Table of Content

10 October 2023, Volume 44 Issue 10

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Content

Cover and Content of Chemical Journal of Chinese Universities Vol.44 No.10(2023)

2023, 44(10):  1-6. 

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Perspective

Recent Breakthrough Progresses in the Fundamental Research of Zeolites in China

QI Ganggang, MENG Xiangju

2023, 44(10):  20230227.  doi:10.7503/cjcu20230227

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Zeolites have been widely used in ion-exchange， sorption and separation as well as catalysis fields due to their large surface area， high adsorption capacity， uniform and intricate channels， high thermal and hydrothermal stabilities， and well-defined micropores with excellent shape-selectivity in catalysis. In recent years， a series of breakthrough achievements has been made in the fundamental research of zeolites in China. This manuscript will briefly summarize these progresses including the accelerated crystallization of zeolites via hydroxyl free radicals， construction of stable aluminosilicate zeolite with extra-large pores， in-situ imaging of topological flexibility of a rigid zeolite framework as well as atomic imaging of zeolite-confined single molecules by electron microscopy， excellent performance in adsorption-separation and catalytic transformation of small hydrocarbon molecules， and flexible zeolite electrolyte solid-state Li-air battery. Prospective and challenges in the fundamental research of zeolites will also be conveyed.



Review

Structure and Photoluminescence Origin of Carbon Dots

TAO Songyuan, XIA Chunlei, YANG Bai

2023, 44(10):  20230241.  doi:10.7503/cjcu20230241

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As environmentally friendly and high-performance nanomaterials， carbon dots（CDs） have shown good application potential in many cutting-edge fields， e.g. optoelectronic devices， biological diagnosis and treatment， and energy catalysis， which has attracted much attention in recent years. Due to the significant differences in raw materials and synthesis methods， CDs always show complex optical properties. Based on the previous research work of our research group and the analysis of the particle growth process， this article introduces the main photoluminescence（PL） mechanisms of CDs， including the carbon core state of conjugated π-domain， surface-edge state， organic fluorophores-like molecular state， and crosslink enhanced emission effect. This paper comprehensively reviewed controversial scientific issues on particle structure and PL origin in the field of CDs， and prospected the future trends.



Progress in the Construction of Metal Oxide Heterojunctions and Their Application in Photocatalytic CO₂ Reduction

LI Mengdie, WANG Zumin, QI Jian, YU Ranbo

2023, 44(10):  20230196.  doi:10.7503/cjcu20230196

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China has put forward the strategic goals of “carbon emissions peak” in 2030 and “carbon neutrality” in 2060. It is of great significance to convert CO₂ into high-value-added chemical products and liquid fuels， which can reduce the dependence on coal， oil and other traditional resources while achieving carbon emission reduction. Photocatalytic CO₂ reduction is a very important way， and the design and preparation of efficient photocatalysts for CO₂ reduction are the key. Well-defined heterojunction structures between metals and semiconductors or semi- conductors with matching electronic band structures can effectively promote charge transfer and inhibit the recombination of photogenerated electrons and holes， thus improving the photocatalytic performance. This review focuses on the recent progress of oxide-based heterostructures for photocatalytic CO₂ reduction， and systematically summarizes the types and components of the formation of heterostructures， and expounds the internal mechanism of improving the performance of CO₂ photocatalysis. Furthermore， the direction of research in this field is also prospected.



Split Intein： a Versatile Tool for Traceless Peptide Segment Ligation

HAN Dongyang, REN Yuxiang, YANG Ziyi, HUANG He, ZHENG Jishen

2023, 44(10):  20230188.  doi:10.7503/cjcu20230188

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Split intein can efficiently ligate peptide segments via a splicing reaction in a traceless manner and therefore has attracted great attention. Based on the structural characteristics and splicing reaction process of split intein， this paper comprehensively reviewed the recent progresses on the performance optimization and expanded applications of split intein， and revealed its great potential in the field of chemical protein synthesis as an increasingly sophisticated protein engineering technology. Finally， the challenges presented in the split intein- mediated protein trans-splicing and potential solutions in the future research were briefly discussed.



