Chemical Research in Chinese Universities

Special Column on Nanoparticles/MOFs Synergistic Catalysis

OUYANG Junchen, ZHANG Suoying and HUO Fengwei

2022, 38(6): 1-2. doi:10.1007/s40242-022-6000-3

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Recent Advances on Confining Noble Metal Nanoparticles Inside Metal-Organic Frameworks for Hydrogenation Reactions

LIN Tian, WANG Haowu, CUI Chengqian, LIU Wei, LI Guodong

2022, 38(6): 1309-1323. doi:10.1007/s40242-022-2250-3

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Hydrogenation reaction is one of the pillars of the chemical industry for the synthesis of drugs and fine chemicals. To achieve high catalytic performance, it is still highly desirable for constructing novel supported metal catalysts. Different from conventional supports like metal oxides, zeolites and carbon materials, metal-organic frameworks(MOFs) as the emerging porous materials have Hexhibited great potential to host metal nanoparticles (NPs) for achieving hydrogenation reactions with high catalytic efficiency, due to their unique porous structures. Recently, many progresses have been made, and thus, it is necessary to summarize the recent progresses on confining metal NPs inside MOFs for hydrogenation reactions. In this review, we first introduced the general synthesis methods for confining noble metal NPs inside MOFs. Then, the applications of noble metal NPs/MOFs catalysts in hydrogenation reactions were summarized, and the synergistic catalytic performances among noble metal NPs, metal nodes, functional groups, and pore channels in MOFs were illustrated. Subsequently, the hydrogen spillover effect involved in the hydrogenation reactions was discussed. Finally, we provide an outlook on the future research directions and challenges of confining noble metal NPs inside MOFs for hydrogenation reactions.

Recent Advances of Metal-Organic Frameworks-based Nanozymes for Bio-applications

WANG Yuda, ZULPYA Mahmut, ZHANG Xinyao, XU Shihan, SUN Jiao, DONG Biao

2022, 38(6): 1324-1343. doi:10.1007/s40242-022-2256-x

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Artificial nanoenzymes with enzyme-like catalytic activity have gradually become an alternative to natural enzymes due to their low production cost, high stability, and good tolerance. In recent years, various enzyme mimics have emerged with the rapid development of nano-teclnology. Metal-organic frameworks(MOFs) are a novel class of porous inorganic-organic hybrid materials made from metal ions/clusters and organic ligands, and MOFs-based nanozymes show great prospect in biosensing, biocatalysis, biomedical imaging, and therapeutic applications, due to unique properties, such as high specific surface area, high porosity, tunable morphology, and excellent biocatalytic properties. In this paper, the recent progresses concerning MOFs-based nanozymes are systematically summarized, including the synthesis, design strategies and related applications, which are divided into two major categories, namely, MOFs structured nanoenzymes and MOFs composite structured nanoenzymes. Meanwhile, the applications of various classifications of MOFs research are introduced. At the end, current challenges and future perspectives of MOFs-based nanozymes are also discussed. It is highly expected that this review on this important area can provide a meaningful guidance for tumor therapy, biosensing and other aspects.

Bimetallic Au-Pd NPs Embedded in MOF Ultrathin Nanosheets with Tuned Surface Electronic Properties for High-performance Benzyl Alcohol Oxidation

GUO Taolian, BAO Shutong, GUO Jie, CHEN Wu, WEN Lili

2022, 38(6): 1344-1348. doi:10.1007/s40242-022-2210-y

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Bimetallic Au-Pd nanoparticles(NPs) with synergistic effect between Au and Pd atom have shown excellent catalytic activity toward benzyl alcohol oxidation. The catalytic activities of metal NPs supported within metal-organic frameworks (MOFs) are affected by the electronic interactions between metal NPs and MOFs. Taking the advantages of ultrathin nanosheets, we confine the highly dispersed Au-Pd NPs within ultrathin nanosheets of MOF-Ni(NMOF-Ni) to fabricate Au_xPd_y@NMOF-Ni as catalysts. Under base-free and atmospheric pressure conditions, the as-prepared Au_xPd_y@NMOF-Ni catalysts exhibit superior activity and selectivity for benzyl alcohol oxidation. This work highlights the synergistic effects among different components in composite catalysts effectively improving the activity and offers a new way for designing efficient catalysts toward benzyl alcohol oxidation.

High-performance Removal of Tetracycline Enabled by Fe⁰ Nanoparticles Supported on Carbon@ZIF-8

XIAO Meng, QI Wenqian, JIA Shuanghui, PANG Mengting, SHI Fengcheng, MAO Hui

2022, 38(6): 1349-1355. doi:10.1007/s40242-022-2255-y

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Significant concerns have been raised over the removal of antibiotics, such as tetracyclines(TC) in aquatic environments. Herein, we synthesized a new type of heterogeneous catalyst by supporting Fe⁰ nanopartciles(FeNPs) onto carbon coated ZIF-8 (C@ZIF-8). The carbon layer formed by glucose was beneficial to maintain the morphology and porous structure of ZIF-8, which can also appropriately improve the hydrophobicity of ZIF-8 for enriching the TC. The as-prepared FeNPs-C@ZIF-8 catalyst featured an extreme large specific surface area(1122.16 m²/g), and the supported FeNPs with an average diameter of 6.13 nm exhibited a high dispersity on the supporting matrix of C@ZIF-8. For the removal of tetracycline, the large specific surface area of FeNPs-C@ZIF-8 allowed for an easy access of tetracycline to the FeNPs, while the highly dispersed FeNPs served as actived sites for the efficient degradation of tetracycline. A synergistic effect between adsorption and catalytic degradation of FeNPs(5%, mass fraction)-C@ZIF-8 was proven to be responsible for the high-performance removal of tetracycline with the removal efficiency high up to 93.02% at pH 5, 25℃. The FeNPs-C@ZIF-8 was capable of recycling after activation with supplementary Fe⁰, which still maintained a high removal efficiency of 75.52% in the 5th cycle within 20 min.

