules into High-value Added Fuels and Chemicals^†

ZHOU Hua, LI Zhenhua, KONG Xianggui, DUAN Haohong

2020, 41(7):  1449-1460.  doi:10.7503/cjcu20200212

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Biomass, as an abundant renewable carbon resource, is a promising alternative to fossil carbon for producing fuels and chemicals. As a green and effective strategy, electrocatalytic biomass valorization is emerging as an important frontier research area for feasible biorefinery. In this review, we summarize the recent progress in electrocatalytic upgrading of biomass platform chemicals via redox and coupling reactions, highlighting the understanding of reaction mechanisms and the structure-function relationships of catalysts. Moreover, the future of electrochemical technologies for biomass valorization is prospected.



Articles

Multifunctional DNA Nanoflowers for Autophagy Inhibition and Enhanced Antitumor Chemotherapy^†

ZHANG Kaixiang, LIU Junjie, SONG Qiaoli, WANG Danyu, SHI Jinjin, ZHANG Haiyue, LI Jinghong

2020, 41(7):  1461-1469.  doi:10.7503/cjcu20200242

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Autophagy is an important process in eukaryotic cells, in which subcellular membranes undergo dynamic morphological changes, leading to the degradation of cellular proteins and cytoplasmic organelles. High levels of cellular autophagy could protect tumor cells from apoptosis and reduce the antitumor effect of chemotherapy drugs. In this work, we designed a multifunctional DNA nanoflower, which encode DNA aptamer and DNAzyme for targeted drug delivery and gene silencing to inhibit autophagy in tumor cells. Using RT-PCR, we verified that the designed DNA nanoflower can effectively cleave the mRNA of autophagy-related gene(ATG5) in tumor cells. The cytotoxicity and cell apoptosis assay also showed that the synthesized multifunctional DNA nanoflower could enhance antitumor chemotherapy.



Direct Synthesis of SSZ-13 Zeolite Using Tetraethylammonium Hydroxide as an Efficient Organic Template in the Presence of Conventional Aluminum and Silicon Sources^†

LUAN Huimin, CHEN Wei, WU Qinming, XU Hao, HAN Shichao, MENG Xiangju, ZHENG Anmin, XIAO Fengshou

2020, 41(7):  1470-1476.  doi:10.7503/cjcu20200197

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High silica CHA zeolite(SSZ-13) has been commercially applied in selective catalytic reduction of NO_x with ammonia currently, but the use of costly organic templates of N,N,N-trimethyl-adamantammonium hydroxide(TMAdaOH) in the synthesis strongly limits its industrial application. To solve this problem, it is developed a synthetic route using relatively low-cost organic templates such as tetraethylammonium hydroxide(TEAOH), but in this case it is necessary to use costly high silica Y zeolite as a starting source. In this report, we for the first time show that SSZ-13 zeolite could be synthesized directly from conventional silicon and aluminum sources using TEAOH as an efficient organic template by carefully adjusting the starting gels in the presence of SSZ-13 seeds. The obtained aluminosilicate SSZ-13 product has good crystallinity, uniform crystals, and excellent hydrothermal stability. Furthermore, copper-exchanged SSZ-13 zeolite has excellent catalytic performance in NH₃-SCR reaction before and after hydrothermal treatment. The combination of good catalytic performance with low-cost synthesis offers a good opportunity for wide applications of this zeolite in the future.



High-performance Adhesive Material at Dry and Under-seawater Conditions Based on Catechol-functionalized Alternating Copolymer^†

SHA Xinyi, ZHANG Changxu, WANG Yuling, ZHOU Yongfeng

2020, 41(7):  1477-1483.  doi:10.7503/cjcu20200060

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A novel catechol-functionalized alternating copolymer, poly(dopamine-alt-bisphenol A epoxy resin)[P(DA-a-BAER)], was synthesized from the copolymerization between dopamine(DA) and bisphenol A epoxy resin(BAER) monomers via an epoxy-amino click reaction. The resultant alternating copolymer was used as an adhesive material, of which the bonding performances both at dry and under-seawater conditions were investigated with the usage of FeCl₃ as cross-linker. The results showed that P(DA-a-BAER) could achieve excellent bonding strength on various substrates both at dry and under-seawater conditions. Taking stainless steel as an example, a bonding strength of (3.03±0.68) MPa was achieved at atmospheric situation with a 1:3 molar ratio of Fe³⁺ to catechol groups; an under-seawater bonding strength of (0.65±0.10) MPa was achieved when the molar ratio of Fe³⁺ to catechol groups reached 1:6. The crosslinking mechanism of Fe³⁺ was studied by Raman spectrometry and UV-Vis absorption spectrometry, demonstrating that catechol moieties underwent oxidation crosslinking and coordination crosslinking processes. As a result, the cohesion strength of the polymer was enhanced, leading to a high bonding strength.