Development of Nucleic Acid-mediated Nanomaterials and Their Applications

HAO Qiangjun, YE Zi, WEN Bei, PENG Hanyong

2023, 44(10):  20230125.  doi:10.7503/cjcu20230125

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Nucleic acid is a powerful building block for functional nanomaterials with extensive physiological function and structural potential. It’s an ideal template to mediate the growth of metal nanoparticles， precisely controlling their size， structure and morphology. In this review， we introduced the mechanism of interaction between nucleic acid and metal ions， and reviewed the methods for synthesizing nanomaterials using the nucleic acid templates. The unique properties of nucleic acid mediated nanoparticles enable their broad application in molecule diagnosis， cell imaging， catalytic degradation， drug delivery and therapy. It provides a new strategy to improve the design and construction of functional nanomaterials and explore their application.



Articles: Inorganic Chemistry

High-performance Two-dimensional Tungsten Diselenide-based Photodetector

LIU Xiangyu, TANG Jiaqi, TAN Zhifu, PAN Caofeng

2023, 44(10):  20230217.  doi:10.7503/cjcu20230217

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Two-dimensional transition-metal dichalcogenides（TMDs） have gained widespread attention in the research field of nano-photodetectors. In this work， two-dimensional tungsten diselenide（WSe₂） materials were prepared by physical vapor deposition（PVD）. Different conductivity types and better electrical properties were demonstrated by comparison with materials prepared by chemical vapor deposition（CVD） methods. Meanwhile， a pn junction device composed of the same WSe₂ material was prepared by using the properties of p-type and n-type conductivity of the materials obtained by two different processes. The test has proved that the device has unidirectional rectification under dark conditions and extremely sensitive response to light， which proves that WSe₂ has broad development prospects in the field of optoelectronic device applications.



High-performance Electro-optical Dual-control Color-changing Devices Based on WO₃/Ag and TiO₂/NiO/CdS Composite Electrodes

LIU Chunlei, YANG Jikai, LIU Yulin, LI Siyuan, LIU Haorui

2023, 44(10):  20230203.  doi:10.7503/cjcu20230203

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Electrochromic technology has been widely used in the field of smart windows， but the electrochromic process still needs to be completed by applying an external voltage. The electro-optical dual-control color-changing device constructed by combining electrochromic devices with solar cells does not require external power supply to achieve smart color-changing control. The color-changing cathode and photoanode with excellent performance are very important for electro-optical dual-control color-changing devices. WO₃/Ag composite films were prepared by hydrothermal method combined with electrodeposition method and their electrochromic properties were studied. TiO₂/NiO/CdS composite films were prepared by hydrothermal method， electrodeposition method combined with continuous ion layer deposition method and their photoelectric conversion properties were studied. Finally， WO₃/Ag composite films and TiO₂/NiO/CdS composite films were used as color-changing cathode and photoanode， respectively， to construct electro-optical dual-control WO₃/Ag-CdS/NiO/TiO₂ color-changing devices. The WO₃/Ag-CdS/NiO/TiO₂ electro-optical dual-control color-changing device has a relatively fast optical-control response time（82.4 s/135.6 s for coloring/bleaching） and a good optical modulation range（30.4% at 630 nm）. It has a wide application prospect as a color-changing smart window in the fields of construction and automobile.



Rapid Synthesis of SSZ-13 Zeolite via Interzeolite Transformation of L Zeolite and Formation Mechanism of Its Hollow Structure

ZHANG Zongyang, LI Yuping, ZHANG Ruoxi, LIU Yufeng, CHEN Ze, HAN Lina, HAN Peide

2023, 44(10):  20230034.  doi:10.7503/cjcu20230034

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Using N，N，N-trimethyl-1-amantamine hydroxide（TMAdaOH） as organic structure directing agents， SSZ-13 zeolite was synthesized by direct conversion of zeolite L with a low SiO₂/Al₂O₃ ratio（SAR） by adding additional Si source at 180 ℃. The crystallization process was tracked by XRD， FTIR， SEM， N₂ adsorption-desorption and HRTEM characterization. It was found that the crystallization rate was greatly accelerated at 180 ℃， and highly crystalline SSZ-13 was synthesized after 4.5 h of crystallization. At the same time， it was noted that hollow crystals appeared during the crystallization process under this experimental condition. The formation mechanism of the hollowing structure was further explored by combining with SEM-EDS characterization. It was found that during the process of slow degradation of zeolite L and the simultaneous rapid nucleation and growth of SSZ-13， the SAR in the middle of zeolite crystals was higher than that at the edge， that is， the SAR distribution in the whole crystal was uneven. Silicon-rich crystal nucleus can be selectively desilicated under alkaline conditions， leading to the hollow phenomenon. Finally， the catalytic performance of the hollow samples after copper ion exchange in NH₃ selective catalytic reduction（NH₃-SCR） reaction of NO _x was investigated， and the catalytic results were analyzed in combination with the characterization of NH₃ temperature-programmed desorption（NH₃-TPD） and H₂ temperature-programmed reduction（H₂-TPR）.



