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Molten salt as ultrastrong polar solvent enables the most straightforward pyrolysis towards highly efficient and stable single-atom electrocatalyst 被引量:2
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作者 Nannan Li Wei Liu +7 位作者 Chao Zhu Ce Hao Jingya Guo Hongyu Jing Jinwen Hu Cuncun Xin Danyang Wu Yantao Shi 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第3期519-527,共9页
Currently,pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts(C-SACs),e.g.,the sintering of metal atoms at high temperature as w... Currently,pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts(C-SACs),e.g.,the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors.In this report,molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors(ionic liquid).The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization,resulting in largely enhanced yield.On the other hand,the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed.By this strategy,a C-SAC with atomically dispersed Fe-N_(4) sites and a high specific area over 2000 m^(2) g^(-1) is obtained,which illustrates high ORR activity in both acid and alkaline media.Moreover,this SAC exhibits superior methanol tolerance and stability after acid soaking at 85℃ for 48 h.It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs,but also can be extended to prepare other types of SACs. 展开更多
关键词 Ultrastrong polar solvent Molten salts one-pot pyrolysis Carbon-supported single atom catalysts Oxygen reduction reaction
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Enhancing lead-free photovoltaic performance:Minimizing buried surface voids in tin perovskite films through weakly polar solvent pre-treatment strategy
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作者 Dongdong Yan Han Zhang +7 位作者 Chensi Gong Hailong Wang Qing Lu Jun Liu Wenzhen Lv Mingguang Li Runfeng Chen Ligang Xu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第11期556-561,共6页
Buried interfacial voids have always been a notorious phenomenon observed in the fabrication of lead perovskite films. The existence of interfacial voids at the buried interface will capture the carrier, suppress carr... Buried interfacial voids have always been a notorious phenomenon observed in the fabrication of lead perovskite films. The existence of interfacial voids at the buried interface will capture the carrier, suppress carrier transport efficiencies, and affect the stability of photovoltaic devices. However, the impact of these buried interfacial voids on tin perovskites, a promising avenue for advancing lead-free photovoltaics, has been largely overlooked. Here, we utilize an innovative weakly polar solvent pretreatment strategy(WPSPS) to mitigate buried interfacial voids of tin perovskites. Our investigation reveals the presence of numerous voids in tin perovskites during annealing, attributed to trapped dimethyl sulfoxide(DMSO) used in film formation. The WPSPS method facilitates accelerated DMSO evaporation, effectively reducing residual DMSO. Interestingly, the WPSPS shifts the energy level of PEDOT:PSS downward, making it more aligned with the perovskite. This alignment enhances the efficiency of charge carrier transport. As the result, tin perovskite film quality is significantly improved,achieving a maximum power conversion efficiency approaching 12% with only an 8.3% efficiency loss after 1700 h of stability tests, which compares well with the state-of-the-art stability of tin-based perovskite solar cells. 展开更多
