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2015 Volume 26 Issue 11
2015, 26(11): 1331-1335
doi: 10.1016/j.cclet.2015.08.010
Abstract:
Echinoside A is a triterpene saponin isolated from the sea cucumber Actinopyga echinites (JAEGER), which displays potent antitumor activities in vitro and in vivo. Here, we report the synthesis of the ABC-fused ring skeleton of the aglycon of Echinoside A, with the enantiomerically pure (+)-Wieland-Miescher ketone being used as starting material and a Robinson annulation as the key reaction.
Echinoside A is a triterpene saponin isolated from the sea cucumber Actinopyga echinites (JAEGER), which displays potent antitumor activities in vitro and in vivo. Here, we report the synthesis of the ABC-fused ring skeleton of the aglycon of Echinoside A, with the enantiomerically pure (+)-Wieland-Miescher ketone being used as starting material and a Robinson annulation as the key reaction.
2015, 26(11): 1336-1340
doi: 10.1016/j.cclet.2015.08.009
Abstract:
Amild and efficient iridium-catalyzed ortho-C-H amidation with sulfonyl azides by weakly coordinating carboxylic acid was demonstrated, which provided a novel approach to anthranilic acid derivatives.
Amild and efficient iridium-catalyzed ortho-C-H amidation with sulfonyl azides by weakly coordinating carboxylic acid was demonstrated, which provided a novel approach to anthranilic acid derivatives.
2015, 26(11): 1341-1344
doi: 10.1016/j.cclet.2015.07.004
Abstract:
First total synthesis of norleucosceptroids F and G has been achieved through key steps of Michael-Aldol cascade, oxa-Michael cyclization-dehydration-deprotection cascade and cross metathesis (CM), this work developed a general and concise method to the synthesis of leucosceptroid and norleucosceptroid.
First total synthesis of norleucosceptroids F and G has been achieved through key steps of Michael-Aldol cascade, oxa-Michael cyclization-dehydration-deprotection cascade and cross metathesis (CM), this work developed a general and concise method to the synthesis of leucosceptroid and norleucosceptroid.
2015, 26(11): 1345-1350
doi: 10.1016/j.cclet.2015.06.019
Abstract:
Ultrafine Ru nanoparticles are successfully deposited on MCM-41 by using a simple liquid impregnationreduction method, and further investigated for catalytic hydrolysis of ammonia borane and methylamine borane. Among all the catalysts tested, 1.12 wt% Ru/MCM-41 exhibits the highest catalytic activity, with turnover frequency value of 288 min-1.
Ultrafine Ru nanoparticles are successfully deposited on MCM-41 by using a simple liquid impregnationreduction method, and further investigated for catalytic hydrolysis of ammonia borane and methylamine borane. Among all the catalysts tested, 1.12 wt% Ru/MCM-41 exhibits the highest catalytic activity, with turnover frequency value of 288 min-1.
2015, 26(11): 1351-1354
doi: 10.1016/j.cclet.2015.06.018
Abstract:
Polypropylene/poly(butyl acrylate) alloy is produced by water-solid phase suspension grafting polymerization with a submicrometer microdomain where graft polymerization occurs within micropores of polypropylene particles prepared by reactor granule technology (RGT). The results show that the grafting percentage (GP) of butyl acrylate (BA) increases with the increase of the monomer concentration,which could reach 32.6% while the grafting efficiency (GE) is up to 98%. The addition of the crosslinking agent, triethylene glycol diacrylate (TEGDA), could improve GP up to 36.3%. Transmission electron microscopic (TEM) micrographs demonstrate that PBA microdomains distributed in PP matrix increase in size less than 500 nm. Moreover, TEM images show that the grafting phase exhibits a singlephase behavior with the addition of TEGDA, which implies that the ratio of graft copolymer increased.
Polypropylene/poly(butyl acrylate) alloy is produced by water-solid phase suspension grafting polymerization with a submicrometer microdomain where graft polymerization occurs within micropores of polypropylene particles prepared by reactor granule technology (RGT). The results show that the grafting percentage (GP) of butyl acrylate (BA) increases with the increase of the monomer concentration,which could reach 32.6% while the grafting efficiency (GE) is up to 98%. The addition of the crosslinking agent, triethylene glycol diacrylate (TEGDA), could improve GP up to 36.3%. Transmission electron microscopic (TEM) micrographs demonstrate that PBA microdomains distributed in PP matrix increase in size less than 500 nm. Moreover, TEM images show that the grafting phase exhibits a singlephase behavior with the addition of TEGDA, which implies that the ratio of graft copolymer increased.