Synergistic Catalysis of Enzymes and Biomimetic MOFs:Immobilizing Cyt c on Two-dimensional MOFs to Enhance the Performance of Peroxidase

WANG Yitong, MENG Fanchen, SU Ruifa, SUN Changrui, HAN Qianqian, ZHANG Weina, ZHANG Suoying

2022, 38(6): 1356-1360. doi:10.1007/s40242-022-2257-9

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Metal-organic frameworks(MOFs) have been widely regarded as promising carriers for enzyme immobilization owing to their advantages in improving loading and regulating interaction with enzymes. However, they are still suffering from the problems of slow mass transfer and compromising activity. In this paper, the active two-dimensional(2D) MOF of Cu-TCPP(Fe)[TCPP=tetrakis(4-carboxy-phenyl)porphyrin], which possesses the biomimetic architecture of peroxidase, was adopted to anchor cytochrome(Cyt c) for the enhancement of catalytic activity. The atomic/nanometer thickness and micrometer lateral dimension of 2D MOFs can ensure the full exposure of immobilized enzymes and a shorter diffusion distance for the reactant molecules. Besides, the active carrier can provide synergistic catalysis and activity compensation during the reaction. When tested in the decomposition reaction of H₂O₂, Cyt c/Cu-TCPP(Fe) exhibited nearly twice catalytic activity and an accelerated catalytic rate compared to free Cyt c.

M_xCo₃O₄/g-C₃N₄ Derived from Bimetallic MOFs/g-C₃N₄ Composites for Styrene Epoxidation by Synergistic Photothermal Catalysis

REN Fengdi, GAO Qiqin, CHEN Yuzhen

2022, 38(6): 1361-1367. doi:10.1007/s40242-022-2292-6

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Although metal-organic frameworks(MOFs) have been widely reported as precursors for obtaining various porous materials in recent years, the limited MOF types and monofunctional active site of MOF-based catalysts remain to be hard to crack. Herein, bimetallic MOFs, MCo-ZIFs stabilized by graphitized carbon nitride(g-C₃N₄) and their pyrolytic M_xCo₃O₄/g-C₃N₄ hybrids(M=Zn, Cu, Fe, Ni) have been designedly synthesized. The obtained M_xCo₃O₄/g-C₃N₄ hybrids display synergistic photothermal effect from both M_xCo₃O₄ and g-C₃N₄ under visible light irradiation. Significantly, the solution temperature can be heated from room temperature(20℃) to 66℃ after 40 min irradiation. Therefore, the catalytic activity of M_xCo₃O₄/g-C₃N₄ exceeds those of most reported catalysts under mild reaction conditions. The optimal Zn_xCo₃O₄/g-C₃N₄ catalyst realizes 96% conversion and 75% selectivity toward styrene oxide within 20 min. Incredibly, the Cu_xCo₃O₄/g-C₃N₄ could achieve up to 89% selectivity toward styrene oxide. To our knowledge, this is the first report about the novel photothermal effect of ZIFs-derived metal oxides.

Amphiphilic Block Copolymer Micelles for Gene Delivery

LI Qin, JIN Bixin, LUO Yunjun, LI Xiaoyu

2022, 38(6): 1368-1379. doi:10.1007/s40242-022-2005-1

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Gene therapy is a promising method to treat acquired and inherited diseases by introducing exogenous genes into specific recipient cells. Polymeric micelles with different nanoscopic morphologies and properties hold great promise for gene delivery system. Conventional cationic polymers, poly(ethyleneimine)(PEI), poly(L-lysine)(PLL), poly(2-dimethyla-minoethyl methacrylate)(PDMAEMA) and novel cationic polymers poly(2-oxazoline)s(POxs), have been incorporated into block copolymers and decorated with targeting moieties to enhance transfection efficiency. In order to minimize cytotoxicity, nonionic block copolymer micelles are utilized to load gene through hydrophilic and hydrophobic interactions or covalent conjugations, recently. From our perspective, properties(shape, size, and mechanical stiffness, etc.) of block copolymer micelles may significantly affect cytotoxicity, transfection efficiency, circulation time, and load capacity of gene vectors in vivo and in vitro. This review briefly sums up recent efforts in cationic and nonionic amphiphilic polymeric micelles for gene delivery.