Fabricating Polysaccharide Micro-hydrogel via Superhydrophobic Pillar-structured Si Substrate ^†

BAO Han, LUO Jing, SHI Lianxin, XU Fujian, WANG Shutao

2020, 41(7):  1484-1491.  doi:10.7503/cjcu20200193

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We have demonstrated a novel method for fabricating polysaccharide micro-hydrogel(PsMH) with uniform sizes. Microdroplets were adhered to micro-pillars and UV-cured during droplets evaporation to fabricate bread-like PsMH with uniform micrometer scale sizes via super-hydrophobic, high-adhesion micro-sized cylindrical structure silicon substrate. Results show that the PsMH with narrow size distributes uniformly on the top of the micro-pillars. The sizes and structure of PsMH can be effectively adjusted via polymer concentration and the diameter of micro-pillars. This polysaccharide-based microgel is expected to be used in drug delivery, nanoparticles carrier and other aspects.



Articles: Inorganic Chemistry

Preparation of Histidine Modified Prussian Blue and Its Interaction with Silver Ions^†

LIU Zhaoyang, SONG Yongxin, WANG Tianshu, SHAN Guiye

2020, 41(7):  1492-1498.  doi:10.7503/cjcu20200089

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The histidine modified Prussian blue(HisPB) was synthesized via hydrothermal method. Scanning electron microscopy(SEM), X-ray diffraction(XRD) and ultraviolet spectrophotometer(UV-Vis) were used to characterize the morphology and structures of the synthesized histidine modified Prussian blue. The volume of histidine modified Prussian blue increased and the surface became smoother. Meanwhile, the functional groups of histidine modified Prussian blue increased. These factors significantly improved the stability of Prussian blue in alkaline solution. The optimal pH value of silver ion detected by HisPB was determined to be 10. Silver ions were detected in a linear range of 6—40 μmol/L by monitoring the changes in absorption peak strength at 800 nm and the changes in color of the solution after the reaction of HisPB with silver ions.



Preparation of Superhydrophobic Porous Silicon and Its Surface Stability^†

MIAO Xiaomei, MAO Keyu, PEI Yongbing, JIANG Jianxiong, YAN Yue, WU Lianbin

2020, 41(7):  1499-1504.  doi:10.7503/cjcu20200079

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The porous silicon has been widely used in many fields due to its great optical properties, but the silicon hydride bonds(Si—H) on the surface of porous silicon were sensitive to the water and oxygen, which will affect the performance of porous silicon. Therefore, it was critically necessary to improve the porous silicon stability by the surface modification. In this article, the surface modification of porous silicon was processed by the hydrosilylation method under the heating conditions. The structure and composition of the functionality porous silicon were characterized and tested by Fourier transform infrared spectroscopy, energy dispersive spectrometer, scanning electron microscopy. The effect of different reaction time on grafting porous silicon was investigated. The results show that the superhydrophobic porous silicon was prepared after 3 h reaction, and it exhibited great stability in the alkaline and air environment.



Analytical Chemistry

Assignment of Polypeptide Disulfide Bonds by Chemical Cleavage and Bio-mass Spectrometry^†

WANG Xiaoyu, YAN Guoquan, ZHOU Xinwen, YANG Pengyuan

2020, 41(7):  1505-1512.  doi:10.7503/cjcu20200262

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Disulfide bridges are important chemical bonds closely related to the structure and function of peptides and proteins. There may be multiple pairs of disulfide bonds when more than two cysteines existed in a peptide. Quickly and accurately assignment is crucial for evaluating the relationship between structure and function of peptide. In this paper, a comprehensive chemical cleavage and mass spectrometry method was developed to assign three pairs of disulfide bonds in Linalotide. Linalotide disulfide bonds were Cys1-Cys6, Cys2-Cys10 and Cys5-Cys13 by mapping tandem mass spectrum of specific peptides. This method provides a new idea for the study of peptide disulfide bond location.



Nitrogen and Sulfur co-Doped Carbon Quantum Dots for Accurate Detection of pH in Gastric Juice^†

HUANG Jialing,LIU Fengjiao,WANG Tingting,LIU Cuie,ZHENG Fengying,WANG Zhenhong,LI Shunxing

2020, 41(7):  1513-1520.  doi:10.7503/cjcu20200133

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Nitrogen-sulfur co-doped carbon quantum dots with blue light, good water solubility, strong stability and high quantum yield(36.23%), were synthesized by one-step hydrothermal method, using salicylic acid and thiourea as raw materials. Under the excitation of 302 nm, there is a good linear relationship between the fluorescence intensity and the pH value in the range of 2.01—5.11 at the emission wavelength of 409 nm, and the correlation coefficient is 0.9931. The change of pH value in gastric juice can be detected in situ and in real time. In view of the fact that the pH value of gastric juice is closely related to the diagnosis of gastric cancer and neonatal monitoring, N,S-CQDs are expected to contribute to the early diagnosis of gastric cancer and neonatal health protection. N,S-CQDs have low cytotoxicity and good biocompatibility. When microcystis aeruginosa cells as phytoplankton model are incubated with 400 μg/mL of N,S-CQDs for 48 h, their survival ratesare 82.8%, indicating that N,S-CQDs could be used as a environmental-friendly fluorescent probe for human gastric cells.