2015, 26(11): 1355-1358
doi: 10.1016/j.cclet.2015.07.026
Abstract:
The Y(OTf)3-catalyzed aerobic oxidative cyclization reaction for the selective synthesis of dihydroquinazolinones and quinazolinones has been developed. This method provides a practical, effective and green synthetic approach to dihydroquinazolinones and quinazolinones which both are important units in many biologically active compounds.
The Y(OTf)3-catalyzed aerobic oxidative cyclization reaction for the selective synthesis of dihydroquinazolinones and quinazolinones has been developed. This method provides a practical, effective and green synthetic approach to dihydroquinazolinones and quinazolinones which both are important units in many biologically active compounds.
2015, 26(11): 1359-1363
doi: 10.1016/j.cclet.2015.06.008
Abstract:
The effect of potassium (K) promoter on the catalytic performance of activated carbon (AC) supported Wacker-type catalysts (PdCl2-CuCl2/AC) for the synthesis of dimethyl carbonate (DMC) from CO and methyl nitrite (MN) was investigated by means of N2 adsorption, H2-temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the space time yield of DMC on Wacker-type catalysts with different K promoters ranked in the following order: KCl > KOH > CH3COOK > K2CO3. Especially, the addition of KCl significantly improved the catalytic activities of PdCl2-CuCl2/AC catalyst for DMC synthesis from CO and MN. N2 adsorption data indicated that the addition of K promoters did not change the textural properties of Wacker-type catalysts greatly. H2-TPR and XPS results demonstrated that the existence of KCl promoted the reducibility of Cu2+ species and increased the proportion of Cu2+ species on catalyst surface, which is favorable for oxidizing Pd0 to active Pd2+. Further, the addition of KCl benefited the reactivity of PdCl2- CuCl2/AC catalyst for DMC synthesis from CO and MN.
The effect of potassium (K) promoter on the catalytic performance of activated carbon (AC) supported Wacker-type catalysts (PdCl2-CuCl2/AC) for the synthesis of dimethyl carbonate (DMC) from CO and methyl nitrite (MN) was investigated by means of N2 adsorption, H2-temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the space time yield of DMC on Wacker-type catalysts with different K promoters ranked in the following order: KCl > KOH > CH3COOK > K2CO3. Especially, the addition of KCl significantly improved the catalytic activities of PdCl2-CuCl2/AC catalyst for DMC synthesis from CO and MN. N2 adsorption data indicated that the addition of K promoters did not change the textural properties of Wacker-type catalysts greatly. H2-TPR and XPS results demonstrated that the existence of KCl promoted the reducibility of Cu2+ species and increased the proportion of Cu2+ species on catalyst surface, which is favorable for oxidizing Pd0 to active Pd2+. Further, the addition of KCl benefited the reactivity of PdCl2- CuCl2/AC catalyst for DMC synthesis from CO and MN.
2015, 26(11): 1364-1366
doi: 10.1016/j.cclet.2015.07.013
Abstract:
A novel poly(styrene-co-acrylonitrile)-graft-polyethylene glycol (SAN-g-PEG) copolymer was synthesized as new solid-solid phase change materials (SSPCMs) by grafting PEG to the main chain of poly(styrene-co-acrylonitrile). The chemical structure of the SAN-g-PEG was confirmed by the Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy techniques. The thermal energy storage properties and the storage durability of the SAN-g-PEG were investigated by differential scanning calorimetry (DSC). The SAN-g-PEG was endowed with the solid- solid phase transition temperatures within the range of 23-36 ℃ and the latent heat enthalpy ranged from 66.8 kJ/kg to 68.3 kJ/kg. Thermal cycling tests revealed that the SAN-g-PEG kept great heat storage durability after 1000 thermal cycles. The thermal stabilitywas evaluated by a thermal gravity analysis (TGA), and the initial decomposition temperature (Td) of SAN-g-PEG is 350 ℃, which proves that the SAN-g-PEG possessed good thermal stability.
