CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Jianqiang Zhang,Yongsheng Peng,Wenguang Leng,Yanan Gao,Feifei Xu,Jinling Chai
We introduced bipyridine ligands into a series of two-dimensional (2D) covalent organic frameworks (COFs) using 2,2′-bipyridine-5,5′-dicarbaldehyde (2,2′-BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2′-BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyridine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be varied, with one ligand favoring binding in the space between adjacent COFs′ layers and the other ligand favoring binding within the pores of the COFs. The Pd(II)-loaded COFs exhibited good catalytic activity for the Heck reaction.
✓ 已验证
产品关联
DOI
高影响因子
PEDOSPHERE
·
2017
·
IF 1.734
Jiajun DENG,Yanling ZHANG,Jiwei HU,Jiaguo JIAO,Feng HU,Huixin LI,Shixiang ZHANG
Autotoxicity is one of the major factors that impede continuous cropping. It is defined as the toxic influence of chemicals released from one plant species on the germination and growth of individuals of the same species. Here, in order to exam the autotoxicity of tobacco root exudates, root exudates were collected from tobacco plants grown both in cultural solution and on natural soil. Using ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry, main autotoxic chemical substances in the root exudates were identified. The autotoxic effects of suspected autotoxins on seed germination (including germination rate, germination potential, germination index, and vigor index) and seedling growth were analyzed. Dibutyl phthalate (or diisobutyl phthalate), dioctyl phthalate, and diisooctyl phthalate were identified in tobacco root exudates. It was observed that high concentrations (greater than 0.5 mmol L −1 ) of each identified phthalate ester caused significant ( P < 0.05) inhibition of tobacco seed germination and seedling growth. It can be concluded that phthalate esters such as dibutyl phthalate, diisobutyl phthalate, and diisooctyl phthalate in tobacco root exudates may play an important role in tobacco autotoxicity.
✓ 已验证
产品关联
DOI
高影响因子
Chinese Physics B
·
2017
·Vol. 26
·期 6
·067804
·
IF 1.223
Qi Ding,Xiao-Song Zhang,Lan Li,Jian-Ping Xu,Ping Zhou,Xiao-Fei Dong,Ming Yan
Colloidal ZnAgInSe (ZAISe) quantum dots (QDs) with different particle sizes were obtained by accommodating the reaction time. In the previous research, photoluminescence (PL) of ZAISe QDs only could be tuned by changing the composition. In this work the size-tunable photoluminescence was observed successfully. The red shift in the photoluminescence spectra was caused by the quantum confinement effect. The time-resolved photoluminescence indicated that the luminescence mechanisms of the ZAISe QDs were contributed by three recombination processes. Furthermore, the temperature-dependent PL spectra were investigated. We verified the regular change of temperature-dependent PL intensity, peak energy, and the emission linewidth of broadening for ZAISe QDs. According to these fitting data, the activation energy (ΔE) of ZAISe QDs with different nanocrystal sizes was obtained and the stability of luminescence was discussed.
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Dun Deng,Yun Zhang,Aijun Sun,Yunfeng Hu
We previously functionally characterized a novel marine microbial GDSL lipase MT6 and identified that the stereo-selectivity of MT6 was opposite to that of other common lipases in trans-esterification reactions. Herein, we have investigated the use of MT6 in stereo-selective biocatalysis through direct hydrolysis reactions. Notably, the stereo-selectivity of MT6 was also demonstrated to be opposite to that of other common lipases in hydrolysis reactions. Parameters, including temperature, organic co-solvents, pH, ionic strength, catalyst loading, substrate concentration, and reaction time, affecting the enzymatic resolution of racemic 1-phenylethyl acetate were further investigated, with the e.e. of the final ( S )-1-Phenylethanol product and the conversion being 97% and 28.5%, respectively, after process optimization. The lengths of side chains of 1-phenylethyl esters greatly affected the stereo-selectivity and conversion during kinetic resolutions. MT6 is a novel marine microbial GDSL lipase exhibiting opposite stereo-selectivities than other common lipases in both trans-esterification reactions and hydrolysis reactions.