关键词 Tin perovskite Buried interfacial Weakly polar solvent pre-treatment strategy
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Non-polar Solvent Microwave-Assisted Extraction of Volatile Constituents from Dried Zingiber Officinale Rosc. 被引量:2
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作者 于永 汪子明 +4 位作者 王玉堂 李铁纯 程建华 刘忠英 张寒琦 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2007年第3期346-350,共5页
A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcar... A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcarbonyl iron powders (CIP) into extraction system, the essential oil was extracted by the non-polar solvent (ether) which can be heated by CIP. The constituents of essential oil obtained by NPSMAE were comparable with those obtained by hydrodistillation (HD) by GC-MS analysis, which indicates that NPSMAE is a feasible way to extract essential oil from dried plant materials. The NPSMAE took much less extraction time (5 min) than HD (180 min), and its extraction efficiency was much higher than that of conventional polar solvent microwave-assisted extraction (PSMAE) and mixed solvent microwave-assisted extraction (MSMAE). It can be a good alternative for the extraction of volatile constituents from dried plant samples. 展开更多
关键词 non-polar solvent microwave-assisted extraction Zingiber officinale Rosc. essential oil carbonyl iron powder
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Influence of Self-Assembly and Solvent Polarity on Fluorescence Properties of Hydrophobic Organic Cations Based on Anthracene Skeleton 被引量:1
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作者 TAN Chunxia 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2019年第3期238-244,共7页
Fluorescence mode is influenced by the substituents, the polarity of the solvent, the steric factor and even the aggregation state of molecules in solvent under the testing environment. By comparing the fluorescent be... Fluorescence mode is influenced by the substituents, the polarity of the solvent, the steric factor and even the aggregation state of molecules in solvent under the testing environment. By comparing the fluorescent behavior of three anthracene derivatives, we observe that the hydrophobic interaction and steric effect in structures reduce fluorescence intensity, quantum yield and fluorescence lifetime. The emitting mode of two amphiphilic salts changes from aggregation emission in weak polar solvent to monomer emission in strong polar solvent and gives the similar variety in mixed solvent. 展开更多
关键词 organic CATIONS FLUORESCENCE SELF-ASSEMBLY solvent polarity MONOMER EMISSION aggregation EMISSION
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Effects of Hydrogen-bonding Interaction and Polarity on Emission Spectrum of Naphthalene-Triethylamine in Mixed Solvent
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作者 Yoshimi Sueishi Shunzo Yamamoto 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2004年第5期606-611,共6页