Bismuth/Graphdiyne Heterostructure for Electrocatalytic Conversion of CO₂ to Formate

DU Yuncheng, ZHENG Xuchen, XUE Yurui, LI Yuliang

2022, 38(6): 1380-1386. doi:10.1007/s40242-022-2091-0

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Electrocatalytic CO₂ reduction is great promising in alleviating the excessive CO₂ emission and the conversion to valuable productions. Herein we report the in-situ controlled growth of Bismuth nanoflower/graphdiyne heterostructures(Bi/GDY) for efficient CO₂ conversion toward formate. Based on GDY, the obtained electrocatalyst exhibits a partial current density of 19.2 mA/cm² and high reaction selectivity towards formate with a high Faradic efficiency of 91.7% at ‒1.03 V vs. RHE, and an energy efficiency of 58.8%. The high formate yield rates could be maintained at around 300 μmol/(cm²·h) over a wide potential range. Detailed characterizations show that the unique interface structures between GDY and Bi can enhance the charge transfer ability, increase the number of active sites, and improve the long-term stability, and finally reach high-performance electrocatalytic conversion of CO₂ to formate.

A Label-free Photoelectrochemical Sensor Based on Bi₂S₃@Nitrogen Doped Graphene Quantum Dots for Ascorbic Acid Determination

WU Zhifang, LIANG Zhishan, HE Ziqian, WANG Tianqi, XIAO Ren, HAN Fangjie, ZHAO Zhengzheng, HAN Dongfang, HAN Dongxue, NIU Li

2022, 38(6): 1387-1393. doi:10.1007/s40242-022-2095-9

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We report a photoelectrochemical(PEC) sensor for selective detection of ascorbic(AA) by introducing Z-scheme Bi₂S₃@nitrogen doped graphene quantum dots(Bi₂S₃@NGQDs) heterojunctions as efficient photoactive species. The Bi₂S₃@NGQDs were successfully prepared by a simple hydrothermal process, and the microstructures and components were investigated by various characterized techniques. The photocurrent of the Bi₂S₃@NGQDs-based sensor increased significantly in the presence of AA and showed excellent selectivity and stability for AA detection in the presence of some other antioxidants and small molecules. A wide linear range of 0.1-5 μmol/L and 5-1380 μmol/L was achieved for the AA detection with a detection limit of 36 nmol/L(S/N=3). Moreover, the proposed PEC sensor achieved the determination of AA in real red peppers and commercially available vitamin C tablets samples.

Visualization of Ferroelectric Domains in Thin Films of Molecular Materials Using Confocal Micro-Raman Spectroscopy

ZHOU Wenqin, FENG Zijie, XIONG Yuan, DU Guowei, LIN Xiumei, SU Qidong, LOU Yuheng, AN Shili, YOU Yumeng

2022, 38(6): 1394-1399. doi:10.1007/s40242-022-2102-1

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Ferroelectrics are an important class of functional materials. Among all their unique properties, the study of their ferroelectric domains and domain walls is of great interest due to their importance in ferroelectric applications. There are many methods to characterize ferroelectric domains, namely, scanning probe microscopy, optical microscopy, electron microscopy, etc. Currently, newly emerged molecular ferroelectrics are attracting much attention from chemists, physicists and researchers in material sciences due to their structural flexibility, light mass, simple fabrication, etc. However, for the characterization of molecular ferroelectric domains, most conventional methods require either a complicated preparation process or direct contact between physical probes and material surfaces, limiting the development of molecular ferroelectric materials. In this report, we have demonstrated that confocal micro-Raman spectroscopy, as a nondestructive and noncontact in-situ method, is very suitable for studying the ferroelectric polarization and structures of domains in molecular ferroelectrics. Taking recently reported molecular ferroelectric trimethylchloromethyl ammonium trichlorocadmium(II) (TMCM-CdCl₃) as an example, the non-180° domains have been characterized and visualized at different temperatures. Such a simple and extendable method requires minimum sample preparation, which would further benefit the research of molecular ferroelectric domain engineering and promote the miniaturization and integration of molecular ferroelectric films.

Modification of PAE-degrading Esterase(CarEW) for Higher Degradation Efficiency Through Integrated Homology Modeling, Molecular Docking, and Molecular Dynamics Simulation

ZHOU Mengying, LI Yu

2022, 38(6): 1400-1413. doi:10.1007/s40242-022-1433-2

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Six phthalate acid esters(PAEs) priority pollutants[dimethyl phthalate(DMP), diethyl phthalate(DEP), dibutyl phthalate (DBP or DNBP), di-n-octyl phthalate(DNOP), di 2-ethyl hexyl phthalate(DEHP), and butyl benzyl phthalate(BBP)] were opted as the research object. PAE-degrading esterase CarEW(PDB ID:1C7I) isolated from Bacillus subtilis acting as a template and an iterative saturation mutation strategy was adopted to modify key amino acids to attain efficient PAE-degrading esterase substitutes with a reasonable structure constructed by homology modeling method. Present study designed a total of 285 unit-site and multi-site substitutions of PAE-degrading esterase using the homology modeling method. Among them, 207 PAE-degrading esterase substitutions, which contained the 6-site PAE-degrading esterase substitute 1C7I-6-9 with 84.21% enhancement intensity of degradation ability revealed better degradability to all the 6 PAEs after modification. Moreover, molecular dynamics simulation based on the Taguchi method reported the optimal external application environment for PAE-degrading esterase substitutes as follows:pH=6, T=35℃, the rhamnolipid concentration was 50 mg/L, the molar ratio of nitrogen to phosphorus(N:P) was 10:1, the concentration of H₂O₂ was 50 mg/L, and the voltage gradient was 1.5 V/cm. The degradation ability of PAE-degrading esterase substitutes was found to be elevated by 13.04% as compared to that of the blank control under the optimal condition. Moreover, 11 highly efficient PAE-degrading esterase substitutes with thermal stability were designed.