Controlled Growth of Silver Nanowires with Chemically Exfoliated Ti₃C₂T _x Nanosheets

LIU Jianfang, ZHAO Haocheng, LIANG Fangnan, YOU Xuerui, ZHOU Kun

2023, 44(10):  20230009.  doi:10.7503/cjcu20230009

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Silver nanowires（Ag NWs） are important materials for next-generation transparent conductors（TCs）. However， Ag NWs synthesized by polyol reduction have large diameters， which affects the optical and electrical properties of Ag NWs thin films. Herein， we propose a new method for the synthesis of Ag NWs using MXene， and the growth of Ag NWs with different diameters can be achieved by controlling the size of nanosheets. The growth mechanism was studied by high-resolution transmission electron microscopy（HRTEM）， revealing the important role of MXene as both a reducing and nucleating agent. Therefore， our work exhibits that as a novel two-dimensional layered material， MXene is helpful for the synthesis of high-quality Ag NWs， making them a new-generation material for high-performance flexible transparent electrode.



Organic Chemistry

Enhancement of Solubility， Stability and Permeation of Skin-care Ingredients by Amphiphilic Sulfonated Calix［8］arene

YU Hongmei, LI Shihui, TIAN Hanwen, LIN Yilin, ZHANG Shuxin, GENG Wenchao, LI Huabin, WANG Honglei, LIU Juan, GUO Dongsheng

2023, 44(10):  20230143.  doi:10.7503/cjcu20230143

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The sulfonated calix［8］arene modified with dodecyl at the lower-rim（SC8A-12C） was synthesized to improve the solubility and stability of vitamin A（Va） in aqueous solution， and promote the percutaneous permeability of Va. Lipophilic Va is almost insoluble in water， SC8A-12C could improve solubility of Va to 1.1 mg/mL and prolong the half-life of Va in aqueous solution from 5 h to 35 h. In vitro transdermal test showed that SC8A-12C increased the transdermal amount of Va by 16.9 times. SC8A-12C also increased the solubility of various skin-care ingredients， such as phenoethylresorcinol， salicylic acid， quercetin and azelaic acid， and increased the transdermal amount of salicylic acid by 3.8 times. SC8A-12C improved the efficacy of Va through improving solubility， stability and skin permeability， and was expected to develop oil-free skin-care products of Va. In view of the SC8A-12C improving solubility of a variety of skin-care ingredients， it is expected to contribute to the development of multi-functional skin-care products.



Effects of Cucurbit［n］uril Hosts on Mechanochromic Properties of Divinylanthracene Derivatives

LI Zhuo, SUN Dongdong, HAN Xie, LIU Simin

2023, 44(10):  20230171.  doi:10.7503/cjcu20230171

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Three 9，10-divinylanthracene derivatives（G1—G3） were designed and synthesized in this work. The host-guest complexation of those derivatives with cucurbit［n］urils（CB［n］s， n=8， 10） host and the effects of host-guest interaction on their mechanochromic luminescent（MCL） properties were studied by means of UV-Vis spectroscopy， fluorescence spectroscopy， nuclear magnetic resonance（NMR） and mass spectrometries. The results showed that CB［8］ and CB［10］ could form 2∶2 and 1∶2 inclusion complexes with guest molecules， respectively， with the enhancement of intermolecular π-π interaction of included molecules. Compared with free guest molecules， the fluorescence emissions of the host-guest complexes exhibited a significant red-shift（>100 nm） and further red-shift after grinding. The results also showed that the effects of different CB［n］s on the MCL properties of guest molecules differ. This study disclosed the effect of CB［n］-based host-guest interaction on the MCL properties of guest molecules， further providing a new way for the construction of novel MCL materials.