The effects of the protic and aprotic polar solvents on the emission spectrum of the naphthalene-triethyl-amine system in THF were studied under conditions of steady-state illumination. The fluorescence spectrum of th... The effects of the protic and aprotic polar solvents on the emission spectrum of the naphthalene-triethyl-amine system in THF were studied under conditions of steady-state illumination. The fluorescence spectrum of the naphthalene-triethylamine system consists of two emission bands, the fluorescence band of naphthalene(band A, 329 nm) and the emission band of the exciplex(band B, 468 nm). The intensities of both the emission bands decrease with increasing the solvent polarity. The intensity of band B also decreases due to the hydrogen-bonding interaction between triethylamine and protic solvent, while that of band A increases. It is thus suggested that the quenching of naphthalene fluorescence by triethylamine in THF occurs through the charge transfer and electron transfer reactions. The spectral changes upon the increase of solvent polarity can be explained by the dependences of the equilibrium constant between exciplex and ion-pair and the rate constant for the electron transfer reaction from triethylamine to the excited naphthalene on the relative permittivity of solvent. It is shown that the formation of intermolecular hydrogen-bonding between triethylamine and protic solvent suppresses the quenching reaction by the decrease in free amine. Acetonitrile has only a polar effect and trichloroacetic acid only a hydrogen-bonding(or protonation) effect, while alcohols have both the effects. The effects of alcohols could be separated into the effects of solvent polarity and intermolecular hydrogen-bonding interaction quantitatively. 展开更多
关键词 Naphthalene-triethylamine Fluorescence spectrum solvent effect solvent polarity Hydrogen-bonding interaction.
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Effects of Polar Organic Solvent on Separation of Y(edta)^-/Nd(edta)^- Complexes on Polyacrylic Anion Exchangers
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作者 Halina Hubicka Dorota Kolodynska 《Journal of Rare Earths》 SCIE EI CAS CSCD 2005年第1期124-128,共5页
The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exc... The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H_2O-methanol and H_2O-ethanol systems. In most cases the determined distribution coefficients of Ln^(3+) complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water (media.) 展开更多
关键词 polar organic solvent Y(edta)^-/Nd(edta)^- separation ion exchange rare earths
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Effect of Solvent Polarity on Excited-State Double Proton Transfer Process of 1,5-Dihydroxyanthraquinone
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作者 Zheng-Ran Wang Li-Xia Zhu +7 位作者 Xing-Lei Zhang Bo Li Yu-Liang Liu Yong-Feng Wan Qi Li Yu Wan Hang Yin Ying Shi 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第2期289-294,I0002,共7页
