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2014 Volume 25 Issue 4
2014, 25(4): 487-490
doi: 10.1016/j.cclet.2013.12.019
Abstract:
The interfacial assembly of photo-induced dimerization of atypical anthracene-containing amphiphilic dendron and host-guest interaction with γ-cyclodextrin has been investigated. It has been proved that even without long alkyl chain the amphiphilic dendron could still form stable Langmuir monolayer at the air/water interface. Through the host-guest interaction, γ-cyclodextrin can be used to encapsulate two headgroups of amphiphilic dendron in the antiparallel direction. However, the formed host-guest complex was sensitive to the surface pressure. Slight compression of surface pressure led amphiphilic dendron to reassemble into nanofibers through the strong π-π stacking between headgroups. On the other hand, under in situ irradiation, the amphiphilic dendron was stabilized in the cavity of gcyclodextrin through headgroup dimerization and the host-guest complex further irregularly aggregated to nanoparticles. Meanwhile, γ-cyclodextrin, as a silencer, blocked the supramolecular chirality transfer. Our conclusion was demonstrated through UV/vis, FT-IR, CD spectrum and AFM images, respectively.
The interfacial assembly of photo-induced dimerization of atypical anthracene-containing amphiphilic dendron and host-guest interaction with γ-cyclodextrin has been investigated. It has been proved that even without long alkyl chain the amphiphilic dendron could still form stable Langmuir monolayer at the air/water interface. Through the host-guest interaction, γ-cyclodextrin can be used to encapsulate two headgroups of amphiphilic dendron in the antiparallel direction. However, the formed host-guest complex was sensitive to the surface pressure. Slight compression of surface pressure led amphiphilic dendron to reassemble into nanofibers through the strong π-π stacking between headgroups. On the other hand, under in situ irradiation, the amphiphilic dendron was stabilized in the cavity of gcyclodextrin through headgroup dimerization and the host-guest complex further irregularly aggregated to nanoparticles. Meanwhile, γ-cyclodextrin, as a silencer, blocked the supramolecular chirality transfer. Our conclusion was demonstrated through UV/vis, FT-IR, CD spectrum and AFM images, respectively.
2014, 25(4): 491-495
doi: 10.1016/j.cclet.2014.01.003
Abstract:
The MWCNT-TiO2 hybrid materials were prepared by a simply mixing method and used as a counter electrode (CE) for dye-sensitized solar cells. Compared with the platinum CE, MWCNT-TiO2 CE has the similar redox voltage and current response in the cyclic voltammetry. The electrochemical catalytic activity was characterized by the electrochemical impedance spectroscopy and Tafel curve, including the equivalent circuit, the exchange current density, the limiting diffusion current density, and the diffusion coefficient of triiodide/iodide redox species. The results indicate that the reduction process from triiodide to iodide is determined by the kinetic-controlled and diffusion-limited processes. The device performance is optimal based on the MWCNT-TiO2 (mass ratio of 2:1) CE, such as the open-circuit voltage of 0.72 V, the short-circuit photocurrent density of 15.71 mA/cm2, the fill factor of 0.68, and the photon-to-electron conversion efficiency of 7.69%.
The MWCNT-TiO2 hybrid materials were prepared by a simply mixing method and used as a counter electrode (CE) for dye-sensitized solar cells. Compared with the platinum CE, MWCNT-TiO2 CE has the similar redox voltage and current response in the cyclic voltammetry. The electrochemical catalytic activity was characterized by the electrochemical impedance spectroscopy and Tafel curve, including the equivalent circuit, the exchange current density, the limiting diffusion current density, and the diffusion coefficient of triiodide/iodide redox species. The results indicate that the reduction process from triiodide to iodide is determined by the kinetic-controlled and diffusion-limited processes. The device performance is optimal based on the MWCNT-TiO2 (mass ratio of 2:1) CE, such as the open-circuit voltage of 0.72 V, the short-circuit photocurrent density of 15.71 mA/cm2, the fill factor of 0.68, and the photon-to-electron conversion efficiency of 7.69%.
2014, 25(4): 496-500
doi: 10.1016/j.cclet.2014.02.001
Abstract:
Nanoporous metals (NPMs) show potential applications as enzyme-free glucose sensors. There are few reports on nanoporous Pd in this area even though their cost is much lower than other NPMs. In this work, we report the formation of Pd-based NPM with improved catalytic activity towards the oxidation of glucose. By dealloying metallic glasses, Pd-based NPMs with bi-continuous networks were obtained. All the Pd-based NPMs show high electrochemical catalytic activity towards glucose oxidation. In this study, NPM with an open, three-dimensional, ligament-channel nanoporous structure resulted by dealloying metallic Pd30Cu40Ni10P20, producing a pore size of 11 nm and a ligament size of 7 nm as the best configuration towards the direct oxidation reaction of glucose.