Preparation and Application of Melamine Imprinted Material Using Itaconic Acid as Multidentate Functional Monomer

WANG Xiaoru,ZHANG Na,XING Jun

2020, 41(7):  1521-1530.  doi:10.7503/cjcu20200129

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A molecularly imprinted polymer(MIP) was prepared using melamine(MEL) as template, itaconic acid(IA) as functional monomer and ethylene glycol dimethacrylate(EGDMA) as cross-linker. The effect of molar ratio among these components on the selectivity of MIP was investigated. It is found that the prepared MIP presents the best selectivity to MEL when molar ratio of MEL to IA is 1:1.5. The selectivity coefficient(k) of the synthesized MIP to MEL is 10.41(CYA as control). Since the molar ratio of carboxyl groups(recognition sites) of IA and amino groups(recognizable groups) of MEL is exactly 1: 1, the non-specific adsorption caused by excessive functional monomers will be avoided. Scatchard analysis indicates that MIP only exhibits specific binding to MEL within the concentration range from 1 to 100 mg/L of MEL. On the other hand, when CYR is used as the control, the k_NIP is less than 1 but the k_MIP is greater than 1. This result implies the synthesized MIP has good discriminating ability for the shape of molecules. Using the prepared MIP as the adsorbent of solid phase extraction(SPE), a method of MISPE hyphenated to high performance liquid chromatography with UV detector(MISPE-HPLC/UV) was established for determination of melamine. The recoveries of MEL in the spiked milk and milk powder samples vary from 92.34% to 109.4%.



Carbon Dots Based-on Polyethyleneimines as a Ratiometric Fluorescent Sensor of Morin^†

XUE Yarong, LI Hongwei, WU Yuqing

2020, 41(7):  1531-1536.  doi:10.7503/cjcu20200018

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A blue-emitting carbon dots(CDs) based on polyethyleneimines(PEI) was prepared by hydrothermal synthesis method, which is applied to detect morin with a ratiometric fluorescence response. The detection method has very fast response speed, high selectivity and sensitivity, and strong anti-interference. The fluorescence emission of CDs is quenched and a new emission peak centered at 555 nm appears and enhances gradually in the presence of morin. The fluorescence intensity ratio of the new emission peak(555 nm) to the original emission peak(460 nm) increases linearly in the range from 1.0×10^-6 to 4.0×10^-5 mol/L. In particular, the ratio response is very sensitive with an extremely low detection limit of 3.0×10^-8 mol/L. The proposed probe shows no response to other commercial available flavonol with similar structure, common metal ions and amino acids, which indicates a high selectivity toward morin. In addition, the fluorescent color was changed from blue to yellow in the presence of morin, which displays a visual detection method. And the CDs can be applied to detect morin in diluted fetal calf serum either. Therefore, the present study supplies a cost-effective, fast and easily performed approach to detect morin with high selectivity and sensitivity.



Organic Chemistry

Crystal Structure Analysis and Properties of Bis(dialkyl-5-aminotetrazolium) Dodecahydrododecanoates^†

MENG Lingchao,SHENG Lili,SHAN Zixing,YANG Rongjie,ZHOU Zhiming

2020, 41(7):  1537-1543.  doi:10.7503/cjcu20200115

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Eleven kinds of bis(dialkyl-5-aminotetrazolium) dodecadodecaborates were prepared, their crystal structures were characterized by X-ray single crystal diffractometer. The detonation properties of the compounds were calculated using EXPLO5 software. The results showed that the densities of eleven compounds were between 1.097—1.229 g/cm³. The spatial crystal forms were mainly affected by the position of the substituents. The crystal structures belonged two types, which were triclinic and monoclinic. The unit cell size was related to the number of molecules in cell, the number of carbon atoms in the cation-substituted alkyl group had no significant effect on the length of the C—N connected to the tetrazole. For compounds with the same substitution position, the heat of formation and explosion heat decrease with the increase of the number of carbon atoms in the alkye substituent.