✓ 已验证
产品关联
DOI
高影响因子
Materials Research Express
·
2016
·Vol. 3
·期 6
·065018
·
IF 0.968
Pinhua Zhang,Guangliang Cui,Chuanhai Xiao,Mingzhe Zhang,Li Chen,Changmin Shi
We fabricated an Ag decorated Cu (Ag@Cu) nano/microstructure ordered array by facile template-free 2D electrodeposition combined with a galvanic reduction method for SERS applications. The Cu nano/microstructure ordered arrays were first synthesized by a 2D electrodeposition method, then Ag nanocubes were decorated on the arrays by galvanic reduction without any capping agent. The pollution-free surface and edge-to-face heterostructure of Ag nanocubes and Cu nano/microstructure arrays provide the powerful field-enhancements for SERS performance. The results verified that the Ag@Cu nano/microstructure ordered arrays have excellent activity for 4-Mercaptopyridine, and the sensitivity limit is as low as 10−8 M. Therefore, this facile route provides a useful platform for the fabrication of a SERS substrate based on nano/microstructure ordered arrays.
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Qi Sun,Xianglan Xu,Honggen Peng,Xiuzhong Fang,Wenming Liu,Jiawei Ying,Fan Yu,Xiang Wang
A series of SnO 2 -based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M (M = Mn, Zr, Ti and Pb) molar ratio of 9/1 were prepared by a co-precipitation method and used for CH 4 and CO oxidation . The Mn 3+ , Zr 4+ , Ti 4+ and Pb 4+ cations are incorporated into the lattice of tetragonal rutile SnO 2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO 2 . Using an X-ray diffraction extrapolation method, the lattice capacity of SnO 2 for Mn 2 O 3 was 0.135 g Mn 2 O 3 /g SnO 2 , which indicates that to form stable solid solution, only 21% Sn 4+ cations in the lattice can be maximally replaced by Mn 3+ . If the amount of Mn 3+ cations is over the capacity, Mn 2 O 3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn-Mn solid solution phase show higher activity than the ones with excess Mn 2 O 3 species.
✓ 已验证
产品关联
DOI
高影响因子
Chinese Journal of Natural Medicines
·
2016
·
IF 1.382
Zhuo-Wei SHEN,Meng-Yue LUO,Hai-Hong HU,Hui ZHOU,Hui-Di JIANG,Lu-Shan YU,Su ZENG
NTCP is specifically expressed on the basolateral membrane of hepatocytes, participating in the enterohepatic circulation of bile salts, especially conjugated bile salts, to maintain bile salts homeostasis. In addition, recent studies have found that NTCP is a functional receptor of HBV and HDV. Therefore, it is important to study the interaction between drugs and NTCP and identify the inhibitors/substrates of NTCP. In the present study, a LLC-PK1 cell model stably expressing human NTCP was established, which was simple and suitable for high throughput screening, and utilized to screen and verify the potential inhibitors of NTCP from 102 herbal medicinal ingredients. The results showed that ginkgolic acid (GA) (13 : 0), GA (15 : 1), GA (17 : 1), erythrosine B, silibinin, and emodin have inhibitory effects on NTCP uptake of TCNa in a concentration-dependent manner. Among them, GA (13 : 0) and GA (15 : 1) exhibited the stronger inhibitory effects, with IC 50 values being less than 8.3 and 13.5 μmol·L −1 , respectively, than the classical inhibitor, cyclosporin A (CsA) (IC 50 = 20.33 μmol·L −1 ). Further research demonstrated that GA (13 : 0), GA (15 : 1), GA (17 : 1), silibinin, and emodin were not substrates of NTCP. These findings might contribute to a better understanding of the disposition of the herbal ingredients in vivo , especially in biliary excretion.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Qingying Zhu,Haimin Shen,Zhujin Yang,Hongbing Ji
Nine β-cyclodextrin derivatives containing an amino group were synthesized via nucleophilic substitution from mono(6- O - p -tolylsulfonyl)-β-cyclodextrin and used in asymmetric biomimetic Michael addition reactions in water at room temperature. The mechanism responsible for the moderate activity and enantioselectivity of the β-cyclodextrin derivatives was explored using nuclear magnetic resonance spectroscopy, namely 2D 1 H rotating-frame overhauser effect spectroscopy (ROESY), ultraviolet absorption spectroscopy, and quantum chemical calculations, which provide a useful technique for investigating the formation of inclusion complexes. The effects of the pH of the reaction medium, the β-cyclodextrin derivative dosage, the structure of the modifying amino group, and various substrates on the yield and enantioselectivity were investigated. The results indicated that these factors had an important effect on the enantiomeric excess (ee) in the reaction system. Experiments using a competitor for inclusion complex formation showed that a hydrophobic cavity is necessary for enantioselective Michael addition. A comparison of the reactions using 4-nitro-β-nitrostyrene and 2-nitro-β-nitrostyrene showed that steric hindrance improved the enantioselectivity. This was verified by the optimized geometries obtained from quantum chemical calculations. An ee of 71% was obtained in the asymmetric Michael addition of cyclohexanone and 2-nitro-β-nitrostyrene, using ( S )-2-aminomethylpyrrolidine-modified β-CD as the catalyst, in an aqueous buffer solution, i.e., CH 3 COONa-HCl (pH 7.5).