Design， Synthesis and Antifungal Activity of Novel Spiro-tetrahydroquinoline Derivatives

CHEN Wei, LAN Yuxin, JIN Yanxi, CHEN Yang, WU Run, CHU Chengwen, GAO Yanfeng

2023, 44(10):  20230179.  doi:10.7503/cjcu20230179

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In an effort to develop novel fungicides， a series of spiro-tetrahydroquinoline derivatives containing a barbituric acid moiety was designed and synthesized based on the natural products tetrahydroquinoline alkaloids and hydrogenated indolizines. The chemical structures were confirmed by nuclear magnetic resonance（¹H NMR and ¹³C NMR）. In vitro antifungal activity showed that at 50 mg/L， all the targets showed moderate inhibition. Especially， compound Ik exhibited more than 51.0% inhibition on all the tested fungi. The inhibition rates of compound Il against Helminthosporium maydis and Colletotrichum lagenarium were 78.1% and 77.8%， respectively， which were as high as chlorothalonil. The preliminary structure-activity relationships showed that the spiro-tetrahydroquinoline skeleton had potential antifungal activity， and the introducing of pyrazole pharmacophore could enhance the antifungal effective and expand the antifungal spectrum. Thus， the findings of this study will contribute to the design of novel spiro-tetrahydroquinoline derivatives as antifungal agents to control phytopathogenic fungi in agriculture.



Physical Chemistry

Iridium-based Catalyst Immobilized on Zeolite Subcrystals and Its Catalytic Transfer Hydrogenation Performance

WANG Shuqi, DU Ke, LI He, ZHANG Yahong

2023, 44(10):  20230224.  doi:10.7503/cjcu20230224

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By immobilizing homogeneous catalysts， the advantages of high reaction activity of homogeneous catalysts and separability of heterogeneous catalysts can be preserved simultaneously. This work used zeolite subcrystals with ultra-small size and ultra-large specific surface area as the carrier to immobilize the homogeneous transfer hydrogenation catalyst［Cp^*Ir（bpyO）］OH^- by physical adsorption， achieving the preparation of an immobilized catalyst ［Cp^*Ir（bpyO）］OH^-/Al-MFI-SC. The immobilization process and stability of the catalyst were preliminarily studied using UV-Vis to determine the amount of catalyst immobilized and demonstrate the stability of the immobilized catalyst. The characterization results of XRD， TEM， ICP-AES， Ar physical adsorption and desorption and XPS demonstrated that［Cp^*Ir（bpyO）］OH^- was uniformly immobilized on the surface of Al-MFI-SC. The strong interaction between the aluminum species in the zeolite subcrystals and the iridium complex was responsible for the stability of the immobilized catalyst. Finally， The catalyst was used for the catalytic transfer hydrogenation of cyclohexanone to cyclohexanol using glucose as the hydrogen donor and able to achieve a cyclohexanol yield of 75.4% under optimal reaction conditions. Compared with the homogeneous catalyst with the same weight percent of iridium， this immobilized catalyst showed better catalytic activity and good recycling performance. Meanwhile， the catalyst had a good reusability property. This work provides an idea for the preparation of immobilized catalysts for catalytic transfer hydrogenation reactions using zeolite subcrystal materials as the carrier.



Synthesis and Rheological Properties of Pillar［5］arene-polyethylene Glycol-conjugated Poly（pseudo）rotaxanes as Slide-ring Materials

LIU Shijia, LI Qian, CUI Kun, MA Zhi, ZHANG Danwei, WANG Hui, LI Zhanting

2023, 44(10):  20230211.  doi:10.7503/cjcu20230211

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A series of pillar［5］arene（P5）-polyethylene glycol（PEG）-linked polymers was prepared. The new polymers were revealed to form interpenetrated poly（pseudo）rotaxanes by the threading of the PEG chains into the cavity of P5 in solvent-free melted state. The interpenetration of the new poly（pseudo）rotaxanes were confirmed by proton nuclear magnetic resonance（¹H NMR） titration spectra experiments. X-ray powder diffraction， differential scanning calorimetry， and thermal gravimetric analysis experiments supported that the interpenetrating slide-ring polymers have good crystal structures， thermal performance and thermal stability， while the solid-state poly（pseudo）rotaxanes formed by PEG of approximately 1×10⁶ molecular weight exhibited good slide ring effects and their rheological behaviors were influenced by factors such as chain length， slide ring number， and slide ring motion. The results show that P5 is a useful macrocycle to form new solid-state slide-ring polymers that can exhibit good thermal stability， flexibility， and elastic mechanism responsiveness.