A novel poly(styrene-co-acrylonitrile)-graft-polyethylene glycol (SAN-g-PEG) copolymer was synthesized as new solid-solid phase change materials (SSPCMs) by grafting PEG to the main chain of poly(styrene-co-acrylonitrile). The chemical structure of the SAN-g-PEG was confirmed by the Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy techniques. The thermal energy storage properties and the storage durability of the SAN-g-PEG were investigated by differential scanning calorimetry (DSC). The SAN-g-PEG was endowed with the solid- solid phase transition temperatures within the range of 23-36 ℃ and the latent heat enthalpy ranged from 66.8 kJ/kg to 68.3 kJ/kg. Thermal cycling tests revealed that the SAN-g-PEG kept great heat storage durability after 1000 thermal cycles. The thermal stabilitywas evaluated by a thermal gravity analysis (TGA), and the initial decomposition temperature (Td) of SAN-g-PEG is 350 ℃, which proves that the SAN-g-PEG possessed good thermal stability.
2015, 26(11): 1367-1370
doi: 10.1016/j.cclet.2015.06.003
Abstract:
MnO2 was doped into a conducting copolymer, poly(aniline-co-o-aminophenol) (PANOA), via a one-step process during the chemical oxidative polymerization. The doping of MnO2 could enhance the electrochemical activity and reversibility of the copolymer. When used as the electrode materials of a supercapacitor, the capacitive behaviors of the as-prepared PANOA-MnO2 were superior to those of pure PANOA, especially at high potential scan rate and high charge-discharge current density. The MnO2 doped copolymer also had an excellent cyclic performance.
MnO2 was doped into a conducting copolymer, poly(aniline-co-o-aminophenol) (PANOA), via a one-step process during the chemical oxidative polymerization. The doping of MnO2 could enhance the electrochemical activity and reversibility of the copolymer. When used as the electrode materials of a supercapacitor, the capacitive behaviors of the as-prepared PANOA-MnO2 were superior to those of pure PANOA, especially at high potential scan rate and high charge-discharge current density. The MnO2 doped copolymer also had an excellent cyclic performance.
2015, 26(11): 1371-1375
doi: 10.1016/j.cclet.2015.08.004
Abstract:
A method of hydrophilic interaction liquid chromatography with indirect ultraviolet detection was developed to determine three pyrrolidinium ionic liquid cations, i.e. N-methyl-N-ethyl pyrrolidinium cation ([MEPy]+), N-methyl-N-propyl pyrrolidinium cation ([MPPy]+) and N-methyl-N-butyl pyrrolidinium cation ([MBPy]+). Chromatographic separation was achieved on a hydrophilic column using imidazolium ionic liquids and organic solvents as the mobile phase. The effects of the background ultraviolet absorption reagents, the imidazolium ionic liquids, detection wavelength, organic solvents, column temperature and the pH value of the mobile phase on the separation and determination of pyrrolidinium cations were investigated and the retention behaviors in hydrophilic interaction chromatography were discussed. The optimized chromatographic conditions were selected. Under the optimal conditions, the detection limits (S/N = 3) for [MEPy]+, [MPPy]+ and [MBPy]+ were 0.59, 0.53 and 0.46 mg/L, respectively. The method has been successfully applied to the determination of the three ionic liquids synthesized in our chemistry laboratory. This research results may improve the analytical method of ionic liquid cations.
A method of hydrophilic interaction liquid chromatography with indirect ultraviolet detection was developed to determine three pyrrolidinium ionic liquid cations, i.e. N-methyl-N-ethyl pyrrolidinium cation ([MEPy]+), N-methyl-N-propyl pyrrolidinium cation ([MPPy]+) and N-methyl-N-butyl pyrrolidinium cation ([MBPy]+). Chromatographic separation was achieved on a hydrophilic column using imidazolium ionic liquids and organic solvents as the mobile phase. The effects of the background ultraviolet absorption reagents, the imidazolium ionic liquids, detection wavelength, organic solvents, column temperature and the pH value of the mobile phase on the separation and determination of pyrrolidinium cations were investigated and the retention behaviors in hydrophilic interaction chromatography were discussed. The optimized chromatographic conditions were selected. Under the optimal conditions, the detection limits (S/N = 3) for [MEPy]+, [MPPy]+ and [MBPy]+ were 0.59, 0.53 and 0.46 mg/L, respectively. The method has been successfully applied to the determination of the three ionic liquids synthesized in our chemistry laboratory. This research results may improve the analytical method of ionic liquid cations.
2015, 26(11): 1376-1380
doi: 10.1016/j.cclet.2015.08.001
Abstract:
A catalytic synthesis of N-benzothiazol-2-yl-amides from 1-acyl-3-(phenyl)thioureas was achieved in the presence of a palladium catalyst through the C(sp2)-H functionalization/C-S bond formation. This synthetic methodology can produce various N-benzothiazol-2-yl-amides in high yields with good functional group tolerance.