Nanoporous metals (NPMs) show potential applications as enzyme-free glucose sensors. There are few reports on nanoporous Pd in this area even though their cost is much lower than other NPMs. In this work, we report the formation of Pd-based NPM with improved catalytic activity towards the oxidation of glucose. By dealloying metallic glasses, Pd-based NPMs with bi-continuous networks were obtained. All the Pd-based NPMs show high electrochemical catalytic activity towards glucose oxidation. In this study, NPM with an open, three-dimensional, ligament-channel nanoporous structure resulted by dealloying metallic Pd30Cu40Ni10P20, producing a pore size of 11 nm and a ligament size of 7 nm as the best configuration towards the direct oxidation reaction of glucose.
2014, 25(4): 501-504
doi: 10.1016/j.cclet.2013.11.050
Abstract:
A series of substituted para-, meta- and ortho-nitrophenyl derivatives of fulleropyrrolidine were synthesized to investigate the effects of the position of substitution on electronic properties by using steady-state absorption and fluorescence spectra, combined with DFT calculations. The results confirmed that the position of substitution has little effect on absorption and fluorescence spectra, whereas a significant effect was observed on their LUMO energy levels. The theoretical calculations revealed that the LUMO energy of the ortho-nitrophenyl substituted derivative was increased 0.1 eV above those of para- and meta-substitution. The prominent effect of ortho-substitution was attributed to the through-space orbital interaction between spatially closed electron-withdrawing nitro group and fullerene cage. These findings could provide fundamental insights in raising LUMO levels of C60-based electron acceptor materials and an alternative strategy to increase open circuit voltage Voc in polymer solar cells.
A series of substituted para-, meta- and ortho-nitrophenyl derivatives of fulleropyrrolidine were synthesized to investigate the effects of the position of substitution on electronic properties by using steady-state absorption and fluorescence spectra, combined with DFT calculations. The results confirmed that the position of substitution has little effect on absorption and fluorescence spectra, whereas a significant effect was observed on their LUMO energy levels. The theoretical calculations revealed that the LUMO energy of the ortho-nitrophenyl substituted derivative was increased 0.1 eV above those of para- and meta-substitution. The prominent effect of ortho-substitution was attributed to the through-space orbital interaction between spatially closed electron-withdrawing nitro group and fullerene cage. These findings could provide fundamental insights in raising LUMO levels of C60-based electron acceptor materials and an alternative strategy to increase open circuit voltage Voc in polymer solar cells.
2014, 25(4): 505-510
doi: 10.1016/j.cclet.2014.01.028
Abstract:
A simple and sensitive platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene) nanocomposite (PtNPs/PEDOT-MeOH) modified glassy carbon electrode (GCE) was successfully developed for the electrochemical determination of quercetin. Scanning electron microscopy and energy dispersive X-ray spectroscopy results indicated that the PtNPs were inserted into the PEDOTMeOH layer. Compared with the bare GCE and poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes, the PtNPs/PEDOT-MeOH/GCE modified electrode exhibited a higher electrocatalytic ability toward the oxidation of quercetin due to the synergic effects of the electrocatalytic activity and strong adsorption ability of PtNPs together with the good water solubility and high conductivity of PEDOT-MeOH. The electrochemical sensor can be applied to the quantification of quercetin with a linear range covering 0.04-91 μmol L-1 and a low detection limit of 5.2 nmol L-1. Furthermore, the modified electrode also exhibited good reproducibility and long-term stability, as well as high selectivity.
A simple and sensitive platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene) nanocomposite (PtNPs/PEDOT-MeOH) modified glassy carbon electrode (GCE) was successfully developed for the electrochemical determination of quercetin. Scanning electron microscopy and energy dispersive X-ray spectroscopy results indicated that the PtNPs were inserted into the PEDOTMeOH layer. Compared with the bare GCE and poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes, the PtNPs/PEDOT-MeOH/GCE modified electrode exhibited a higher electrocatalytic ability toward the oxidation of quercetin due to the synergic effects of the electrocatalytic activity and strong adsorption ability of PtNPs together with the good water solubility and high conductivity of PEDOT-MeOH. The electrochemical sensor can be applied to the quantification of quercetin with a linear range covering 0.04-91 μmol L-1 and a low detection limit of 5.2 nmol L-1. Furthermore, the modified electrode also exhibited good reproducibility and long-term stability, as well as high selectivity.