Theoretical Study of MB₈C₄（M=Ca， Sr， Ba） Molecular Wheels Clusters with Dodeca-coordination Number in Plane

FENG Linyan, HU Xiaobo, YAN Miao, MIAO Changqing, CHEN Rui, GUO Jinchang, WANG Yingjin

2023, 44(10):  20230281.  doi:10.7503/cjcu20230281

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Searching for the maximum coordination number in planar species has attracted considerable attention from scientists. Although transition metal-centered boron molecular wheel haven been reported previously， there are relatively few studies on molecular wheel structures doped with main group metals. In this work， the geometric structures， chemical bonding， and aromaticity are investigated systemically at the B3LYP/def2-TZVP level for MB₈C₄（M=Ca， Sr， Ba） clusters. The results show that the global minimum structure of CaB₈C₄ cluster adopts perfect planar molecular wheel structure. The centered calcium atom enclosed by a highly symmetric B₈C₄ ring possesses the coordinate number（CN） of 12. The molecular wheel SrB₈C₄ cluster has a C_4v symmetry with the out-of-plane distortion of the Sr atom， which are close in energy with elongated boron-carbon ring at CCSD（T）/def2-TZVP level. The latter has the actual coordination number of 8. Using a Ba， a larger atomic radius， to replace Sr in SrB₈C₄ cluster， the molecular wheel structure becomes less stable than elongated boron-carbon ring at CCSD（T）/def2-TZVP level. The natural bond orbital（NBO） analyses show that these systems undergo a large amount of charge transfer from alkaline earth metals to boron-carbon motifs. The MB₈C₄（M=Ca， Sr， Ba） molecular wheel can be formally described as ［M］²⁺［B₈C₄］^2- complexes. Chemical bonding analysis indicates that the dodeca-coordinated molecular wheel structure possesses 10σ and 8π conflicting aromaticity， which represents a counterexample in planar hyper-coordinated species. Adaptive natural density partitioning（AdNDP） analysis reveals that the interaction between the central alkaline earth metal and peripheral B₈C₄ monocyclic ring is governed by electrostatics and weakly covalent interaction. The latter mainly originate from contributions involving the M nd atomic orbitals， implying that alkaline earth metals mimic the behavior of transition metals. In addition， both the ring currents induced by an external magnetic field and the electron localization functions analysis results confirm the bonding characteristics of molecular wheel structures. We also predicted the infrared spectra of molecular wheel and elongated boron-carbon ring isomers， which provide theoretical guidance for experimental characterization of these clusters in future.



Preparation of Microcapsular Polycaprolactone Nanofibers by Emulsion Electrospinning and Their Protein Encapsulation

GAO Chong, ZHOU Quan, YANG Fan, REN Ruipeng, LYU Yongkang

2023, 44(10):  20230199.  doi:10.7503/cjcu20230199

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The microcapsular polycaprolactone（PCL） nanofibers were prepared by water-in-oil emulsion electrospinning as the carrier for protein encapsulation. The effects of ultrasonic emulsification， water addition amount， surfactant concentration and aqueous phase additives on the morphology of microcapsules in emulsion were investigated. The optimal preparative conditions to achieve the long-term stable polymer emulsion for nanofiber membrane are as follows： the dosage of amphiphilic triblock copolymer（Pluronic^® F108） as surfactant was 30%（mass fraction） in 10%（mass fraction） PCL spinning liquid， the oil-to-water volume ratio was 9∶1 and the aqueous phase was added extra glycerol and dopamine as additives. The properties of nanofibers were characterized by scanning electron microscopy， pore size distribution determination， etc. The results showed that the surface area of nanofiber was 31.784 m²/g， the internal microcapsule size distributed around 1.06 µm， and the load of bovine serum albumin（BSA） could reach 12.89 mg/g. Further， the release behavior of encapsulated BSA in nanofiber was studied. When the aqueous phase additives were added， the release rate of BSA was lower to 10.03% after 4 h by Coomassie blue staining test. The immobilization rate of protein was as high as 89.97%. In addition， the fluorescent labeled BSA was observed to be concentrated in the internal microcapsular structures of nanofiber verified by confocal laser scanning microscopy. The above characterization and analysis showed that a novel microcapsular structure of nanofiber for protein encapsulation was fabricated by emulsion electrospinning， which is different from the conventional hollow/core-shell structure and has a greater prospect of application in enzyme immobilization and biocatalysis.



