RSC Advances
·
2015
·Vol. 5
·期 74
·60596-60607
·
IF 3.84
Lulu Pan,Jianfeng Ban,Shaorong Lu,Guoxin Chen,Jin Yang,Qiyun Luo,Linyan Wu,Jinhong Yu
Perylene tetracarboxylic anhydride (PTCDA) was reacted with 6-aminocaproic acid to form the corresponding perylene bisimide (PBI). PBI was used as the foundation for oligomerisation of glycidol in a ring-opening reaction of glycidol leading to a hyper branched, water-soluble glycidol derivative of perylene (PBI-HPG). PBI-HPG was bound to the reduced graphene oxide via π–π stacking resulting in a compound termed PBI-HPG/RGO. The structure and morphology of PBI-HPG/RGO were investigated by infrared spectroscopy (FT-IR), wide angle X-ray diffractometry (WAXD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). PBI-HPG/RGO was blended at different loadings in order to improve the thermal and mechanical properties of epoxy composites. The maximum Tg of the epoxy composites was about 20 °C and the decomposition temperature (Td) was 26 °C higher than that of neat epoxy. The incorporation of PBI-HPG/RGO yields a material with an impact strength of 39.6 kJ m−2 and a tensile strength at 0.7 wt%. It increased by 50.8% and 62.3%, respectively, compared to the neat epoxy.
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E-POLYMERS
·
2014
·Vol. 15
·期 1
·39-44
·
IF 0.33
Danjie Li,Xianbo Shen,Liang Chen,Huanchang Jiang,Jianli Wang
Covalently immobilizing the active sites or ligands on a polymer surface is an efficient strategy to achieve a full use of expensive organic parts. In this work, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was anchored onto polystyrene beads through an ether bond or an ionic liquid bridge. We quantitatively compared their thermal stabilities at nitrogen atmosphere and their chemical stabilities in a biphasic oxidation surrounding. It was found that the ionic liquid-bridged TEMPO exhibited an additional advantage of stability and could be reused for 30 consecutive recycles with a conversion ratio above 90% without any significant loss under the condition of the Montanari oxidation system (NaClO/NaBr, CH 2 Cl 2 /water), and the overall reaction time exceeded 2700 min.
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ChemCatChem
·
2014
·Vol. 7
·期 3
·441-449
·
IF 5.044
Hui Wan,Chong Chen,Zuowang Wu,Yigen Que,Yu Feng,Wei Wang,Lei Wang,Guofeng Guan,Xiaoqin Liu
Graphical Be more active: A new strategy is proposed to construct the ionic liquid, polyoxometalate (POM), and metal–organic framework (MOF) composite. POM bridges the gap between the ionic liquid and the carrier (MOF); thus, the heteropolyanion-based ionic liquid can be encapsulated within the cages of MIL-100 (MIL=Materials of Institut Lavoisier) through anion exchange. The POM–ionic-liquid-functionalized MOF demonstrates high catalytic activity for the esterification of oleic acid with ethanol and is stable in the liquid-phase reaction, with no obvious leaching of the active component. A new strategy was proposed to construct the ionic liquid, polyoxometalate (POM), and metal–organic framework (MOF) composite. The POM-based MOF was synthesized by using the direct hydrothermal method. The sulfonic acid group-functionalized ionic liquid was used for further modification of the hybrid material to realize the encapsulation of the heteropolyanion-based ionic liquid within the cages of the MOF. The catalysts were characterized by using XRD, N 2 adsorption–desorption, FTIR, SEM, TEM, elemental analysis, and TGA. The results indicated that the heteropolyanion-based ionic liquid had been successfully encapsulated within the cages and the structure of MIL-100 (MIL=Materials of Institut Lavoisier) remained intact. The POM–ionic-liquid-functionalized MOF, with high content of the active component, had both Lewis and Brønsted acid sites, which led to high catalytic activity for the esterification of oleic acid with ethanol. The esterification reaction conditions were optimized by using response surface methodology (RSM), and the corresponding conversion of oleic acid reached 94.6 %. The catalyst could be easily recovered and reused six times without significant loss of activity.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2017
·
IF 1.174
Xingxing Wang,Peng Zhang,Penglei Cui,Weiguo Cheng,Suojiang Zhang
A large number of surplus glycerol from the biodiesel production can be used as renewable feedstock to produce glycerol carbonate. In this paper, a series of guanidine-based ionic liquids were synthesized to catalyze the transesterification of glycerol and dimethyl carbonate. The tunable basicity and the anion–cation cooperative effect were responsible for the obtained results. The [TMG][TFE] showed the best activity (turnover frequency (TOF) of 1754.0 h − 1 , glycerol (GL) conversion of 91.8%, glycerol carbonate (GC) selectivity of 95.5%) at 80 °C with 0.1 mol% catalyst for 30 min. The reaction mechanism of the transesterification was also proposed.
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ANALYTICA CHIMICA ACTA
·
2016
·
IF 4.712
Na Xu,Hong-Wei Li,Yuqing Wu
A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra , X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths , and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body.