High Selectivity of Enol-keto Tautomers Imine Derivative for the Recognition of Co^2+†

CAO Cheng,CAO Tian,YAN Penji,WANG Qingyun,YUE Guoren,JI Xiangdong

2020, 41(7):  1544-1551.  doi:10.7503/cjcu20200085

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A new enol-keto tautomers imine derivative R was designed and synthesized. The recognition property of the receptor R for 18 kinds of cations was studied by ultraviolet absorption spectroscopy(UV-Vis) analysis and naked-eye detection. The results showed that the receptor R had significant recognition ability for Co²⁺, Fe²⁺ and Ni²⁺ through UV-Vis analysis, which found single colorimetric recognition of Co²⁺ by color changes. The Job’s plot indicated that the formation of complex between receptor R and Co²⁺ was in 1:1 stoichiometric ratios, and the limit of lowest detection of receptor R for Co²⁺ was 4.14×10^-7 mol/L. Meanwhile, naked recognition paper of receptor R was prepared. The enol-keto tautomerism of receptor R was illustrated during recognition process through theoretical calculation and nuclear magnetic resonance titration.



Preparation and Application of Specificity Phosphohistidine Antibody^†

LI Rongqing,LIU Jialu,FAN Ruochen,BAI Pengyang,ZHANG Liying,QUAN Chunshan

2020, 41(7):  1552-1558.  doi:10.7503/cjcu20200078

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A novel phosphorylated histidine analogue was synthesized using 4-iodopyrazole and diethyl phosphite as raw materials and characterized by nuclear magnetic resonance spectroscopy(NMR). It was used as hapten to prepare phosphohistidine antibody(Anti-pHis). Enzyme-linked immunosorbent assay, dot blot and western blot methods were used to detect the specificity and sensitivity of the Anti-pHis. The results showed that the Anti-pHis had excellent avidity and sensitivity for histidine phosphorylated protein, and the Anti-pHis was successfully applied to the detection of histidine phosphorylated protein in the lysate of microbial cells.



High Efficient and Green Approach to the Synthesis of Leuprolide in Continuous-flow Microreactor^†

LI Shijie,YANG Yang,CUI Yingying,SU Xianbin

2020, 41(7):  1559-1566.  doi:10.7503/cjcu20200032

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A high efficient and green approach was repored for the synthesis of leuprorelin which is a nonapeptide analogue of gonadotrophin releasing hormone(GnRH) used to treat a wide range of sex hormone-related disorders-based on a continuous-flow system. Benzyloxycarbonyl(Cbz)-protected amino acids were used in this approach and coupling reaction was carried out in micro-channel reactors efficiently followed by extraction to remove impurities. A rapid and clean deprotection of Cbz then successfully achieved through hydrogenolysis via a column packed with Pd/C catalyst. This approach enabled the stiochiometric amidation of peptide chain elongation and catalytic deprotection hence the consumption of raw materials were dramatically reduced. This new strategy will find more application in peptide manufacturing.



Oxidative Trifluoromethylation of CF₃SO₂Na with Olefins Mediated by Diacetyl^†

XU Wenyi,FENG Yisi

2020, 41(7):  1567-1574.  doi:10.7503/cjcu20190665

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α-Trifluoromethyl ketones have been identified as versatile building blocks for the synthesis of various trifluoromethyl-functionalized molecules. Although there are significant advantages in the development of methods toward direct transformations of styrenes into α-trifluoromethyl ketones, most procedures leading to α-trifluoromethyl ketones require heavy- or transition-metal-based complexes. Herein, a new method was developed for the synthesis of α-trifluoromethyl ketones via diacetyl-catalyzed photooxidative keto-trifluoromethylation of styrenes with sodium trifluorometnanesulfinate(CF₃SO₂Na) under an air atmosphere. Twenty-two α-ketone trifluoromethyl compounds were synthesized in the yields ranging from 52% to 78%. And their structures were characterized by nuclear magnetic resonance spectroscopy(NMR) and gas chromatography-mass spectrometry(GC-MS) analysis. This reaction employed the commercially available, low cost, and easy to handle langloisreagent(CF₃SO₂Na) as a CF₃-radical source, and diacetyl was used as promising low-cost radical initiators to generate CF₃ radicals from sodium trifluorometnanesulfinate efficiently. And the reaction proceeded smoothly to give the products in moderate yield with mild conditions, a simple system and good functional group tolerance. Furthermore, mechanism investigation indicated that the oxidant H₂O₂ played an important role in promoting the photocatalytic cycle process. This photochemical strategy employed diacetyl, instead of expensive metal catalysis, proved to be a greener route to synthesize α-trifluoromethyl ketones compounds.