Study on the Dielectric Relaxation Behavior of Fumed Silica Suspensions

LU Yuqiang, WU Xinjie, CHEN Zhen

2023, 44(10):  20230214.  doi:10.7503/cjcu20230214

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Colloidal suspensions of hydrophilic fumed silica in water and hydrophobic fumed silica in ethanol with different silica concentrations were prepared， and their dielectric spectra in the frequency range of 10² Hz to 10⁷ Hz were measured by means of impedance analyzer. Two dielectric relaxation behaviors are observed locating in the vicinity of 10⁴ Hz and 10⁵ Hz in these spectra， they were then fit in line with Cole-Cole equation and characteristic parameters of these relaxations were accurately obtained. It is found that， the dielectric relaxation behaviors of both suspensions vary regularly with the concentration of silica. Based on the relaxation features and the regularity of the variation of the features with the silica concentration， it is confirmed that the low- and high-frequency relaxations are ascribed to counterion polarization and interfacial polarization of silica aggregate， respectively， furthermore， the surface behavior， the dispersing state， and their variation with the change of the concentration of silica of hydrophilic fumed silica in water and of hydrophobic fumed silica in ethanol were discussed in detail.



Molecular Dynamics Simulation of Ion Adsorption at Water/Graphene Interface： Force Field Parameter Optimization and Adsorption Mechanism

LIAO Shouwei, LIU Yanchang, SHI Zenan, ZHAO Daohui, WEI Yanying, LI Libo

2023, 44(10):  20230155.  doi:10.7503/cjcu20230155

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The researches of salt solution confined in two-dimensional nanochannels are of great significance in a wide range of fields such as ion transport and sieving， supercapacitor， etc.， and molecular dynamics（MD） simulations in these research have become an important tool. However， it is difficult for common MD force fields（FFs） to accurately describe the ion-π interactions between two-dimensional materials（e.g.， graphene） and ions. In addition， the role of solvent effects on regulating ion adsorption on the solution/material interface also lacks in-depth studies. In this work， we have developed the FF parameters for the interactions between Li⁺， Na⁺， K⁺， Mg²⁺， Ca²⁺， Cl^‒ ions and graphene based on the potentials of mean force（PMFs）. The ion adsorption free energies on the graphene surface（in solution） simulated using the as-developed FF coincided with the quantum chemical calculations， which verified the accuracy of the as-developed FF. Furthermore， significant correlations were found between the ion hydration radius， the inflection point of the hydration number as the ion approaches the graphene， the position of the PMF_wat（the contributions of water to the PMFs of ion adsorption on graphene surface） minima and the position of the water layer on the graphene surface， elucidating the effects of ion dehydration and the water layers on graphene surface on PMF_wat. In addition， the salt solution（concentration of 1 mol/L）/graphene interface systems were simulated. For the above systems， ions simulated by common MD FFs hardly absorb on graphene surface， which indicates that ion-π interactions are indispensable for accurately simulating the salt solution-graphene systems.



Pyrolysis Mechanism of Flax Fiber Under Different Heating Rates

WANG Haochen, ZHAO Jun

2023, 44(10):  20230131.  doi:10.7503/cjcu20230131

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In order to study the pyrolytic mechanism of flax fiber at high temperature， the thermal kinetic analysis of pure flax fiber pyrolysis was firstly conducted under non-isothermal conditions in this paper. Initially， the pyrolytic properties of flax fiber were explored by thermogravimetric experiments at four heating rates. Then， the distribution of activation energy with conversion was calculated through six model-free methods， and the reaction model categories corresponding to different reaction stages were determined by two model-fitting methods. After combining the kinetic compensation effect analysis， the reaction model function of flax fiber pyrolysis was optimized and reconstructed. After that， the accuracy of the function was evaluated by model independence analysis. Finally， the pyrolytic products of flax fiber were summarized through mass spectrometry. The results indicated that the main reaction stage of flax fiber could be regarded as one independent sub-reaction， whose temperature interval was located in the pyrolysis temperature range of hemicellulose， cellulose， lignin and other components. The reaction mechanism of the main reaction stage was closer to F-series model. The reconstructed function demonstrated high fitting degree and reasonable accuracy. The pyrolysis products of flax fiber mainly contained 11 kinds of organic compounds， including aldehydes and olefin， etc.