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PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 43
·37110-37117
·
IF 3.289
Mingjuan Han,Zheng Gu,Chong Chen,Zuowang Wu,Yigen Que,Qiang Wang,Hui Wan,Guofeng Guan
A new, simple and effective strategy to confine dicationic acid ionic liquids (DAILs, 1,4-bis[3-(propyl-3-sulfonate) imidazolium] butane hydrogen sulfate) in the cages of MIL-100(Fe) frameworks was constructed. The target catalyst, defined as MIL-100(Fe)@DAILs, was characterized by XRD, FTIR, SEM, TEM, EA, TGA and N2 adsorption–desorption. Meanwhile, the catalytic activity of the MIL-100(Fe)@DAILs catalyst was evaluated by the esterification reaction with oleic acid and methanol. The results indicated that the DAILs had been effectively encapsulated within the cages of the MIL-100(Fe) frameworks. Moreover, the influence of reaction time, reaction temperature, molar ratio of methanol to oleic acid and catalyst dosage on the conversion of oleic acid was studied by univariate analysis. The conversion of oleic acid decreased from 93.5% to 86.0% when the catalyst was reused five times, which indicated that the target catalyst possessed higher catalytic activity and superior catalytic activity. Finally, an esterification mechanism catalyzed by this novel catalyst was illustrated.
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ANALYTICAL CHEMISTRY
·
2017
·
IF 6.32
Huan Zeng,Chu-Bo Qi,Ting Liu,Hua-Ming Xiao,Qing-Yun Cheng,Han-Peng Jiang,Bi-Feng Yuan,Yu-Qi Feng
5-Methylcytosine (5-mC) is an important epigenetic mark that plays critical roles in a variety of cellular processes. To properly exert physiological functions, the distribution of 5-mC needs to be tightly controlled in both DNA and RNA. In addition to methyltransferase-mediated DNA and RNA methylation, premethylated nucleotides can be potentially incorporated into DNA and RNA during replication and transcription. To exclude the premodified nucleotides into DNA and RNA, endogenous 5-methyl-2′-deoxycytidine monophosphate (5-Me-dCMP) generated from nucleic acids metabolism can be enzymatically deaminated to thymidine monophosphate (TMP). Therefore, previous studies failed to detect 5-Me-dCMP or 5-methylcytidine monophosphate (5-Me-CMP) in cells. In the current study, we established a method by chemical labeling coupled with liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS/MS) for sensitive and simultaneous determination of 10 nucleotides, including 5-Me-dCMP and 5-Me-CMP. As N,N-dimethyl-p-phenylenediamine (DMPA) was utilized for labeling, the detection sensitivities of nucleotides increased by 88–372-fold due to the introduction of a tertiary amino group and a hydrophobic moiety from DMPA. Using this method, we found that endogenous 5-Me-dCMP and 5-Me-CMP widely existed in cultured human cells, human tissues, and human urinary samples. The presence of endogenous 5-Me-dCMP and 5-Me-CMP indicates that deaminases may not fully deaminate these methylated nucleotides. Consequently, the remaining premethylated nucleosides could be converted to nucleoside triphosphates as building blocks for DNA and RNA synthesis. Furthermore, we found that the contents of 5-Me-dCMP and 5-Me-CMP exhibited significant decreases in renal carcinoma tissues and urine samples of lymphoma patients compared to their controls, probably due to more reutilization of methylated nucleotides in DNA and RNA synthesis. This study is, to the best of our knowledge, the first report for detecting endogenous 5-Me-dCMP and 5-Me-CMP in mammals. The detectable endogenous methylated nucleotides indicate the potential deleterious effects of premodified nucleotides on aberrant gene regulation in cancers.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Xia Chen,Wangyang Lu,Tiefeng Xu,Nan Li,Zhexin Zhu,Gangqiang Wang,Wenxing Chen
As highly active species, in theory, hydroxyl radicals ( OH) can move freely and destroy almost all organic compounds, including catalysts with a conjugate structure. Therefore, a system that can generate oxidative species with a high activity, but where the active species is anchored to avoid autooxidation, is urgently required. In this work, we fabricated a novel visible-light-assisted advanced oxidation process based on high-valent iron species (Fe(IV) O) over graphitic carbon nitride (g-C 3 N 4 ) that was coordinated to iron hexadecachlorophthalocyanine (FePcCl 16 ) through imidazole ligands (IMD). Under visible-light excitation, the phthalocyanine ring of the g-C 3 N 4 -IMD-FePcCl 16 /hydrogen peroxide (H 2 O 2 ) can be motivated to an excited state FePcCl 16 ∗ , in which active H 2 O 2 and the generation of anchored Fe(IV) O species are used for the degradation of carbamazepine (CBZ). Because the molecular movement of transient Fe(IV) O species is restricted, the possibility of oxidative collision is minimized, which provides good stability. An analysis of the electron paramagnetic resonance, gas chromatography/mass spectrometry, photoluminescence spectra, periodic on/off photocurrent density response and the photo-assisted catalytic active experiments, indicates that the rapid generation of Fe(IV) O species occurs as the catalyst contacts the H 2 O 2 , which inhibits the conduction-band electrons of the g-C 3 N 4 from reacting with H 2 O 2 and generating OH. This study provides insight into the construction of suitable structures that will enhance visible-light-assisted catalytic oxidation activity and allow for the fabrication of an anchored highly active species.