The excited-state double proton transfer(ESDPT)properties of 1,5-dihydroxyanthraquinone(1,5-DHAQ)in various solvents were investigated using femtosecond transient absorption spectroscopy and the DFT/TDDFT method.The s... The excited-state double proton transfer(ESDPT)properties of 1,5-dihydroxyanthraquinone(1,5-DHAQ)in various solvents were investigated using femtosecond transient absorption spectroscopy and the DFT/TDDFT method.The steady-state fluorescence spectra in toluene,tetrahydrofuran(THF)and acetonitrile(ACN)solvents presented that the solvent polarity has an effect on the position of the ESDPT fluorescence emission peak for the 1,5-DHAQ system.Transient absorption spectra show that the increasing polarity of the solvent accelerates the rate of excited state dynamics.Calculated potential energy curves analysis further verified the experimental results.The ESDPT barrier decreases gradually with the increase of solvent polarity from toluene,THF to ACN solvent.It is convinced that the increase of solvent polarity can promote the occurrence of the ESDPT dynamic processes for the 1,5-DHAQ system.This work clarifies the mechanism of the influence of solvent polarity on the ESDPT process of 1,5-DHAQ,which provides novel ideas for design and synthesis of new hydroxyanthraquinone derivatives. 展开更多
关键词 Density functional theory Time-dependent density functional theory Femtosecond transient absorption spectrum solvent polarity Excited-state double proton transfer Hydroxyanthraquinone compound
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Propylene Polymerization Catalyzed by Bis(R_3-indenyl) Zirconium Bichloride/Aluminoxane──Synthesis of Metallocenes and Influence ofSolvent Polarity on Polymerization
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作者 YASIN Tariq FAN Zhi-qiang +1 位作者 ZHU Yin-bang FENG Lin-xian 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2001年第4期445-451,共7页
Three unbridged metallocenes, bis(2,4,7-Me3-indenyl)zirconium dichloride(1) , bis(2-Me-4, 7-Et2-indenyl)zirconium dichloride (2) and bis (2, 4, 6-Me3-indenyl) zirconium dichloride (3) were synthesized. The effect of s... Three unbridged metallocenes, bis(2,4,7-Me3-indenyl)zirconium dichloride(1) , bis(2-Me-4, 7-Et2-indenyl)zirconium dichloride (2) and bis (2, 4, 6-Me3-indenyl) zirconium dichloride (3) were synthesized. The effect of solvent polarity on propylene polymerization catalyzed by the metallocenes in the presence of methylaluminoxane(MAO) and triisobutylaluminum(TIBA) was investigated in the toluene/CH2Cl2 mixed solvent. Changing the solvent polarity was found to influence the catalytic activity, polymer molecular weight and stereospecificity of the catalysts. The changes in the position of the substituents on the ligand caused the different responses of the catalyst to the changes in solvent polarity. The isotactic stereosequence of polypropylene was found to increase with the increase in the polarity of the reaction medium. 展开更多
关键词 Propylene polymerization Metallocene catalyst solvent effect polarity
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Electron transport in solution-grown TIPS-pentacene single crystals:Effects of gate dielectrics and polar impurities
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作者 Zhuo-Ting Huang Guo-Biao Xue +7 位作者 Jia-Ke Wu Shuang Liu Huan-Bin Li Yu-Hui Yang Feng Yan Paddy K.L.Chan Hong-Zheng Chen Han-Ying Li 《Chinese Chemical Letters》 SCIE CAS CSCD 2016年第12期1781-1787,共7页