Design and Construction of Increasing- and Reducing-drag Surfaces Inspired by Asymmetrical Structure of Snakeskin

WEN Zhixuan, XIN Weiwen, XU Qian, CHEN Weipeng, ZHOU Teng, FANG Ruochen, KONG Xiangyu, JIANG Lei

2023, 44(10):  20230116.  doi:10.7503/cjcu20230116

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Elaphe snake is a widely distributed snake， mainly living in coastal lowlands， inland plains， hills and mountains and other areas， which is quick to react and can move quickly in a variety of environments. In order to explore the mystery of the fast movement of the brocade snake， we observed the belly and the notum of the snake， and found that the two parts have completely different structures. In this regard， the scales on the notum of the snake show a transverse ordered convex structure， which is conducive to the movement of drag reduction. The scales of the belly of the snake present a longitudinal and orderly convex structure， which is conducive to increase the friction between the snake and the contact surface， so as to facilitate its rapid forward movement. Inspired by this， we take different surface structures of snakeskin belly and notum as models， starting from two aspects of structural differences and functional differences of snakeskin belly and notum， and prepare biomimetic materials with drag-increasing and drag-reducing functions respectively through the method of complex shape. In addition， we built a simulation model based on the microstructure of the belly and notum of the snake. Through finite element simulation analysis， we revealed that the special surface microstructure of the snake can effectively realize the drag-increasing and drag- reducing functions of the material surface. This work lays a foundation for the application of functional interface materials.



Preparation of Cu-based Hierarchical Pore ZSM-5 Zeolite Single Crystals and Their Catalytic Properties for Nitrobenzene Hydrogenation

XIE Xiaolan, LIU Zhan, LYU Jiamin, YU Shen, LI Xiaoyun, SU Baolian, CHEN Lihua

2023, 44(10):  20230109.  doi:10.7503/cjcu20230109

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In order to solve the problem of irreversible damage of zeolite framework in the process of intracrystalline hierarchically porous creation， a single crystal of silica-alumina zeolite ZSM-5（OMMS-ZSM-5） with hierarchically ordered macro-meso-microporous structure was successfully bottom-up in situ synthesized by using ordered macro- mesomicroporous carbon with anti-opal structure as a hard template， which possesses high external specific surface area（195.8 m²/g） and pore volume（0.27 cm³/g）. In addition， a series of Cu-OMMS-ZSM-5 catalysts with different Cu loadings（mass fraction： 1%， 5%， 10%） was prepared by impregnation method using OMMS-ZSM-5 as a carrier to investigate the catalytic ability of different metal loading catalysts in the liquid-phase hydrogenation reaction of nitrobenzene. The physical and chemical properties of the prepared catalysts were comprehensively characterized by SEM， TEM， XRD， NMR， N₂ adsorption-desorption， NH₃-TPD， XPS and H₂-TPR tests， which shows that the Cu elements are highly dispersed in the form of CuO， and the conversion of nitrobenzene reaches up to 96.8% and the selectivity of aniline reaches 99.3% when the loading is 9.58%（mass fraction）. Compared with the Cu-based micron ZSM-5 zeolite catalytic material， the aniline selectivity and the nitrobenzene conversion of Cu-OMMS-ZSM-5 are improved by 32.4% and 26.1%， respectively， and the high catalytic activity is maintained after three cycles.



A Fluorescent System Constructed by Non-conjugated Amines in Cyclohexanol Micelles Based on Simulating GFP Bioluminescence Mechanism

LAN Shuai, ZHANG Yu, DU Weilong, JIA Dandan, CAO Lei, WANG Dongjun

2023, 44(10):  20230096.  doi:10.7503/cjcu20230096

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A new fluorescent system was constructed based on simulating the luminescence mechanism of green fluorescent protein（GFP）， in which cycloalkyl alcohols formed micelles to protect non-conjugated organic amines to fluoresce efficiently. Only two simple procedures（mixing and aging） were necessary to fabricate the fluorescent system. The results show that the formation of the system is a physical process， and the micellar microenvironment has an important effect on the fluorescence properties. The luminescent system has the characteristics of high fluorescence intensity and strong temperature sensitivity， which can be applied in the fields of cell staining imaging and temperature sensing. At the same time， this work provides a new green， simple and low-cost method for the preparation of efficient non-conjugated luminescence systems.