Theoretical Study of Stability and Electronic Characteristics in Various Complexes of Psoralen as an Anticancer Drug in Gas Phase, Water and CCl₄ Solutions

MOHAMMADI Marziyeh, MAHINIAN Maryam, KHANMOHAMMADI Azadeh

2022, 38(6): 1414-1424. doi:10.1007/s40242-022-1475-5

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The present research employs density functional theory(DFT) computations to analyze the structure and energy of complexes formed by psoralen drug with alkali(Li⁺, Na⁺, K⁺) and alkaline earth(Be²⁺, Mg²⁺, Ca²⁺) metal cations. The computations are conducted on M06-2X/aug-cc-pVTZ level of theory in the gas phase and solution. The Atoms in Molecules(AIM) and natural bond orbital(NBO) analyses are applied to evaluating the characterization of bonds and the atomic charge distribution, respectively. The results show that the absolute values of binding energies decrease with going from the gas phase to the solution. Furthermore, the considered complexes in the water(as a polar solvent) are more stable than the CCl₄(as a non-polar solvent). The DFT based chemical reactivity indices, such as molecular orbital energies, chemical potential, hardness and softness are also investigated. The outcomes show that the considered complexes have high chemical stability and low reactivity from the gas phase to the solution. Finally, charge density distributions and chemical reactive sites of a typical complex explored in this study are obtained by molecular electrostatic potential surface.

Preparation of Three-dimensional Graphene-based Sponge as Photo-thermal Conversion Material to Desalinate Seawater

ZHANG Huan, LIU Huie, CHEN Shuang, ZHAO Xinxin, YANG Fan, TIAN Xiaowen

2022, 38(6): 1425-1434. doi:10.1007/s40242-022-1500-8

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Water shortage has become one of the major threats to human society over the past centuries. The new interfacial solar evaporation is undoubtedly an attracting technology to solve this problem. Herein, graphene aerogel(GA) and graphene oxide/melamine sponge composite material(GO-MS) were prepared through a two-step reduction and one-step freezing method as photo-thermal materials to evaporate pure water and seawater. The proper concentrations of the graphene oxide(GO) dispersion for their preparation were investigated, which is 7 mg/mL for GA, and 5 mg/mL for GO-MS. The evaporation rates of GA are 1.40 kg/(m²·h) for pure water and 1.21 kg/(m²·h) for seawater, while for GO-MS it is 1.63 kg/(m²·h) for pure water and 1.45 kg/(m²·h) for seawater, respectively. The composite material not only reduces the usage of GO, but also shows better photo-thermal conversion properties. Furthermore, the heat loss of evaporation system was calculated and the method of further enhancing photo-thermal conversion efficiency was deduced, which will provide a strong basis for guiding the design and development of graphene based three-dimensional materials and further exploration in this field.

Electric Field and Ion Diffusion Triggered Precisely Regulated Construction of Micron-scale Water-based Polymer Films:a Detailed Mechanistic Exploration

WANG Dan, LIU Jinfang, YANG Shuqi, JI Xin, WANG Yuliang, OMONIYI Ahmed Olalekan, ZHANG Jianfu, SU Zhongmin

2022, 38(6): 1435-1445. doi:10.1007/s40242-022-1503-5

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Water-based polymer films can be readily deposited onto a wide range of metallic materials as an environmentally friendly coating through the demulsification-induced fast solidification(DIFS) method. However, there is still a lack of in-depth understanding of the demulsification process of the water-based emulsions and their deposition processes. Herein, we demonstrate that the build-up process of the commercial water-based micron-scale waterborne polyurethane, polyvinyl acetate, polyurethane acrylate, and natural rubber polymer films is affected by the collective effect of electric field and ion diffusion exerted by anode-cathode electrode pairs, applied voltage, conduction time, electrode distance, and emulsion species. A structural investigation of as-prepared polymer films allows us to propose two new structure build-up models. During a flat film deposition, isolated islands are formed first and grow on the substrate surface, and eventually, their mutual coalescence forms the final layer. Whereas, for a convex layer formation, the layer is first formed in the middle of the substrate and then grows toward the sides of the convex structure of the substrate. The results presented in this work expand the understanding of the mechanism of the DIFS process and may provide some new insights into structure-oriented multifunctional material design.