A catalytic synthesis of N-benzothiazol-2-yl-amides from 1-acyl-3-(phenyl)thioureas was achieved in the presence of a palladium catalyst through the C(sp2)-H functionalization/C-S bond formation. This synthetic methodology can produce various N-benzothiazol-2-yl-amides in high yields with good functional group tolerance.
2015, 26(11): 1381-1384
doi: 10.1016/j.cclet.2015.07.007
Abstract:
A convenient and efficient approach for difluoroalkyl-containing γ-butyrolactones via the radical addition reaction of iododifluoromethyl ketones with 4-pentenoic acids initiated by AIBN in CH3CN at 60 ℃ was reported. Various difluoroalkyl-containing δ-valerolactones were also synthesized under this reaction conditions.
A convenient and efficient approach for difluoroalkyl-containing γ-butyrolactones via the radical addition reaction of iododifluoromethyl ketones with 4-pentenoic acids initiated by AIBN in CH3CN at 60 ℃ was reported. Various difluoroalkyl-containing δ-valerolactones were also synthesized under this reaction conditions.
2015, 26(11): 1385-1388
doi: 10.1016/j.cclet.2015.07.010
Abstract:
A highly efficient and environmentally benign protocol for the synthesis of 2-amino-5,7-dimethoxy-4- aryl/alkyl-4H-chromene-3-carbonitrile derivatives by one-pot three-component coupling reacting of aromatic aldehydes, malononitrile and 3,5-dimethoxy phenol under reflux condition has been developed in aqueous EtOH media using Na2O-Al2O3-P2O5 glass-ceramic system.
A highly efficient and environmentally benign protocol for the synthesis of 2-amino-5,7-dimethoxy-4- aryl/alkyl-4H-chromene-3-carbonitrile derivatives by one-pot three-component coupling reacting of aromatic aldehydes, malononitrile and 3,5-dimethoxy phenol under reflux condition has been developed in aqueous EtOH media using Na2O-Al2O3-P2O5 glass-ceramic system.
2015, 26(11): 1389-1392
doi: 10.1016/j.cclet.2015.06.005
Abstract:
Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of e-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N',N''-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactammagnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity (1.51), decreasedmelting temperature (218 ℃) and lower crystallinity (24.2%). The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.
Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of e-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N',N''-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactammagnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity (1.51), decreasedmelting temperature (218 ℃) and lower crystallinity (24.2%). The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.
2015, 26(11): 1393-1396
doi: 10.1016/j.cclet.2015.07.006
Abstract:
A novel synthetic approach to (±)-Z-recifeiolide 6, a 12-membered-ring lactone which can be selectively isomerized into (E)-recifeiolide, a natural antibiotic product isolated from fungus (Cephalosporium recifei) is reported. The synthesis is accomplished in five steps starting from readily available cyclooctanone and acetaldehyde based on the Lewis acid-catalyzed TMS-directed oxy-2-oxonia-Cope rearrangement. The work represents a novel strategy to assemble related macrolides.
A novel synthetic approach to (±)-Z-recifeiolide 6, a 12-membered-ring lactone which can be selectively isomerized into (E)-recifeiolide, a natural antibiotic product isolated from fungus (Cephalosporium recifei) is reported. The synthesis is accomplished in five steps starting from readily available cyclooctanone and acetaldehyde based on the Lewis acid-catalyzed TMS-directed oxy-2-oxonia-Cope rearrangement. The work represents a novel strategy to assemble related macrolides.
2015, 26(11): 1397-1399
doi: 10.1016/j.cclet.2015.07.009
Abstract:
A cost-effective, highly useful and eco-friendly procedure for the one-pot synthesis of highly substituted pyrazole derivatives has been developed via the reaction of various aldehydes, malononitrile and phenylhydrazine or 4-phenylthiosemicarbazide in PEG-400 and water at room temperature under ultrasound irradiation. Utilization of green solvents without a catalyst makes this methodology very interesting from economic and environmental perspectives. This method provides several advantages such as operational simplicity, use of accessible and economical starting materials and reduced environmental consequences.
A cost-effective, highly useful and eco-friendly procedure for the one-pot synthesis of highly substituted pyrazole derivatives has been developed via the reaction of various aldehydes, malononitrile and phenylhydrazine or 4-phenylthiosemicarbazide in PEG-400 and water at room temperature under ultrasound irradiation. Utilization of green solvents without a catalyst makes this methodology very interesting from economic and environmental perspectives. This method provides several advantages such as operational simplicity, use of accessible and economical starting materials and reduced environmental consequences.