The n-channel behavior has been occasionally reported in the organic field-effect transistors (OFETs) that usually exhibit p-channel transport only. Reconfirmation and further examination of these unusual device per... The n-channel behavior has been occasionally reported in the organic field-effect transistors (OFETs) that usually exhibit p-channel transport only. Reconfirmation and further examination of these unusual device performances should deepen the understanding on the electron transport in organic semiconductors. 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene), a widely examined p-channel material as Au is used for source-drain electrodes, has recently been reported to exhibit electron transport when grown from non-polar solvent on divinyltetramethyldisiloxanebis (benzocy- clobutene) (BCB) dielectric, spurring the study on this unusual electron transport. This paper describes FET characteristics of solution-grown TlPS-pentacene single crystals on five polymer gate dielectrics including polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(4-vinyl phenol) (PVP), poly(vinyl alcohol) (PVA) and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)). In addition to the p-channel behavior, electron transport occurs in the crystals on PMMA, PS, thick PVA (40 nm) and a bilayer dielectric of PMMA on P(VDF-TrFE-CFE), while does not on PVP and thin PVA (2 nm). The two distinct FET characteristics are consistent with the previous reported trap effect of hydroxyl groups (in PVP and PVA) and reduced injection barrier by Na~ ions (as impurity in PVA). The highest electron mobility of 0.48 cm2 V-1 s-1 has been achieved in the crystals on PMMA. Furthermore, the electron transport is greatly attenuated after the crystals are exposed to the vapor of a variety of polar solvents and the attenuated electron transport partially recovers if the crystals are heated, indicating the adverse effect of polar impurities on electron transport. By reconfirming the n-channel behavior in the OFETs based on TIPS-pentacene, this work has implications for the design of n-channel and ambipolar OFETs. 展开更多
关键词 TIPS-pentacene single crystal Electron transport Polymer dielectric polar solvent Organic field-effect transistor
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Solvent Effects on Spectral Property and Dipole Moment of the Lowest Excited State of Coumarin 343 Dye 被引量:1
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作者 Li-lin Jiang Wei-long Liu +4 位作者 Yun-fei Song Xing He Yang Wang Hong-lin Wu Yan-qiang Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第5期577-584,I0004,共9页
Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 (C343) were measured in different solvents. The effect of the solvent on the spectral properties and dipole mo... Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 (C343) were measured in different solvents. The effect of the solvent on the spectral properties and dipole moment of the lowest excited state of C343 were investigated. It was found that the absorption and fluorescence spectra red-shifted slightly and strongly with increasing solvent polarity, respectively, because the charge distribution of the excited state leaded to the increasing difference between the absorption and fluorescence spectra with increasing solvent polarity. The dipole moment of the lowest excited state of C343 