Physical Chemistry

Preparation of Ni₂P/N, S co-Doped Reduced Graphene Oxide Composites and Their Electrocatalytic Properties for Hydrogen Evolution^†

ZHAO Guoqing, YUAN Zhao, WANG Lian, GUO Zhuo

2020, 41(7):  1575-1581.  doi:10.7503/cjcu20200161

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Developing new type of electrolyzed water catalysts is very important. In this work, nickel phosphide nanocrystals supported on N, S co-doped reduced graphene oxide(Ni₂P/NSRGO) as a high activity catalyst was synthesized by the simple hydrothermal process. The graphene can anchor nickel phosphide and improve catalytic performance. The results of electrochemical test showed that the Ni₂P/NSRGO composite electrocatalyst showed better hydrogen evolution performance than Ni₂P/NRGO and Ni₂P/RGO catalysts, indicating the addition of N and S has a positive effect on the improvement of hydrogen evolution performance. The Ni₂P/NSRGO nanocrystals catalyst shows excellent performance with a small Tafel slope of 35 mV/dec, longterm durability and a low overpotential(η₁₀=140 mV) in 0.5 mol/L H₂SO₄ for the hydrogen evolution reaction(HER).



Fiber Supported Carbon Black Metal Phthalocyanine Axial Complex to Mimic Enzyme for Highly Efficient Catalytic Degradation of Organic Pollutant in Water^†

XIA Yun, Lü Wangyang, CHEN Wenxing, LI Nan

2020, 41(7):  1582-1590.  doi:10.7503/cjcu20200143

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Natural heme catalase has high selective catalysis, but it is easy to deactivate. The enzyme-like catalyst carbon black iron hexadecachlorophthalocyanine axial complex(FePcCl₁₆-Py-CB)was synthesized for improving the activity and stability of enzyme. In the catalyst, FePcCl₁₆ with stable performance worked as active site, tetraminopyridine was introduced as ligand, carbon back was employed as carrier. Fiber-supported enzyme mimicking catalyst FePcCl₁₆-Py-CB@LMPET which was easy to separate with water was prepared by FePcCl₁₆-Py-CB loaded on low melting point sheath-core polyester fibers(LMPET) via thermal bonding. The enzyme-like catalytic system was designed based on FePcCl₁₆-Py-CB@LMPET as catalyst, H₂O₂ as oxidant, DXMS as substrate to investigate the catalytic activity and the recycle performance, to explore the catalytic mechanism and the degradation process of DXMS. The results showed that high valent iron oxo[Fe(Ⅳ)=O] produced by heterolytic cleavage of H₂O₂ was the main active species, thus the system exhibited excellent catalytic activity and stable performance under mild condition. The final degradation products of the catalytic system were all small molecular acids within 120 min. The construction of the enzyme-like catalytic system provides a new idea for wastewater treatment.



Construction of HRP Immobilized Enzyme Reactor Based on Hierarchically Porous Metal-organic Framework and Its Dye Degradation Application^†

GAO Xia,PAN Huibin,QIAO Chengfang,CHEN Fengying,ZHOU Yuan,YANG Wenhua

2020, 41(7):  1591-1599.  doi:10.7503/cjcu20200130

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Using the unstable Cu-MOF as template agent, the hierarchically porous Zr-MOF was prepared by a self-assembled template method. Horseradish peroxidase(HRP) was successfully immobilized into the hierarchically porous Zr-MOF via physical adsorption. The effect of pore size on catalytic activity of immobilized enzyme reactor was studied by changing the concentration of the pore size regulator benzoic acid(HBC). The effects of pH value of buffer solution, immobilized time and temperature on immobilized effect were investigated. The HRP-catalyzed degradation of crystal violet was used as a model reaction to study the operational stability and reusability of HRP@Zr-MOF. The results showed that the optimal conditions are the buffer pH=3.0, the immobilization time of 60 min and the temperature of 30 ℃, and the maximum immobilization was 61.6 mg/g. HRP@Zr-MOF showed better operational stability than the free enzyme. After 10 cycles, HRP@Zr-MOF can still remain 62.3% of the catalytic activity. When HRP@Zr-MOF was applied to the degradation of crystal violet in real water samples, they show very high catalytic efficiency with the degradation rate of more than 90% within 5 min.



Preparation and Characterization of Pd-Cu/hydroxyapatite Catalyst and Its Catalytic Performance for Room-temperature CO Oxidation in Humid Circumstances^†

LI Xiao,XING Lisha,ZHAO Wanjun,WANG Yongzhao,ZHAO Yongxiang

2020, 41(7):  1600-1608.  doi:10.7503/cjcu20200127

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Hydroxyapatite supports(HAP-SG, HAP-HT) were prepared by sol-gel and hydrothermal methods, respectively. Pd-Cu/HAP catalysts(PC-SG, PC-HT) were synthesized by an impregnation method, and the catalytic activities toward CO oxidation at room temperature and in humid circumstances were investigated. The Pd-Cu/HAP catalysts were characterized by inductively coupled plasma optical emission spectrometry(ICP-OES), N₂-physisorption, X-ray diffraction(XRD), Fourier transform infrared(FTIR), H₂ temperature programmed reduction(H₂-TPR), CO₂ temperature programmed desorption(CO₂-TPD), X-ray photoelectron spectroscopy(XPS)and CO in-situ diffuse reflection using Fourier transform spectroscopy(DRIFTS). The results show that compared with PC-SG, PC-HT possesses the larger specific surface area and pore volume, contains more Cu₂Cl(OH)₃ species with stronger interactions with Pd species and support; more importantly, Pd⁺ species with stronger CO activation ability and more Cu⁺ species with stronger redox property, as well as fewer and weaker basic sites present in PC-HT, thus PC-HT exhibits more excellent CO catalytic oxidation performance for room-temperature CO oxidation in humid circumstances.