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Yilong Wang,Yun Zhang,Aijun Sun,Yunfeng Hu
A novel marine microbial esterase PHE14 was cloned from the genome of Pseudomonas oryzihabitans HUP022 isolated from the deep sea of the western Pacific Ocean. Esterase PHE14 exhibited very good tolerance to most organic solvents, surfactants and metal ions tested, thus making it a good esterase candidate for organic synthesis that requires an organic solvent, surfactants or metal ions. Esterase PHE14 was utilized as a biocatalyst in the asymmetric synthesis of D-methyl lactate by enzymatic kinetic resolution. D-methyl lactate is a key chiral chemical. Contrary to some previous reports, the addition of an organic solvent and surfactants in the enzymatic reaction did not have a beneficial effect on the kinetic resolution catalyzed by esterase PHE14. Our study is the first report on the preparation of the enantiomerically enriched product D-methyl lactate by enzymatic kinetic resolution. The desired enantiomerically enriched product D-methyl lactate was obtained with a high enantiomeric excess of 99% and yield of 88.7% after process optimization. The deep sea microbial esterase PHE14 is a green biocatalyst with very good potential in asymmetric synthesis in industry and can replace the traditional organic synthesis that causes pollution to the environment.
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2016
·
IF 2.628
Haijun Chen,Chao Liu,Min Wang,Chaofeng Zhang,Gao Li,Feng Wang
Well-defined gold nanoclusters with average size less than 2 nm have emerged as a new and novel catalyst. The gold nanocluster loaded on the oxide surface usually aggregates to larger particles at high temperature (> 300 °C), which is caused by the removal of the surface ligands. We herein present a novel method to prepare Au 25 cluster catalyst (∼1.3 nm) with high thermal stability (up to 400 °C). Au 25 @SiO 2 is synthesized via a co-hydrolyzing reaction of Au 25 [SC 3 H 6 Si(OCH 3 ) 3 ] 18 and tetraethyl orthosilicate, and then it is treated at different temperature (e.g., 200, 300, 400 °C) in air to remove the organic ligands. Au 25 @SiO 2 is well characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and diffuse reflectance UV-vis spectroscopy. Further, the Au 25 @SiO 2 catalysts are investigated in the hydrogenation of p -nitrophenol into p -aminophenol.
✓ 已验证
产品关联
DOI
高影响因子
NEW CARBON MATERIALS
·
2017
·
IF 1.02
Chun-yan Chen,Xiao-ya Guo,Guang-qiang Lu,Christian Marcus Pedersen,Yan Qiao,Xiang-lin Hou,Ying-xiong Wang
Graphene oxide (GO) was used as an efficient and recyclable catalyst for the synthesis of N-substituted pyrrole using a Paal–Knorr condensation reaction between 2,5-hexanedione and aniline. The effects of reaction time, reaction temperature, solvent, catalyst loading and molar ratio of aniline to 2,5-hexanedione on the yield of 2,5-dimethyl-N-phenyl pyrrole were investigated. In situ NMR was used to follow the Paal–Knorr reaction at the molecular level. Results revealed that the oxygen-containing groups of GO, such as sulfonic acid and carboxyl groups, played a key role in this catalytic reaction. Polar protic solvents were favorable for the reaction. The catalytic activity increased with temperature without any side reaction. The GO could be easily recovered and showed remarkable reusability and excellent catalytic performance allowing it to be reused 5 times.
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2017
·
IF 2.813
Cong Zhao,Shengxin Chen,Ruirui Zhang,Zihang Li,Ruixia Liu,Baozeng Ren,Suojiang Zhang
A series of acetate ionic liquids were synthesized using a typical two-step method. The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions. The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions, obtained using ultraviolet-visible spectroscopy, and the relationship between their catalytic activities and basicities was established. The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH. This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used. A possible electrophilic-nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time-of-flight mass spectrometry . In addition, the effects of significant reaction parameters such as concentration of catalyst, molar ratio of alcohol to propylene oxide, reaction temperature, and steric hindrance of the alcohol were investigated in detail.
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）