was determined from solvatochromic measurements and the quantum chemical calculation, and the results obtained from these two methods were fully consistent. Investigations of the time-resolved fluorescence of C343 in different solvents indicated that the fluorescence lifetimes increased nearly linearly with 4.45 ns in water. This can be ascribed between C343 and hydrogen donating increasing solvent polarity from 3.09 ns in toluene to to the intermolecular hydrogen bonding interactions solvents 展开更多
关键词 Time-resolved fluorescence Dipole moment solvent polarity function Quan-tum chemical calculation Intermolecular hydrogen bonding interaction
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Ca-alginate spheres behavior in presence of some solvents and water-solvent mixtures 被引量:1
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作者 Luis G. Torres Angelica Velasquez Marco A. Brito-Arias 《Advances in Bioscience and Biotechnology》 2011年第1期8-12,共5页
Immobilization systems more frequently used are calcium alginate spheres. These biocatalysts have many potential applications in the immobilization of enzymes, prokaryotic cells, vegetal and animal cells, algae, organ... Immobilization systems more frequently used are calcium alginate spheres. These biocatalysts have many potential applications in the immobilization of enzymes, prokaryotic cells, vegetal and animal cells, algae, organelles and mixtures of these living components. Other applications of immobilized cells imply the use of non aqueous systems. Some bioconversions are carried out in the presence of solvents such as hexane acetone or acetonitrile, or mixtures water-solvents. The aim of this work was to investigate the behaviour of Ca-alginate spheres when put in contact with different solvents (water, diesel, ethanol, methanol, acetone, n-hexane, isopropyl alcohol, THF, acetonitrile, and toluene), or solvent-water mixtures (i.e., ethanol-water), regarding the resistance of the alginate spheres after days of contact. Calcium alginate particles suffered different damages, depending on the solvent they were put in contact. Water did not damaged the Ca-alginate structure with or without Ca present. On the other hand different solvents lost a proportion of volume, i.e., n-hexane (16%), methanol (19%), ethanol (19.5%), toluene (22%), diesel (34%), acetone (765), isopropyl alcohol (80%), THF and acetonitrile (total loss, total destruction). Nor the dielectric constant nor the polarity indexes were capable of explaining the difference on the volume loss or total sphere destruction, except for water-ethanol mixtures. 展开更多
关键词 DIELECTRIC CONSTANT CA-ALGINATE IMMOBILIZATION solvents SPHERES polarity INDEX
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退役锂电池正极材料多离子体系的水基低共熔溶剂浸出
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作者 何玲 张建磊 +3 位作者 董其铮 候显 李子轩 李文生 《中国有色金属学报》 北大核心 2025年第6期2103-2111,共9页
为高效分离退役锂电池正极材料多离子体系中的铝元素,分析了以柠檬酸(CA)和乙二醇(EG)为主要成分的水基低共熔溶剂对退役锂电池正极材料的多离子体系浸出及分离过程。利用该溶剂良好的体系稳定性和优异的浸出性能,研究不同极性水基低共... 为高效分离退役锂电池正极材料多离子体系中的铝元素,分析了以柠檬酸(CA)和乙二醇(EG)为主要成分的水基低共熔溶剂对退役锂电池正极材料的多离子体系浸出及分离过程。利用该溶剂良好的体系稳定性和优异的浸出性能,研究不同极性水基低共熔溶剂对各金属元素浸出率的影响。结果表明:最佳浸出条件为n(EG)∶n(CA)=1.5∶1,浸出温度为90℃,浸出时间为1 h,固液比(g/mL)为3∶100;在最佳条件下,Al、Co、Fe、Li、Mn和Ni的浸出率分别为6.55%、99.26%、90.23%、95.22%、83.77%和95.71%。该柠檬酸/乙二醇水基低共熔溶剂无需额外添加还原剂即可实现高效浸出,成功分离了多离子正极材料中的Al、Co、Fe、Li、Mn和Ni等金属元素,尤其是对Al元素的选择性分离展现出显著优势。 展开更多