Quinone-based Covalent Organic Frameworks for Efficient Oxygen Evolution Reaction^†

CHANG Jianhong, XU Guojie, LI Hui, FANG Qianrong

2020, 41(7):  1609-1614.  doi:10.7503/cjcu2020112

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Covalent organic frameworks(COFs) are a new kind of crystalline organic porous polymers with high specific surface area, regular structure and designability, which has been applied in many domains. However, functionalized covalent organic frameworks still need to be further explored. Herein, a quinone-based COF(2,6-diaminoanthraquinone-COF, DAAQ-COF) was synthesized by using anthraquinone as building blocks, and characterized by powder X-ray diffraction(PXRD), nitrogen adsorption-desorption analysis, Fourier transform infrared(FTIR) spectrometry and thermogravimetry analysis(TGA) etc. It is showed that the synthesized DAAQ-COF has high crystallinity and specific surface area(577 m²/g). Furthermore, quinone-functionalized metal-free DAAQ-COF exhibits effective oxygen evolution reduction(OER), with a overpotential of 389 mV at 10 mA/cm² and a Tafel slope of 135 mV/dec. The introduced quinone group effectively changes the electronic structure and chemical properties of the COF framework, as well as the high crystallinity and specific surface area of the COF material itself, which allows the reactant more efficiently accessible to the active sites for better OER performance. These results show that the rational design of functionalized COFs can promote the development of their broader application prospects in OER.



Construction and Photocatalytic Performance of Quantum Dots Self-decorated TiO₂ p-n Homojunction^†

WANG Feifan, WANG Songbo, YAO Keyi, ZHANG Lei, DU Wei, CHENG Penggao, ZHANG Jianping, TANG Na

2020, 41(7):  1615-1624.  doi:10.7503/cjcu20200107

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Quantum dots(QDs) self-decorated TiO₂ p-n homojunction(PNT-x) samples were fabricated by in-situ depositing p-type TiO₂ QDs on the surface of n-type TiO₂ nanosheets. The composition and structure of the samples were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), photoluminescence spectrometry(PL), Raman spectrometry, UV visible diffuse reflectance spectrometry(UV-Vis DRS), photoelectrochemical test and electrochemical impedance spectroscopy(EIS) analyses. The results indicate that PNT-x exhibits TiO₂ QDs self-decorated structure. Meanwhile, there exist metal and oxygen vacancies in QDs and nanosheets, respectively, and the content of vacancies can be modulated by the composition. Therefore, the as-prepared PNT-x show typical characteristics of p-n homojunction, and the difference of Fermi level and internal electrical field is stronger than that in n-n type Ⅱ homojunction and bulk p-n homojunction, thus leading to a significantly high charge separation and transfer efficiency. Under illumination, the order of photocatalytic activity is PNT-400>p-25>PNT-600>PNT-200>p-TiO₂>n-TiO₂, and PNT-400 display the photocatalytic hydrogen evolution rate as high as 41.7 mmol·g^-1·h^-1, which is 4.3, 3.6 and 2.3 times that of n-TiO₂ nanosheets, type Ⅱ homojunction and bulk p-n homojunction, respectively, as well as a good catalytic stability.



Planar Tetracoordinate Boron and Pentacoordinate Boron in B₆S₅ Clusters^†

WANG Yiqiao,WANG Cong,LIU Xingman,ZHANG Min,GENG Yun,ZHAO Liang

2020, 41(7):  1625-1630.  doi:10.7503/cjcu20200106

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At the level of B3LYP/def2-TZVP optimization and CCSD single point energy, $B_{6}S^{n}_{5}$ (n=0, +1, +2) was utilized to validate the valuable effect of peripheral sulfur atom on constructing planar coordinated boron. The structures of global energy minimum(GEM) and the second lowest energy minimum in three charge states are purely planar ones, and their structures are very similar. Only their order is exchanged with the loss of the electrons. There exists a planar pentacoordinate boron in the GEM structure of D_5h-B₆S₅ due to the 18 electron rule, and there are all the planar tetracoordinate borons in the GEM structure of $B_{6}S^{n}_{5}$ (n=0, +1, +2). Meanwhile, the sulfur-bridging bonding is another key factor to maintain their planar molecular structures.