2014, 25(4): 511-516
doi: 10.1016/j.cclet.2014.01.004
Abstract:
A novel graphene oxide (GO) doped poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOTM) film has been achieved via one-step co-electrodeposition and utilized for electrochemical studies of indole-3-acetic acid (IAA). The incorporation of GO into PEDOTM film facilitated the electrocatalytic activity and exhibited a favorable interaction between the PEDOTM/GO film and the phytohormone during the oxidation of IAA. Under optimized conditions, differential pulse voltammetry and square wave voltammetry were used for the quantitative analysis of IAA, respectively, each exhibiting a wide linearity range from 0.6 μmol L-1 to 10 μmol L-1 and 0.05 μmol L-1 to 40 μmol L-1, good sensitivity with a low detection limit of 0.087 μmol L-1 and 0.033 μmol L-1, respectively, as well as good stability. With the notable advantages of a green, sensitive method, expeditious response and facile operation, the as-prepared PEDOTM/GO organic-inorganic composite film provides a promising platform for electrochemical studies of IAA.
A novel graphene oxide (GO) doped poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOTM) film has been achieved via one-step co-electrodeposition and utilized for electrochemical studies of indole-3-acetic acid (IAA). The incorporation of GO into PEDOTM film facilitated the electrocatalytic activity and exhibited a favorable interaction between the PEDOTM/GO film and the phytohormone during the oxidation of IAA. Under optimized conditions, differential pulse voltammetry and square wave voltammetry were used for the quantitative analysis of IAA, respectively, each exhibiting a wide linearity range from 0.6 μmol L-1 to 10 μmol L-1 and 0.05 μmol L-1 to 40 μmol L-1, good sensitivity with a low detection limit of 0.087 μmol L-1 and 0.033 μmol L-1, respectively, as well as good stability. With the notable advantages of a green, sensitive method, expeditious response and facile operation, the as-prepared PEDOTM/GO organic-inorganic composite film provides a promising platform for electrochemical studies of IAA.
2014, 25(4): 517-522
doi: 10.1016/j.cclet.2013.12.020
Abstract:
A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A (BPA) by using carboxylic group functionalized single-walled carbon nanotubes (f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene) (PC4) complex modified glassy carbon electrode (GCE) has been successfully developed. The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques. The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS (0.1 mol/L, pH 7.0). The surface morphology of the 3D network of composite filmis beneficial for the adsorption of analytes. Under the optimized conditions, the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L (R2 = 0.9989), with a limit of detection of 0.032 μmol/L (S/N = 3). The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of f-SWCNT and the extraordinary conductivity of PC4. Furthermore, the proposed modified electrode displays high stability and good reproducibility. The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.
A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A (BPA) by using carboxylic group functionalized single-walled carbon nanotubes (f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene) (PC4) complex modified glassy carbon electrode (GCE) has been successfully developed. The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques. The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS (0.1 mol/L, pH 7.0). The surface morphology of the 3D network of composite filmis beneficial for the adsorption of analytes. Under the optimized conditions, the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L (R2 = 0.9989), with a limit of detection of 0.032 μmol/L (S/N = 3). The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of f-SWCNT and the extraordinary conductivity of PC4. Furthermore, the proposed modified electrode displays high stability and good reproducibility. The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.
2014, 25(4): 523-528
doi: 10.1016/j.cclet.2014.01.029
Abstract:
Ultrathin films of diazoresin (DR)/single-walled carbon nanotube (SWNT) were fabricated on thioglycollic acid (TGA) decorated gold (Au) electrodes by the self-assembly method combined with the photocrosslinking technique. The electrochemical behavior of dopamine (DA) at the DR/SWNT modified electrodes was studied using the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Under the optimal conditions, a linear CV response to DA concentration from 1 μmol/L to 40 μmol/L was observed, and the detection limit of DA was 2.1×10-3 μmol/L via the DPV method in the presence of 10 μmol/L of uric acid (UA) or 2.5×10-3 μmol/L via the DPV method in the presence of 10 μmol/L of ascorbic acid (AA). Moreover, the modified electrodes exhibited good reproducibility and sensitivity, demonstrating its feasibility for analytical purposes.
Ultrathin films of diazoresin (DR)/single-walled carbon nanotube (SWNT) were fabricated on thioglycollic acid (TGA) decorated gold (Au) electrodes by the self-assembly method combined with the photocrosslinking technique. The electrochemical behavior of dopamine (DA) at the DR/SWNT modified electrodes was studied using the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Under the optimal conditions, a linear CV response to DA concentration from 1 μmol/L to 40 μmol/L was observed, and the detection limit of DA was 2.1×10-3 μmol/L via the DPV method in the presence of 10 μmol/L of uric acid (UA) or 2.5×10-3 μmol/L via the DPV method in the presence of 10 μmol/L of ascorbic acid (AA). Moreover, the modified electrodes exhibited good reproducibility and sensitivity, demonstrating its feasibility for analytical purposes.