2015, 26(11): 1400-1402
doi: 10.1016/j.cclet.2015.07.021
Abstract:
It is well known that zinc ions play an indispensable role in the structure and function of a large number of biological process and relevant bio-macromolecules. When some cancers occurred, the relevant concentration of zinc ions considerably decreased. Since cancer cells have a completely different redox homeostasis from normal cells, in this contribution, we have explored the possibility of bio-imaging or labeling of cancer cells through the in situ biosynthesized zinc nanoclusters by cancerous cells. The results demonstrate that we can readily realize the in vivo fluorescent bio-imaging of cancer cells through the in situ biosynthesis of the biocompatible zinc nanoclusters from cancerous cells (i.e., Hela cervical carcinoma cell line and others) when target cells cultured with micromolar zinc gluconate solutions.
It is well known that zinc ions play an indispensable role in the structure and function of a large number of biological process and relevant bio-macromolecules. When some cancers occurred, the relevant concentration of zinc ions considerably decreased. Since cancer cells have a completely different redox homeostasis from normal cells, in this contribution, we have explored the possibility of bio-imaging or labeling of cancer cells through the in situ biosynthesized zinc nanoclusters by cancerous cells. The results demonstrate that we can readily realize the in vivo fluorescent bio-imaging of cancer cells through the in situ biosynthesis of the biocompatible zinc nanoclusters from cancerous cells (i.e., Hela cervical carcinoma cell line and others) when target cells cultured with micromolar zinc gluconate solutions.
2015, 26(11): 1403-1408
doi: 10.1016/j.cclet.2015.06.007
Abstract:
The nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO2 particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O2, many nano SnO2 particles were uniformly covered on the surface of LiNi1/3Co1/3Mn1/3O2 and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO2 could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade.
The nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO2 particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O2, many nano SnO2 particles were uniformly covered on the surface of LiNi1/3Co1/3Mn1/3O2 and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO2 could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade.
2015, 26(11): 1409-1414
doi: 10.1016/j.cclet.2015.06.001
Abstract:
In this paper, the precise construction on the structure of silicalite-1 microcapsules (S1) was specifically described. The interior carbon modifications and the outside mesoporous functionalizations were successfully conducted and each sample was characterized in detail. It was found that the carbon networks could be formed inside the zeolite microcapsules via the pretreatment of sugar injections. The uniformity of the distinct microcapsule could be regulated by adjusting the sugar concentrations. With the encapsulated Pt species inside the MSSs, the nano-particles could be dispersed well within the carbon network. On the other hand, during the fabrication of the mesoporous materials outside the microcapsules, the template and the acidity of the system could play an important role in determining the morphology of S1. Besides, the PDDA modification on the shell of S1 could help the combination of the meso-layer and the shell of S1 at nano-scale. The thickness of the outside mesopore could be modulated through the controlling of the silica content.
In this paper, the precise construction on the structure of silicalite-1 microcapsules (S1) was specifically described. The interior carbon modifications and the outside mesoporous functionalizations were successfully conducted and each sample was characterized in detail. It was found that the carbon networks could be formed inside the zeolite microcapsules via the pretreatment of sugar injections. The uniformity of the distinct microcapsule could be regulated by adjusting the sugar concentrations. With the encapsulated Pt species inside the MSSs, the nano-particles could be dispersed well within the carbon network. On the other hand, during the fabrication of the mesoporous materials outside the microcapsules, the template and the acidity of the system could play an important role in determining the morphology of S1. Besides, the PDDA modification on the shell of S1 could help the combination of the meso-layer and the shell of S1 at nano-scale. The thickness of the outside mesopore could be modulated through the controlling of the silica content.
2015, 26(11): 1415-1420
doi: 10.1016/j.cclet.2015.06.006
Abstract:
Silver nanoparticles were prepared in situ using sunlight and cationic surfactants. Silver nano-particles were confirmed using UV-vis spectrophotometry, transmission electron microscopy (TEM), electron diffraction, dynamic light scattering (DLS) and FTIR. Increasing the hydrophobic chain length of surfactants increase the amount of silver nano-particles formed in addition to increasing their stability. The results showed formed, uniform, well arranged hexagonal and spherical shapes. The prepared silver nanoparticles exhibit enhanced biological activity against Gram-positive, Gram-negative bacteria and sulfate reducing bacteria (SRB).