Synergism Between Asphaltene and Its Subfractions and Alkylbenzene Sulfonate Solutions in Lowering Dynamic Interfacial Tensions^†

JIA Xuemei, CHENG Tiexin, ZHOU Guangdong

2020, 41(7):  1631-1637.  doi:10.7503/cjcu20200099

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Asphaltene extracted from Daqing crude oil was separated into four subfractions by precipitation method of mixed solvents. The dynamic interfacial tensions(DIFTs) of alkylbenzene sulfonate(p-S14-4) aqueous solutions against model oil containing asphaltene and its subfractions were measured. The results revealed that the molecular size, concentration and polarity of asphaltene and its subfractions had a significant effect on DIFTs. For asphaltene subfractions with larger molecular size, DIFTs curves presented the "L" shape and minimum interfacial tension(IFT_min) had a slight variation with the concentration and polarity, because the formation of mixed adsorption films between them and p-S14-4 molecules was difficult. For asphaltene and its subfractions with smaller molecular size, at high concentrations, these subfractions quickly diffused to the interface to form a tightly mixed adsorption film with p-S14-4 molecules, which can instantly lower the interfacial tension(IFT); with time going on, the molecules at the interface layer rearranged. As a result, the DIFTs curves presented "V" shape. Moreover, in this case, asphaltene and its subfractions with higher polarity resulted in lower IFT_min because of the more obvious synergism.



Fractal, Plasmonic Black Gold for Hot Electron Catalysis^†

YU Renpeng, HAN Mei, ZHANG Mengyao, LIU Jianfang, LI Moxia, HU Jiawen

2020, 41(7):  1638-1644.  doi:10.7503/cjcu20200092

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This study takes the advantage of the overcurrent “burning” phenomenon in electroplating industry to prepare plasmonic black gold using one-step overcurrent electrodeposition. The characterization results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and ultraviolet-visible-near infrared absorption spectroscopy reveal that the black gold shows a three-dimensional fractal nanostructure composed of polycrystalline gold, which can absorb light over a broad-band range of 400—1800 nm. The results of methanol electrocatalytic oxidation show that the overall electrocatalytic efficiency of the black gold can be enhanced by 15.2% under light illumination from a Xe lamp, suggesting good hot electron catalytic activity. The improvement of the catalytic performance is mainly contributed to the plasmon-generated hot electrons, with minor contribution from the increased temperature. Under monochromatic light illumination with different wavelengthes, the black Au shows no obvious variation in the catalytic efficiency, suggesting its light utilization capability has no apparent dependence on the wavelength of the illumination light.



Preparation of Boron and Iodine co-Doped Carbon Nitride and Its Performance in Photocatalytic Hydrogen Evolution from Water^†

ZHU Yuxin, OUYANG Jie, SONG Yanhua, TANG Sheng, CUI Yanjuan

2020, 41(7):  1645-1652.  doi:10.7503/cjcu20200084

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Boron and iodine co-doped carbon nitride(CNBI) catalysts were synthesized using boron oxide as the boron source, ammonium iodide as the iodine source and melamine as the raw-material by one-step calcination method. The samples were characterized and analyzed using X-ray powder diffractometer(XRD), transmission electron microscope(TEM), Fourier transform infrared spectrometer(FTIR), X-ray photoelectron spectrometer(XPS), ultraviolet-visible(UV-Vis) spectrophotometer and electrochemical workstation. The performance of the catalysts was tested by hydrogen production from water under visible light irradiation. The results indicated that the B and I elements were uniformly dispersed and doped into the CN conjugate skeleton to form B, I co-doped CNBI semiconductor materials. Compared with undoped CN, the band gap of co-doped catalysts was slightly reduced, the light absorption range was expanded. The separation efficiency of photo-generated electron-hole pairs was improved, mainly due to the difference in electronegativity of the B and I elements, which helps redispersed the photo-generated carriers of CN. The CNBI(0.1,0.3) sample had the best photocatalytic hydrogen production performance, and hydrogen production rate was 104.30 μmol/h under visible light irradiation, which is 4.6 times that of pure CN(22.74 μmol/h), 2.0 times of CNB(0.1)(51.92 μmol/h) and 3.1 times of CNI(0.3)(33.37 μmol/h), respectively.