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REACTIVE & FUNCTIONAL POLYMERS
·
2016
·
IF 2.725
Na Tian,Xufeng Ni,Zhiquan Shen
Imidazolium-functionalized hyperbranched polymeric ionic liquids (HPILs) are synthesized by one-step reaction between tri-imidazolium-based ester (A 3 monomer) and dihaloalkane (B 2 monomer), which can act as efficient stabilizers in the preparation of silver nanoparticles . The particle size and solubility of nanoparticles mainly depend on the chemical structure of stabilizer, molecular weights of HPILs, and concentration of reagent. The obtained HPIL-encapsulated Ag nanoparticles were characterized by ultraviolet–visible (UV–Vis) absorption and transmission electron microscopy , showing a uniform size distribution and appreciable stability in water for a longer period.
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JOURNAL OF CHEMICAL THERMODYNAMICS
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2016
·
IF 2.196
Fangfang Ye,Jiahong Zhu,Keke Yu,Ruyu Zhu,Yingjie Xu,Jiayi Chen,Lingxiao Chen
In this work, densities and viscosities of aqueous solution of 1,1,3,3-tetramethylguanidine imidazolide ([TMG]IM) ionic liquid were measured at temperatures from T = (293.15 to 313.15) K. Volumetric properties including excess molar volumes V E , apparent molar volumes, partial molar volumes, and excess partial molar volumes were calculated from the experimental density. Viscosity deviations Δ η , Gibbs energy and excess Gibbs energy of activation for viscous flow were deduced from the viscosity. Moreover, electrical conductivities κ and refractive indices of binary mixtures of [TMG]IM with water and alcohols were determined at 298.15 K. The results show that V E values of {[TMG]IM (1) + water (2)} mixture are negative over the whole composition range, while Δ η and refractive index deviations Δ n D values exhibit positive deviations, indicating that the hydrogen bonding interaction between [TMG]IM and water is dominant. The absolute values of V E and Δ η of the mixture decrease with the increasing temperature. The V E , Δ η , and Δ n D can be fitted by the Redlich–Kister equation with satisfactory results. The concentration-dependent κ of the studied systems are fitted to Casteel–Amis equation, showing that the κ values of {[TMG]IM (1) + water (2)} mixture are much higher than those of {[TMG]IM (1) + ethanol (2)} mixture.
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JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES
·
2016
·
IF 2.687
Xiao-Mei He,Bi-Feng Yuan,Yu-Qi Feng
Immobilized metal affinity chromatography (IMAC) technique is frequently used in the purification of histidine-tagged (His-tagged) recombinant proteins. In this study, nickel(II)-immobilized carboxyl cotton chelator (CCC-Ni 2+ ) fibers was synthesized by a simple method based on the coordination effect between Ni 2+ and carboxyl group. The nickel content of the CCC-Ni 2+ fibers was determined to be 5 times larger than that of Ni 2+ -immobilized sulfhydryl cotton fiber (SCF-Ni 2+ ) fibers developed in our previous work. The prepared CCC-Ni 2+ fibers were then applied for the selective and rapid separation of His-tagged protein from escherichia coli ( E. coli ) cell lysates on the basis of the high affinity of Ni 2+ to 6 × His with a lab-in-syringe format. Benefiting from the good biological compatibility and high nickel content, the results showed that CCC-Ni 2+ fibers were able to selectively capture His-tagged proteins from complex E. coli cell lysates and exhibited a relatively large adsorption capacity toward His-tagged protein. The recoveries of His-tagged GFP in E. coli cell lysates were in the range of 89.8%-106.7% with the relative standard deviations (RSDs) less than 9.4% (intra-day) and 10.3% (inter-day). Taken together, this efficient approach for the purification of recombinant proteins extends the application of CCC-based fibrous materials in biological analysis.
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高影响因子
REACTIVE & FUNCTIONAL POLYMERS
·
2016
·
IF 2.725
Liang Chen,Jun Tang,Qi Zhang,Jianli Wang
In this study, we report the development of a novel recyclable polymer-supported interfacial catalyst for Montanari oxidation . The catalyst was prepared by immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on poly(ether sulfone) (PES) bridged by imidazole groups and characterized by 1 H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, elemental analysis , contact angle measurement, and transmission electron microscopy (TEM). This well-designed polymer was self-assembled into nanoaggregates in CH 2 Cl 2 . It was then used as Pickering emulsifier in Montanari oxidation system (NaClO/NaBr/immobilized TEMPO) for selective oxidation of different alcohols, which exhibited higher activity due to the enhanced mass transfer through microreactor mechanism. Moreover, this polymeric interfacial catalyst was pH-sensitive and could be easily recycled by adding small amount of acid, and subsequent cycles of alcohol oxidation showed no loss on either conversion or selectivity. This study represents an innovative approach for developing polymeric interfacial catalyst.
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