Polymer Chemistry

Synthesis of a Multiple Stimulus-responsive Multicolor Fluorescent Hydrogel

ZOU Shaoshuang, YANG Peng, LIU Tao

2023, 44(10):  20230175.  doi:10.7503/cjcu20230175

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On the basis of molecular structure design theory， a novel fluorescent ligand， 6-｛3-［2-（methacryloyloxy） ethyl］ ureido｝ picolinic acid（UPA）， was designed and synthesized. The hydrogels were prepared by the free radical polymerization with UPA and zwitterionic sulfobetaine（DMA） as monomers， clay as a physical crosslinker. The fluorescent ligand was introduced into the hydrogel structure by UV light curing， and then the lanthanide complex was formed in the hydrogel after Eu³⁺ or Tb³⁺ coordination， and a new intelligent rare-earth hybrid hydrogel material with high mechanical strength， good self-healing properties， multiple stimulus responsiveness（temperature， pH， the intensity of ion， etc.） and high luminescence efficiency was constructed， the problems such as poor stability and easy fluorescence quenching in the aqueous phase of rare earth luminescent materials， and poor mechanical properties and single function of traditional hydrogels were solved. It provides a new idea for the preparation of materials in the fields of information security and encryption， biological imaging， fluorescent labeling and so on.



Preparation of PLGA-Curcumin Nanoparticles and Evaluation of Its Anti-inflammatory Properties in vitro

LI Zhen, HAO Kai, HE Chaoliang, TIAN Huayu

2023, 44(10):  20230154.  doi:10.7503/cjcu20230154

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In this paper， we used polyvinyl alcohol（PVA） aqueous solution as the aqueous phase， poly lactic- co-glycolic acid（PLGA） and curcumin（Cur） dichloromethane solution as the oil phase to prepare curcumin-encapsulated PLGA nanoparticles（PLGA@Cur NPs） by a water-in-oil-in-water double emulsion method. PLGA@Cur improved the dispersion of curcumin and enhanced its antioxidant and anti-inflammatory properties. The results of dynamic light scattering（DLS） and scanning electron microscopy（SEM） showed that PLGA@Cur NPs was homogeneous and spherical with an average size of （340.1±14.9） nm， a polydispersity index（PDI） of （0.22±0.01） and a potential of （-20.20±4.17） mV， and had good stability. The drug loading and encapsulation rate of Cur in PLGA@Cur NPs were determined by high performance liquid chromatography（HPLC）， and the encapsulation rate was 15.1% and the drug loading rate was 34.9%. The results at the cellular level showed that PLGA@Cur NPs had good biocompatibility and could scavenge a variety of reactive oxygen species（ROS）， and effectively reduced the level of pro-inflammatory cytokines secreted by RAW 264.7 macrophages and alleviate inflammation at the cellular level.



NaBH₄/Ziegler-Natta Rare Earth Catalyst Reduction System for Reduction of Liquid Terminated-carboxyl Fluoroelastomers

CHANG Yunfei, LIAO Mingyi, YUAN Gaofei

2023, 44(10):  20230133.  doi:10.7503/cjcu20230133

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Sodium borohydride/Ziegler-Natta rare earth catalyst reduction system（NaBH₄/Ziegler-Natta） was used to reduce liquid terminated-carboxyl fluoroelastomers（LTCFs）. LTCFs were efficiently converted to the corresponding liquid terminated-hydroxyl fluoroelastomers（LTHFs） via a simple one-pot method. The reductive rate of LTHFs was analyzed by chemical titration. The structures of LTCFs and LTHFs were analyzed by Fourier transform infrared spectroscopy（FTIR）， ¹H nuclear magnetic resonance（¹H NMR） spectroscopy and ¹⁹F nuclear magnetic resonance（¹⁹F NMR） spectrocopy. The results show that —C=C— and carboxyl groups of LTCFs were reduced to —C—C— and —OH efficiently at ambient temperature and the reduction rate reached 90% under optimum reaction conditions.