Silver nanoparticles were prepared in situ using sunlight and cationic surfactants. Silver nano-particles were confirmed using UV-vis spectrophotometry, transmission electron microscopy (TEM), electron diffraction, dynamic light scattering (DLS) and FTIR. Increasing the hydrophobic chain length of surfactants increase the amount of silver nano-particles formed in addition to increasing their stability. The results showed formed, uniform, well arranged hexagonal and spherical shapes. The prepared silver nanoparticles exhibit enhanced biological activity against Gram-positive, Gram-negative bacteria and sulfate reducing bacteria (SRB).
2015, 26(11): 1421-1425
doi: 10.1016/j.cclet.2015.07.028
Abstract:
A triethylene glycol modified glassy carbon electrode (TEG-GCE) was fabricated by a controlledpotential electrolysis procedure. The performance of the film on the modified electrode surface was investigated by cyclic voltammetry with different probes. It was firstly found that while neutral pieces could penetrate the TEG film on the GCE surface, the ionic pieces, whatever it is anion or cation, was blocked by the film. This property was successfully used for determining dopamine (DA) in the presence of ascorbic acid (AA) with differential pulse voltammetry (DPV).
A triethylene glycol modified glassy carbon electrode (TEG-GCE) was fabricated by a controlledpotential electrolysis procedure. The performance of the film on the modified electrode surface was investigated by cyclic voltammetry with different probes. It was firstly found that while neutral pieces could penetrate the TEG film on the GCE surface, the ionic pieces, whatever it is anion or cation, was blocked by the film. This property was successfully used for determining dopamine (DA) in the presence of ascorbic acid (AA) with differential pulse voltammetry (DPV).
2015, 26(11): 1426-1430
doi: 10.1016/j.cclet.2015.06.004
Abstract:
Uniform arrays of coarse and smooth gold nanoparticles with diameter about 130 nm were successfully synthesized through seed-mediated growth method, separately. Scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction (XRD) have been used to study the formation and structure of the nanocomposites. The high enhancement factor for surface-enhanced Raman scattering of coarse and smooth gold nanoparticles were estimated to be about 3.1 × 106 and 2.0 × 106, respectively. It is evident that the coarse gold nanostructures has higher influence factor than the smooth gold nanostructures. Therefore, these unique properties of the coarse Au nanoparticles appear to be very promising for applications as high-performance SERS substrates.
Uniform arrays of coarse and smooth gold nanoparticles with diameter about 130 nm were successfully synthesized through seed-mediated growth method, separately. Scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction (XRD) have been used to study the formation and structure of the nanocomposites. The high enhancement factor for surface-enhanced Raman scattering of coarse and smooth gold nanoparticles were estimated to be about 3.1 × 106 and 2.0 × 106, respectively. It is evident that the coarse gold nanostructures has higher influence factor than the smooth gold nanostructures. Therefore, these unique properties of the coarse Au nanoparticles appear to be very promising for applications as high-performance SERS substrates.
2015, 26(11): 1431-1434
doi: 10.1016/j.cclet.2015.07.005
Abstract:
An efficient biocatalytic process has been developed to obtain optically pure (1S,4R)-N-(benzylcarbamoyl)- 4-aminocyclopent-2-en-1-ol which can be used as the key intermediate of ticagrelor. In this research, several N-(benzylcarbamoyl)-4-aminocyclopent-2-en-1-ol derivatives have been investigated in which Candida antarctica lipase B (CALB) was used to catalyze the asymmetric hydrolysis reaction. As expected, some of these substrates successfully gave (1S,4R)-N-(benzylcarbamoyl)-4-aminocyclopent- 2-en-1-ol in >98% enantiomeric excess (ee) with conversion yields up to 45%.
An efficient biocatalytic process has been developed to obtain optically pure (1S,4R)-N-(benzylcarbamoyl)- 4-aminocyclopent-2-en-1-ol which can be used as the key intermediate of ticagrelor. In this research, several N-(benzylcarbamoyl)-4-aminocyclopent-2-en-1-ol derivatives have been investigated in which Candida antarctica lipase B (CALB) was used to catalyze the asymmetric hydrolysis reaction. As expected, some of these substrates successfully gave (1S,4R)-N-(benzylcarbamoyl)-4-aminocyclopent- 2-en-1-ol in >98% enantiomeric excess (ee) with conversion yields up to 45%.