Biomass-based Carbon Dots as Peroxidase Mimics for Colorimetric Detection of Glutathione and L-Cysteine

LIU Junxue, WANG Yufei, MA Wenyan, ZONG Siyu, LI Jiyang

2022, 38(6): 1446-1452. doi:10.1007/s40242-022-2021-1

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Biomass-carbon dots(named as B-CDs) have been successfully prepared via facile one-step hydrothermal reflux treatment at a low temperature from passion fruit peel. The as-prepared B-CDs had a uniform sphere morphology and size of 1-3 nm, which possessed rich nitrogen/oxygen-containing functional groups. B-CDs could imitate peroxidase and accelerate the reaction process of H₂O₂ oxidizing the substrate 3,3',5,5'-tetramethylbenzidine(TMB), which caused an obvious color change in the solution due to the oxidization of achromic TMB into blue oxidation product(ox-TMB) with an absorption peak at 652 nm. Furthermore, the product could be further reduced to native colorless TMB by the reducing agent glutathione or L-Cysteine. Thus, depending on the peroxidase-like properties of B-CDs, we developed a colorimetric approach to detecting both glutathione and L-Cysteine, which showed superior selective and sensitive detection towards glutathione and L-Cysteine in a linear range of 0-20 µmol/L. The limits of detection were 0.62 and 0.58 µmol/L, respectively.

Fabricating UCNPs-AuNPs Fluorescent Probe for Sensitive Sensing Thiamphenicol

YI Jiaqi, LI Xiaoshuang, CUI Di, HAN Lixia, JIANG Wei, ZHANG Renguo, NIU Na, CHEN Ligang

2022, 38(6): 1453-1460. doi:10.1007/s40242-022-2032-y

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Anovel fluorescent probe has been constructed based on fluorescence resonance energy transfer(FRET) between upconversion nanomaterials(UCNPs) NaYF₄:Yb,Er and gold nanoparticles(AuNPs). The fluorescent "off-on" switching was formed for the detection of thiamphenicol(TAP) in egg samples. The fluorescence of UCNPs can be quenched to a certain degree by AuNPs. After adding TAP, the AuNPs generated aggregation and the fluorescence of UCNPs was recovered. The synthesized amination UCNPs and AuNPs were characterized by Fourier transform infrared spectroscopy(FTIR), UV-Vis, X-ray diffraction(XRD), energy dispersive spectrometer(EDS), and transmission electron microscope(TEM) techniques for observation and confirmation. As a model target, the detection of TAP has two linear ranges in the buffer solution within 0.01-0.1 μmol/L and 0.1-1 μmol/L using this fluorescent probe. The detection limit was obtained to be 0.003 μmol/L(S/N=3), which is favorable for trace analysis. The recovery of TAP from 98.2% to 105.3% was obtained, and the relative standard deviation(RSD) was from 2.5% to 4.3%. Furthermore, the method established in this study based on the UCNPs auto-low background fluorescence has high selectivity and strong ability to eliminate interference, which is beneficial to analyzing complex samples.

Rational Design of a Near-infrared Fluorescent Material with High Solid-state Efficiency, Aggregation-induced Emission and Live Cell Imaging Property

SHANG Anqi, ZHAO Lele, LI Zhenhua, CHENG Zhuang, JIN Haixu, FENG Zijun, CHEN Zhijun, ZHANG Haiquan, LU Ping

2022, 38(6): 1461-1466. doi:10.1007/s40242-022-2046-5

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Near-infrared(NIR) fluorescent materials with high photoluminescent quantum yields(PLQYs) have wide application prospects. Therefore, we design and synthesize a D-A type NIR organic molecule, TPATHCNE, in which triphenylamine and thiophene are utilized as the donors and fumaronitrile is applied as the acceptor. We systematically investigate its molecular structure and photophysical property. TPATHCNE shows high T_gof 110℃ and T_d of 385℃ and displays an aggregation-induced emission(AIE) property. A narrow optical bandgap of 1.65 eV is obtained. The non-doped film of TPATHCNE exhibits a high PLQY of 40.3% with an emission peak at 732 nm, which is among the best values of NIR emitters. When TPATHCNE is applied in organic light-emitting diode(OLED), the electroluminescent peak is located at 716 nm with a maximum external quantum efficiency of 0.83%. With the potential in cell imaging, the polystyrene maleic anhydride(PMSA) modified TPATHCNE nanoparticles(NPs) emit strong fluorescence when labeling HeLa cancer cells, suggesting that TPATHCNE can be used as a fluorescent carrier for specific staining or drug delivery for cellular imaging. TPATHCNE NPs fabricated by bovine serum protein(BSA) are cultivated with mononuclear yeast cells, and the intense intracellular red fluorescence indicates that it can be adopted as a specific stain for imaging.

Side Chain Functional Conjugated Porous Polymers for NIR Controlled Carbon Dioxide Adsorption and Release

CHEN Liquan, LI Dawei, REN Jinghan, LI Yameng, GAO Dong, XING Chengfen

2022, 38(6): 1467-1474. doi:10.1007/s40242-022-2047-4

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Conjugated porous polymers exhibit considerable advantage as attractive candidate for carbon dioxide(CO₂) capture. However, the regeneration of the CO₂ still faces the problem of high energy cost. Here we synthesize a near-infrared region(NIR) light responsive conjugated porous polymer(PDPP-Gu) {DPP=3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione} by constructing porous amorphous networks with a side chain engineering strategy to regulate CO₂ adsorption and release through photothermal conversion. The PDPP-Gu is featured by a torsional conjugated backbone as well as a functional side chain of guanidino group. The donor-acceptor configuration of PDPP-Gu afforded strong absorption in the NIR and an excellent photothermal conversion capability of up to 48.8%, as well as a high surface energy. Moreover, guanidine modified side chain further enhanced the CO₂-polymers interactions, resulting in a high CO₂ selective adsorption capacity(0.8 mmol/g) at 273 K, 1 bar(1 bar=10⁵ Pa). The adsorbed CO₂ can be released under NIR light irradiation. This strategy of molecule design combined the dual features of photothermal conversion and gas adsorption, which is beneficial for the development of materials to dynamically control the adsorption and release of CO₂ through NIR light.