关键词 柠檬酸 乙二醇 水基低共熔溶剂 极性 多离子正极材料 酸浸
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极性溶剂掺杂和后处理协同改善PEDOT:PSS电极及其在PeLEDs中的应用 被引量:1
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作者 袁俊钊 刘国栋 +2 位作者 吴俊凯 王要李 陶梦欣 《印刷与数字媒体技术研究》 北大核心 2025年第1期154-162,共9页
聚(3,4-乙烯二氧噻吩):聚苯乙烯磺酸盐(PEDOT:PSS)作为高导电率、高光透过率的电极材料引起了业界的广泛关注。本研究通过极性溶剂掺杂和后处理协同改善的方式对PEDOT:PSS进行材料改性,研究了甲酰胺(FA)、二甲基亚砜(DMSO)和N,N-二甲基... 聚(3,4-乙烯二氧噻吩):聚苯乙烯磺酸盐(PEDOT:PSS)作为高导电率、高光透过率的电极材料引起了业界的广泛关注。本研究通过极性溶剂掺杂和后处理协同改善的方式对PEDOT:PSS进行材料改性,研究了甲酰胺(FA)、二甲基亚砜(DMSO)和N,N-二甲基甲酰胺(DMF)三种极性不同的溶剂掺杂、后处理以及薄膜厚度对薄膜电导率、光透过率及薄膜均匀性的影响。研究表明,FA掺杂增强了PEDOT:PSS在溶剂中的分散,提高了成膜均匀性。在最佳成膜厚度条件下,FA掺杂、后处理的薄膜达到电导率1084.5S/cm、光透过率91.86%的最佳性能。基于钙钛矿发光二极管(PeLEDs)的原理,本研究以最佳PEDOT:PSS电极薄膜为底部阳极,制备了PeLEDs器件。该器件最大亮度为3246.5cd/m2,最大电流效率为5.46cd/A,表明所制备的PEDOT:PSS电极薄膜在钙钛矿光电器件领域具有显著的应用潜力。 展开更多
关键词 极性溶剂 协同改善 PEDOT:PSS 钙钛矿发光二极管
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[Emim]Ac-[Emim]OH-DMSO三元体系溶解纤维素的研究
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作者 张晓钰 兰金鑫 +3 位作者 黎昕 曹石林 高海丽 马晓娟 《化工学报》 北大核心 2025年第7期3226-3234,共9页
离子液体1-乙基-3-甲基氢氧化咪唑([Emim]OH)是一种极具潜力的纤维素溶剂,但是因其结构不稳定限制了进一步的应用。为了提高[Emim]OH的稳定性,通过密度泛函理论(DFT)计算以及实验选择合适的极性非质子溶剂二甲基亚砜(DMSO),构建1-乙基-3... 离子液体1-乙基-3-甲基氢氧化咪唑([Emim]OH)是一种极具潜力的纤维素溶剂,但是因其结构不稳定限制了进一步的应用。为了提高[Emim]OH的稳定性,通过密度泛函理论(DFT)计算以及实验选择合适的极性非质子溶剂二甲基亚砜(DMSO),构建1-乙基-3-甲基醋酸咪唑([Emim]Ac)-[Emim]OH-DMSO三元体系稳定氢氧盐离子液体且提高其对纤维素的溶解能力。研究结果表明,离子液体与DMSO摩尔比为1.25∶0.75且[Emim]Ac与[Emim]OH摩尔比为2∶1时,竹浆在三元溶剂体系中的溶解度达9.9%,比在纯[Emim]Ac中的溶解度提高了23.8%。经三元溶剂体系溶解再生后,纤维素聚合度从523下降至466,纤维素的晶型由Ⅰ型变为Ⅱ型。DMSO的加入不仅降低了混合离子液体体系黏度,黏度从21.2 Pa·s下降至19.7 Pa·s,还加快了纤维素的溶解。 展开更多
关键词 离子液体 纤维素 DFT 极性非质子溶剂 溶解
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绿色溶剂体系中纤维素催化转化制备5-HMF
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作者 罗丽萍 沈娅楠 +3 位作者 史欣怡 王紫怡 季赵天 卿青 《现代化工》 北大核心 2025年第11期126-132,共7页
玉米秸秆经丙酮预处理提取富含纤维素的固体原料,经高温高压反应釜“一锅法”制备5-羟甲基糠醛(5-HMF)。以纤维素转化率、反应选择性和5-HMF产率为指标,考察了路易斯酸和布朗斯特酸催化剂种类、有机溶剂种类及配比、底物浓度、催化剂用... 玉米秸秆经丙酮预处理提取富含纤维素的固体原料,经高温高压反应釜“一锅法”制备5-羟甲基糠醛(5-HMF)。以纤维素转化率、反应选择性和5-HMF产率为指标,考察了路易斯酸和布朗斯特酸催化剂种类、有机溶剂种类及配比、底物浓度、催化剂用量、反应温度和时间等因素对催化反应的影响,并通过FT-IR、XRD、FE-SEM等表征手段,对不同反应阶段的固体样品进行分析,辅助揭示催化反应机制。研究结果表明,以适量的布朗斯特酸与路易斯酸催化剂复配能够有效提高5-HMF的产率,过量的催化剂、过高的反应温度和过长的催化反应时间均会导致反应体系中副产物的增多,从而造成5-HMF产率的下降。确定的最佳工艺条件为:采用30 mL的四氢呋喃(THF)/水(5∶1)混合溶剂体系,在5%的底物浓度下,以AlCl_(3)·6H_(2)O(与底物质量比为1∶6)和草酸(用量为0.4%)联合催化,在170℃下反应40 min,反应体系纤维素转化达到95.4%,反应选择性为52.3%,5-HMF产率达到49.9%。 展开更多
关键词 纤维素 极性非质子溶剂 金属氯化物 草酸 5-HMF
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4′-N,N-二乙氨基-3-羟基苯并黄酮激发态分子内质子转移机制的溶剂极性效应——实验和理论研究
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作者 姜羊林 陈明卿 +4 位作者 梁民 尧奕歌 张燕 王鹏 张建平 《物理化学学报》 北大核心 2025年第2期116-124,共9页
激发态分子内质子转移(ESIPT)反应是一种重要的基础光化学反应,通常发生在具有分子内氢键的发色团中。3-羟基黄酮类衍生物(3-HFs)由于其广泛的天然来源和对环境极度敏感的荧光发光特性而备受关注。与3-HFs相比,4′-N,N-二乙氨基-3-羟基... 激发态分子内质子转移(ESIPT)反应是一种重要的基础光化学反应,通常发生在具有分子内氢键的发色团中。3-羟基黄酮类衍生物(3-HFs)由于其广泛的天然来源和对环境极度敏感的荧光发光特性而备受关注。与3-HFs相比,4′-N,N-二乙氨基-3-羟基黄酮(D-HBF)具有扩展的共轭体系和大幅红移的吸收特性,而最新研究表明,由于具有ESIPT特性,它可以用作环境极性敏感的生物荧光探针。本研究通过采用多种光谱和理论计算方法,系统研究了D-HBF在极性不同的三种非质子型溶剂(环己烷、乙醚和四氢呋喃)中的ESIPT反应机制。研究结果显示,在这三种溶剂中均能观测到D-HBF的ESIPT典型双发射峰,而这些峰的相对比率受溶剂极性的调控。荧光动力学分析揭示,随着溶剂极性的增加,激发态中正向和反向的质子转移反应速率都降低,同时反向质子转移变得更占优势。该研究还通过密度泛函理论和含时密度泛函理论计算,比较了三种溶剂中D-HBF的基态和激发态分子内氢键的键长和键角参数,确定了ESIPT反应是激发态分子内氢键增强机制。计算结果表明,增加溶剂极性会导致处于S1态的D-HBF分子的3-羟基伸缩振动红外吸收频率向高波数移动,这证明了相应的N^(*)态的分子内氢键减弱。此外,电子密度分析显示,引入在4′-位的强给电子官能团(4′-N,N-二乙氨基)使得D-HBF在激发态下具有典型的分子内电荷转移特征。最后,势能曲线计算结果表明,在激发态下质子转移更容易发生,而溶剂极性增加会导致更高的质子转移势垒,从而阻碍了相应的ESIPT反应。吉布斯自由能分析进一步表明,溶剂极性增加使激发态快速质子转移更倾向于向N^(*)态移动。这项研究为D-HBF类衍生物作为环境极性敏感的生物探针的应用提供了理论基础。 展开更多