Theoretical Studies of Triphenyl-s-triazine Groups Regulating Photoelectric Properties of Sensitizing Dyes^†

WANG Linshuo, LI Kunjie, LIU Yumin, ZHAO Ruihong, LI Qing, QIAN Xin, ZHANG Fan, XUE Zhiwei

2020, 41(7):  1653-1660.  doi:10.7503/cjcu20200077

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By adding the 2,4,6-triphenyl-s-triazine group into the donor-acceptor-π-acceptor(D-A-π-A) configuration sensitizer, seven kinds of new sensitizers were designed. Then the methods of density functional theory(DFT) and time-dependent density functional theory(TD-DFT) were used to study the geometric con-figuration, front-line orbital energy levels, absorption spectral, excitation energy, intramolecular charge transport and other related properties. The results indicate that the 2,4,6-triphenyl-s-triazine group can effectively improve the performance of dyes, which using triphenylamine as electron donors. The dye HBL2, which attaching triphenylamine to both sides of 2,4,6-triphenyl-s-triazine, has lower band gap and higher light harvesting efficiency(LHE). The electron transfer results of the dye HBL2 analysed by the Multiwfn show that 2,4,6-triphenyl-s-triazine not only acts as electronic push-pull effect, but also acts as a donor under certain conditions. So it can promote the intramolecular charge transfer.



Application of Porous Black Titanium Dioxide with Oxygen Vacancy/Polyethylene as a Composite Separator for Lithium Sulfur Batteries^†

WU Tong, CONG Lina, SUN Liqun, XIE Haiming

2020, 41(7):  1661-1669.  doi:10.7503/cjcu20200057

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In this work, a mesoporous black titanium dioxide(b-TiO₂) with highly ordered oxygen vacancy was synthesized by two-step solution method and coated on the surface of polyethylene separator to obtain the composite separator for lithium-sulfur(Li-S) battery. The electrochemical performance of the Li-S battery with this composite separator was studied. The results show that the mesoporous b-TiO₂ presents a good conductivity due to oxygen vacancy, and can enhance the physical and chemical adsorption of polysulfide, thus the obtained Li-S batteries possess excellent discharge specific capacities(1257 mA·h/g at 0.1C) and outstan-ding cycling performance(discharge specific capacity 821 mA·h/g after 100 cycles).



An Effective Method of Reducing the Internal Reorganization Energy Based on Windmill-like Grid Composed of Four Carbazoles^†

SHI Haihan,WU Xiangping,PENG Xinzhe,YU Guojing,DONG Chaoyang,JI Yaoyao,YANG Siwen,CHEN Junlin,WANG Jin,RAN Xueqin,YANG Lei,XIE Linghai,HUANG Wei

2020, 41(7):  1670-1676.  doi:10.7503/cjcu20200054

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The charge mobility of organic semiconductor materials has been a research hotspot. A new type of grid-like organic semiconductor material was designed and calculated through density functional theory(DFT). The structures of windmill-like grid composed of four carbazoles(GZP) were discussed in detail, as well as their thermodynamic and electronic properties. The results show that they have such a regular structure that may be easily synthesized in the laboratory. The boat-like GZP1(0 kJ/mol) is more stable than the ship-type GZP2(122.88 kJ/mol). The internal and external diameters of GZP1 are 0.298 and 1.079 nm, respectively. Especially, the internal recombination energy of GZP1 is very low, so that it can be used as a good charge transport material.



Preparation of Zn₂In₂S₅ Photocatalyst by Post-treatment with Hydrochloric Acid for Effective Photocatalytic Hydrogen Evolution^†

PENG Shaoqin, LI Ziqin, HUANG Mingtao, LI Yuexiang

2020, 41(7):  1677-1683.  doi:10.7503/cjcu20200023

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ZnIn₂S₄ solid solutions were prepared by hydrothermal method and a series of Zn_mIn₂S_m+3(m=1—5, integer) solid solutions were obtained by post-treatment of ZnIn₂S₄ with HCl. The composition, structure and performance of the catalysts were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), UV-Visible diffuse reflective spectroscopy(UV-Vis DRS), photoluminescence(PL) spectroscopy and electrochemical tests. The visible light photocatalytic hydrogen production activity of a series of solid solutions was studied. It is found that ZnIn₂S₄ solid solution can be converted into Zn₂In₂S₅ solid solution after treatment with 0.5 mol/L HCl, and its hydrogen production activity is the highest, which is 2.2 times that of ZnIn₂S₄ solid solution. The catalyst also has good stability.



Material Chemistry

Synthesis of Li-rich Layers/Spinel/Carbon Composite Cathode Materials with Phenol Formaldehyde Resin and Its Electrochemical Performance^†

LU Di,ZHENG Chunman,CHEN Yufang,LI Yujie,ZHANG Hongmei

2020, 41(7):  1684-1690.  doi:10.7503/cjcu20200033

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A li-rich layers/spinel/carbon heterostructure cathode material was synthesized by phenol formaldehyde resin coating and subsequent carbon thermal reaction, the structure, monography and electrochemical performance of the material were studied. For this structure, the spinel phase plays a role to provide a three-dimensional lithium-ion transport channel while the carbon coating layer help with the conductivity of the cathode. Those two layers lower the electrochemical impedance of the material and improve the specific capacity. The cathode material deliver an excellent performance of 135.1 mA·h/g at 5C.