Surfaced-modified TiO₂ Nanofibers with Enhanced Photodegradation Under Visible Light

PENG Hao, JIANG Jiaxin, LIU Yifang, WANG Xiang, LI Wenwang, ZHENG Gaofeng

2022, 38(6): 1475-1481. doi:10.1007/s40242-022-2056-3

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Asynchronized surface modification method based on coaxial electrospinning was developed to fabricate high-efficiency photodegradative nanofiber for water purification. TiO₂ nanoparticles assembled uniformly on the surface of polycaprolactone(PCL) nanofibers to form composite nanofibers through one step process. The maximal content of Ti element was 25.6%(mass fraction) in the PCL/TiO₂ composite nanofibrous membrane, which exhibited hydrophilicity and excellent photodegradation under visible light in water. The Rhodamine B dye degraded 96.17% in 120 min under visible light by the PCL/TiO₂ composite membrane. The adsorption behavior fitted Langmuir model well and indicated chemical related adsorption. This PCL/TiO₂ composite nanofibrous membrane has super degradation properties and displays great application potential to environmental protection.

Analysis on First-stage Ignition of n-Heptane at Low Temperatures with a Lumped Skeletal Mechanism

XIAO Jiayu, WANG Jingbo, WANG Fan, LI Xiangyuan

2022, 38(6): 1482-1491. doi:10.1007/s40242-022-2066-1

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Two-stage ignition exists in the low-temperature combustion process of n-heptane and the first-stage ignition also shows a negative temperature coefficient(NTC) phenomenon. To study key reactions and understand chemical principles affecting the first-stage ignition of n-heptane, a lumped skeletal mechanism with 62 species is obtained based on the detailed NUIGMech1.0 mechanism using the directed relation graph method assisted by sensitivity analysis and isomer lumping. The lumped mechanism shows good performance on ignition delay time under wide conditions. The study revealed that the temperature after the first-stage ignition is higher and a larger amount of fuel is consumed at lower initial temperatures. The temperature at the first-stage ignition is relatively insensitive to the initial temperature. Further sensitivity analysis and reaction path analysis carried out based on the lumped mechanism show that the decomposition of RO₂ to produce alkene and HO₂is the most important reaction to inhibit the first-stage ignitions. The chain branching explosion closely related to the first-stage ignition will be terminated when the rate constant for the RO₂ decomposition is larger than that of the isomerization of RO₂ to produce QOOH. The NTC behavior as well as other characteristics of the first-stage ignition can be rationalized from the competition between these two reactions.

A New Approach to the Synthesis of Bergapten

CAI Xiaoqing, JI Dongxin, LIU Jiageng, HU Maolin, JIN Zhimin

2022, 38(6): 1492-1496. doi:10.1007/s40242-022-2089-7

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In this study, bergapten was synthesized in a yield of 55% from phloroglucinol as starting material, via a novel approach including monomethylation, Hoesch reaction, acetylation, deacetoxylation, Pechmann condensation and 2,3-dichloro-5,6- dicyano-1,4-benzoquinone(DDQ) dehydrogenation. With the adoption of the acetylation of enol tautomer, the deacetoxylation and the DDQ dehydrogenation, the novel approach differs greatly from the processes reported previously, though the starting material was the same or similar to those used on previous synthetic processes. The newly adopted reaction underwent easily, affording all reactions in high yields, especially acetylation and deacetoxylation and DDQ dehydrogenation in almost quantitative yields, ensuring a final yield higher than those previously reported.

Self-assembled Nanosheets of Perylene Monoamide Derivative as Sensitive Fluorescent Biosensor for Exonuclease III Activity

QIN Yang, YANG Yunhan, HE Ran, ZHOU Laicheng, ZHANG Ling

2022, 38(6): 1497-1503. doi:10.1007/s40242-022-2093-y

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Enzymes containing 3'→5' exonuclease activities play an important role in various key cellular and physiological processes. The development of fluorescence biosensor is an efficient method to detecting enzyme activity. Herein, a fluorescence resonance energy transfer(FRET) "on" and "off" strategy for detecting exonuclease III(Exo III) activity has been developed. We report here that the double-stranded DNA(dsDNA) enables to bind tightly to self-assembled nanosheets of cationic perylene monoimide derivative(PMI-O7) through electrostatic interaction, and the 6-carboxyfluorescein(FAM)-modified dsDNA could be efficiently quenched via FRET between FAM and PMI-O7. Upon the addition of Exo III, the dsDNA will be digested and the FAM fluorophore will be released, resulting in the fluorescence recovery of FAM. This method provides a simple and sensitive biosensor platform with a low detection limit of 0.077 U/mL for Exo III. Importantly, this method exhibits similar and calibration curves for the detection of Exo III in both buffer and fetal bovine serum samples, indicating that this platform has potential to detect Exo III activity in complex samples.