关键词 4′-N N-二乙氨基-3-羟基苯并黄酮 激发态分子内质子转移 密度泛函理论/含时密度泛函理论 溶剂极性效应 荧光动力学
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不同品种核桃内种皮极性提取物抗氧化活性的比较
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作者 丁真真 刘艳全 +4 位作者 张甜 姜蕾 夏娜 阿里旦·阿力木 张超 《食品研究与开发》 2025年第8期63-70,79,共9页
为深入挖掘提取相与不同品种核桃内种皮的活性成分和抗氧化性能之间的关联性。以5种不同品种的核桃内种皮为材料,对其乙醇相、乙酸乙酯相、纤维素酶相、正丁醇和水相提取物的总酚、总黄酮含量,以及DPPH自由基、ABTS+自由基、羟基自由基... 为深入挖掘提取相与不同品种核桃内种皮的活性成分和抗氧化性能之间的关联性。以5种不同品种的核桃内种皮为材料,对其乙醇相、乙酸乙酯相、纤维素酶相、正丁醇和水相提取物的总酚、总黄酮含量,以及DPPH自由基、ABTS+自由基、羟基自由基清除率和还原力等指标进行系统研究与比较。结果表明,提取相的选择对核桃内种皮的活性成分和抗氧化性能影响显著。在活性成分提取方面,乙醇作为提取剂优势突出,其中‘扎343’核桃内种皮乙醇相提取物的总酚、总黄酮含量在各品种中最高,分别达到747.24 mg GAE/g和54.31 mg RE/g。不同品种的核桃抗氧化能力呈现出显著差异,在质量浓度为0.20 mg/mL的条件下,‘新新2’乙醇相提取物对DPPH自由基的清除率高,达84.83%‘;温185’乙酸乙酯相提取物对?OH的清除率最高,达到94.24%;相关性分析显示,核桃内种皮的活性成分与抗氧化能力之间存在紧密联系,但不同品种中各抗氧化指标与总酚、总黄酮含量的相关性呈现出不一致的趋势。 展开更多
关键词 核桃 内种皮 不同极性溶剂 抗氧化活性 相关性分析
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基于极性溶剂物理信息的溶剂安全鉴别方法研究
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作者 张军军 吴云波 杨园 《山西化工》 2025年第10期174-175,195,共3页
为实现对极性溶剂的物理信号安全鉴别,研究提出了一种基于支持向量机和随机森林的溶剂安全鉴别方法,该方法使用支持向量机和随机森林对极性溶剂的电信号进行鉴别以此实现对溶剂安全性的分析。研究结果表明,30%浓度的乙醇溶液的电压信号... 为实现对极性溶剂的物理信号安全鉴别,研究提出了一种基于支持向量机和随机森林的溶剂安全鉴别方法,该方法使用支持向量机和随机森林对极性溶剂的电信号进行鉴别以此实现对溶剂安全性的分析。研究结果表明,30%浓度的乙醇溶液的电压信号最高能够达到60 V。新模型的鉴别准确率最高能够达到0.99,相较于随机森林模型提高0.21。可见使用新模型能够更加准确地对极性溶剂进行鉴别,以此分析鉴别不同溶剂的安全性。研究对极性溶剂的安全鉴别具有很好的指导意义。 展开更多
关键词 极性溶剂 电信号 SVM RF
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基于不同极性溶剂的亚麻叶萃取物含量、抗氧化活性及其关联性研究
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作者 赵爱萍 辛敏 +7 位作者 胡润红 石福祥 鲁瑜萍 郭艺菲 陶梁春 陈延 张育凤 马虹 《药学前沿》 2025年第10期1651-1658,共8页
目的 系统评价亚麻叶不同极性溶剂萃取物中5种主要活性成分的含量、总黄酮含量及其体外抗氧化活性,并深入分析其相关性。方法 采用HPLC法测定绿原酸、异荭草素、荭草素、牡荆素、异牡荆素5种成分的含量;以芦丁为对照品,采用氯化铝比色... 目的 系统评价亚麻叶不同极性溶剂萃取物中5种主要活性成分的含量、总黄酮含量及其体外抗氧化活性,并深入分析其相关性。方法 采用HPLC法测定绿原酸、异荭草素、荭草素、牡荆素、异牡荆素5种成分的含量;以芦丁为对照品,采用氯化铝比色法测定总黄酮含量;综合运用DPPH法、ABTS^(+)法和Cu^(2+)还原能力法全面评估其抗氧化活性。结果 乙酸乙酯与正丁醇萃取物中5种成分及总黄酮含量较高,抗氧化活性相对较强。乙酸乙酯萃取物中绿原酸、异荭草素、荭草素、牡荆素、异牡荆素和总黄酮含量分别为4.35%±0.03%、19.19%±0.21%、8.13%±0.09%、1.65%±0.03%、1.07%±0.01%、58.26%±0.35%。其DPPH、ABTS^(+)和Cu^(2+)还原能力的半抑制浓度分别为7.4、6.6、25.7μg/mL。正丁醇萃取物中各成分含量及抗氧化活性次之。各指标由高到低(或活性由强到弱)的次序一致,均为:乙酸乙酯萃取物>正丁醇萃取物>萃余相浓缩物>石油醚萃取物。相关性分析进一步证实,5种成分及总黄酮含量与3种抗氧化活性指标间均存在显著或极显著正相关。结论 乙酸乙酯和正丁醇萃取物是亚麻叶抗氧化活性的主要物质基础,其中特定成分含量与活性强度显著相关。该研究为亚麻叶作为天然抗氧化剂在相关领域的开发与应用提供了科学依据。 展开更多
关键词 亚麻叶 不同极性溶剂萃取物 绿原酸 异荭草素 荭草素 牡荆素 异牡荆素 总黄酮 含量 抗氧化活性 相关性
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3-三氟甲基吡啶制备方法研究
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作者 马亚锋 魏攀 +1 位作者 杨文龙 白红杰 《有机氟工业》 2025年第4期6-9,共4页
提供了一种3-三氟甲基吡啶(3-TF)的制备方法,将3-甲基吡啶(3MP)和极性非质子溶剂(二乙二醇二甲醚)按比例混合后通入微通道反应器中,与氟/氮混合气进行反应,此反应为放热反应,过程控制温度、压力、物料停留时间,生成产物3-三氟甲基吡啶... 提供了一种3-三氟甲基吡啶(3-TF)的制备方法,将3-甲基吡啶(3MP)和极性非质子溶剂(二乙二醇二甲醚)按比例混合后通入微通道反应器中,与氟/氮混合气进行反应,此反应为放热反应,过程控制温度、压力、物料停留时间,生成产物3-三氟甲基吡啶。反应后物料通过三级减压精馏工艺,第一级塔顶得到质量分数≥99%的目标产物3-TF,第二级塔顶、第三级塔顶分别回收未反应完全的3MP和溶剂,循环再利用。 展开更多
关键词 3-甲基吡啶 极性非质子溶剂 氟/氮混合气 3-三氟甲基吡啶 微通道反应器
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