Ni-W Catalysts Supported on Mesoporous SBA-15: Trace W Steering CO₂ Methanation

HE Kai, LIU Shijia, ZHAO Guiyan, QIN Yucai, BI Yanfeng, SONG Lijuan

2022, 38(6): 1504-1511. doi:10.1007/s40242-022-2096-8

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Aseries of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(Ni_xW/SBA-15, Ni-5%, x=1,10,50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H₂-temperature programmed reduction(H₂-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H₂-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H₂WO₄ can significantly improve Ni dispersion on SBA-15 (Ni₅₀W/SBA-15) with Ni⁰ andnon-stoichiometric WO_x species as small as ca. 3.6 nm. The prepared Ni_xW/SBA-15 was utilized for CO₂ hydrogenation, which showed that a higher W content restrained the CO₂ hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni₅₀W/SBA-15 catalyst showed the best performance with a 93.3% CO₂ conversion rate and 99.7% selectivity for methane at 400 ^oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH₄. This work provides a new clue to fabricating efficient CO₂ conversion bimetallic materials.

Engineering Photocleavable Protein-decorated Hydrogels to Regulate Cell Adhesion and Migration

LI Tianyi, HUANG Yaying, LU Chenjing, GU Liwen, CAO Yi, YIN Sheng

2022, 38(6): 1512-1517. doi:10.1007/s40242-022-2097-7

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Cell adhesion and migration play essential roles in tissue development and maintenance, and abnormal cell migration is involved in life-threatening diseases, including vascular disease, tumor formation, and metastasis. The advances in hydrogel-based 3D cell culture development facilitated the investigation of cell motility behavior, including cell-cell and cell-matrix adhesion and cell migration in a microenvironment more related to in vivo situations. Establishing advanced methods for these in vitro studies is thus necessary. Photo-sensitive proteins show advantages in remote and non-invasive regulation of hydrogels' properties, and thus are of great potential in regulating 3D cultured cells' behavior. In the presented study, we engineered photocleavable protein(PhoCl)-decorated hydrogels to regulate cell adhesion and migration of MDA-MB-231. The integrin-binding motif RGD was fused to the PhoCl and was decorated on the hydrogel. After being exposed to light at 405 nm, the PhoCl was cleaved and the RGD motif was released, resulting in detachment of the binding cells. The regulatory effect of the light illumination showed a time-dependent and cell density-dependent manner. Furthermore, the elimination of RGD by patterned light exposure completely suspended the cell migration to the corresponding region, suggesting a controllable regulation of the cell migration direction.

Graphene Nanosheets Decorated with Copper Oxide Nanoparticles for the Photodegradation of Methylene Blue

Samavia RAFIQ, Zulfiqar Ali RAZA, Muhammad ASLAM, Muhammad Junaid BAKHTIYAR

2022, 38(6): 1518-1525. doi:10.1007/s40242-022-2109-7

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Textile industries extensively use colorants, such as methylene blue, and if disposed off untreated, they contaminate the effluent streams, causing a severe impact on the environment and aquatic life. Photocatalytic degradation has been found as an inevitable approach to treat them. Herein, we decorated the copper oxide nanoparticles on graphene nanosheets during the reflux process. The resultant copper oxide/graphene nanocomposites were analyzed for structural and functional attributes. It was observed that on increasing the copper oxide contents, the z-average size of the resultant nanocomposites decreased. The X-ray diffraction analysis demonstrated the crystalline nature of the nanocomposite. The surface morphology of the copper oxide nanoparticles appeared to be spherical and that of the copper oxide/graphene composite somehow wrinkled. The infrared analysis indicated successful intercalation of precursors in the nanocomposite. The bandgap of copper oxide/graphene nanocomposites varied in the range of 1.03-1.30 eV, which indicated their effective photocatalytic activity. The results demonstrated that after 120 min of exposure, the methylene blue removal efficiency reached 94.0%, 92.2%, and 89.4%(mass fraction) on the copper oxide/graphene nanocomposite at copper oxide nanoparticles to graphene nanosheets ratios of 1:1, 1.5:1, and 2:1 (mass ratio), respectively. The photodegradation performance of the prepared nano-catalyst was found satisfactory even after five cycles.

Asymmetric Thermally Activated Delayed Fluorescence Materials Rendering High-performance OLEDs Through both Thermal Evaporation and Solution-processing

GAO Shiyuan, CHEN Xiaojie, GE Xiangyu, CHEN Zhu, ZHAO Juan, CHI Zhenguo

2022, 38(6): 1526-1531. doi:10.1007/s40242-022-2111-0

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Exploring high-efficiency thermally activated delayed fluorescence(TADF) materials is of great importance regarding to organic light-emitting diode(OLED). Herein, we present a design strategy for developing asymmetric TADF materials based on a diphenyl sulfone-phenoxazine structure, resulting in efficient TADF emitters(CzPXZ and t-CzPXZ) with aggregation-induced emission properties, while t-CzPXZ is modified with tert-butyl groups. The two compounds exhibit high solid-state luminescence, efficient TADF, and significantly impressive device performances by both thermal evaporation and solution processing. For an instance, CzPXZ and t-CzPXZ enable the thermally-evaporated OLEDs with high external quantum efficiencies(EQEs) of over 20%. Meanwhile, t-CzPXZ allows the solution-processed device with a high EQE of 16.3% with low-efficiency roll-off, attributing to the enhanced molecular solubility and suppressed excitons quenching through tert-butyl modification on t-CzPXZ. The results reveal that the proposed asymmetric structure is a promising approach for developing high-efficiency TADF materials and OLEDs.

Removal of Anionic Dyes from Aqueous Solution with Layered Cationic Aluminum Oxyhydroxide

ZHANG Tianran, YU Huacheng, WANG Wenkai, BAI Pu, JIN Keyan, ZHANG Jia-Nan, YAN Wenfu

2022, 38(6): 1532-1541. doi:10.1007/s40242-022-2118-6

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It is highly desired yet challenged to find an adsorbent with low cost and excellent performance in the removal of organic dyes from aqueous solution. Here we reported that a layered cationic aluminum oxyhydroxide material hydrothermally synthesized from the low-cost source materials of AlCl₃∙6H₂O, CaO and H₂O, known as JU-111, can meet such criterion in removing methyl orange(MO) and Congo red(CR). JU-111 shows fast adsorption kinetics[especially for CR(15 s)] and high adsorption capacity(MO:>1000 mg/g; CR:>2900 mg/g), surpassing most of the reported adsorbents. Comprehensive characterizations of the adsorption process of MO and CR revealed that both adsorptions were achieved via the anion exchange process. The characteristics of extremely low cost and excellent performance render JU-111 great potential in the practical applications in the removal of anionic dyes.

Chelating Metal Ions in a Metal-Organic Framework for Constructing a Biomimetic Catalyst Through Post-modification

PANG Kuan, XUE Huan, LIU Haixiong, SUN Jing, LIU Tianfu

2022, 38(6): 1542-1546. doi:10.1007/s40242-022-2125-7

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Crystal engineering, as a burgeoning technology, has been widely used to construct metalloporphyrins biomimetic catalysts. Herein, a bimetallic metal-organic framework (MOF) was constructed by 4-(4-carboxyphenyl)-1,2,4-triazole ligand, Co²⁺ and Zr⁴⁺ metal ions by solvothermal reaction(named PFC-88). A N,N-chelation site was found between the two adjacent ligands in PFC-88, consequently a porphyrin-like structure was obtained through chelating Fe³⁺ in this site by post-modification, named PFC-88-Fe. The result of a single crystal X-ray technology verified that Fe ions were successfully metalated in the N,N-chelation site of PFC-88, which is assisted by the X-ray absorption near-edge structure(XANES) spectra. An o-phenylenediamine oxidation reaction was applied to assessing the catalytic activity of PFC-88-Fe, in which the absorbance increases of phenazine-2,3-diamine at λ=418 nm were recorded by absorption spectroscopy in kinetic mode, exhibiting the application potential as a biomimetic catalyst.

Insights into Promoting Effect of Sm on Catalytic Performance of the CeO₂/Beta Catalyst in Direct Conversion of Bioethanol to Propylene

JIN Huan, XU Ding, TIAN Chao, YUE Yinghong, HUA Weiming, GAO Zi

2022, 38(6): 1547-1552. doi:10.1007/s40242-022-2128-4

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Aseries of Sm-doped CeO₂/Beta composite catalysts with various Sm/Ce atomic ratios(0.1-0.4) was prepared by an incipient impregnation method, followed by calcination at 650 ^oC. They were characterized by X-ray diffraction(XRD), N₂ adsorption, X-ray photoelectron spectroscopy(XPS), Raman, NH₃-temperature programmed desorption(TPD) and CO₂-TPD. The incorporation of Sm into CeO₂/Beta increases obviously the propylene yield for the selective conversion of ethanol to propylene. The promoting effect of Sm on CeO₂/Beta can be attributed to two reasons. One is more acetone intermediates are generated on the Sm-doped catalysts due to the enhanced formation of oxygen vacancies. The other is the conversion of acetone intermediate to propylene is enhanced owing to weaker and fewer acid sites on the Sm-doped catalysts.

A Multifunctional {P₂Mo₅}-based Hybrid Applying to Catalysis, Electrocatalysis and Dye Adsorption

LIU Xiaodong, WANG Xiangchen, XU Na, ZHANG Zhong, LI Xiaohui, LIU Guocheng, WANG Xiuli

2022, 38(6): 1553-1560. doi:10.1007/s40242-022-2129-3

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As a common environmental pollutant, thioether can cause serious environmental pollution, so selective oxidation of thioether has become one of the current research hotspots. In this paper, an inorganic-organic hybrid based on a Standberg-type polyoxometalate,[Hbiz]₅[HP₂Mo₅O₂₃]·5H₂O(1)(biz=benzimidazole), was obtained by adjusting pH under hydrothermal conditions. The structure was characterized by infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Compound 1 can be used as an excellent catalyst for the oxidation of thioanisole. The experimental results showed that thioanisole could be catalytically oxidized to methyl phenyl sulfoxide by compound 1 as a catalyst within 40 min. The conversion rate and selectivity reached 99%. Compound 1 had good cycling stability as a heterogeneous catalyst. In addition, the electrocatalytic reduction of H₂O₂ and Cr₂O₇^2‒ for hybrid 1 was preliminarily investigated. In addition, the adsorption performance of hybrid 1 on cationic dye crystal violet and methylene blue was tested, and the adsorption efficiencies can reach 98.5% and 86.3%, respectively.

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