2014, 25(4): 529-531
doi: 10.1016/j.cclet.2014.01.030
Abstract:
Hexagonal trumpet-like sodium hexafluorosilicate (SFS) flowers, grown on an ordered porous polystyrene film (OPPF), were prepared via a synchronous dissolution/regrowth process. Their formation process can be divided into several steps: first, the dissolution of the silica spheres induced the crystallization of SFS onto the OPPF; second, some pores emerged on the closely packed bumpswhen being blown by the SiF4 gas; third, when the crystal was blown by continuous gas from the pores, the span of the top became larger than that of the bottom.
Hexagonal trumpet-like sodium hexafluorosilicate (SFS) flowers, grown on an ordered porous polystyrene film (OPPF), were prepared via a synchronous dissolution/regrowth process. Their formation process can be divided into several steps: first, the dissolution of the silica spheres induced the crystallization of SFS onto the OPPF; second, some pores emerged on the closely packed bumpswhen being blown by the SiF4 gas; third, when the crystal was blown by continuous gas from the pores, the span of the top became larger than that of the bottom.
2014, 25(4): 532-534
doi: 10.1016/j.cclet.2014.01.035
Abstract:
A convenient and efficient protocol for the synthesis of unnatural N-glycosyl α-amino acids was developed. Condensation of 1,3,4,6-tetra-O-actyl-β-D-glucosamine hydrochloride, alkenyl boronic acid, and glyoxylic acid was achieved in CH2Cl2 to give the derivatives of 2-(N-glycosyl)aminobut-3-enoic acid which may find applications in glycobiology research and medicinal chemistry.
A convenient and efficient protocol for the synthesis of unnatural N-glycosyl α-amino acids was developed. Condensation of 1,3,4,6-tetra-O-actyl-β-D-glucosamine hydrochloride, alkenyl boronic acid, and glyoxylic acid was achieved in CH2Cl2 to give the derivatives of 2-(N-glycosyl)aminobut-3-enoic acid which may find applications in glycobiology research and medicinal chemistry.
2014, 25(4): 535-540
doi: 10.1016/j.cclet.2014.01.034
Abstract:
Enantioselective synthesis of functionalized fluorinated dihydropyrano[2,3-c]pyrazoles has been achieved via a diaminocyclohexane-thiourea catalyzed cascade Michael addition and Thorpe-Ziegler type cyclization in high yields (up to 98%) with moderate to good enantioselectivity (up to 90% ee).
Enantioselective synthesis of functionalized fluorinated dihydropyrano[2,3-c]pyrazoles has been achieved via a diaminocyclohexane-thiourea catalyzed cascade Michael addition and Thorpe-Ziegler type cyclization in high yields (up to 98%) with moderate to good enantioselectivity (up to 90% ee).
2014, 25(4): 541-544
doi: 10.1016/j.cclet.2014.01.041
Abstract:
One new 6,7-seco-ent-kaurane diterpenoid, sculponin T (1), was isolated from the aerial parts of Isodon sculponeatus, along with four known analogs, sculponeatin J (2), sculponeatin K (3), sculponeatin C (4), and sculponeatin Q (5). Their structures were elucidated by extensive spectroscopic analysis and by comparison with data reported in the literature. Significant cytotoxic activity was observed for compound 2 against five human tumor cell lines with IC50 values ranging from 1.8 μmol/L to 3.3 μmol/L, and it also inhibited NO production in LPS-stimulated RAW264.7 cells, with IC50 value of 3.3 μmol/L.
One new 6,7-seco-ent-kaurane diterpenoid, sculponin T (1), was isolated from the aerial parts of Isodon sculponeatus, along with four known analogs, sculponeatin J (2), sculponeatin K (3), sculponeatin C (4), and sculponeatin Q (5). Their structures were elucidated by extensive spectroscopic analysis and by comparison with data reported in the literature. Significant cytotoxic activity was observed for compound 2 against five human tumor cell lines with IC50 values ranging from 1.8 μmol/L to 3.3 μmol/L, and it also inhibited NO production in LPS-stimulated RAW264.7 cells, with IC50 value of 3.3 μmol/L.
2014, 25(4): 545-548
doi: 10.1016/j.cclet.2014.01.021
Abstract:
Mediated by visible light-induced photoredox catalysis and free of other catalysts, a new and efficient synthesis of methylene-bridged bis-1,3-dicarbonyl derivatives has been developed. A variety of N-methyl tertiaryamines and 1,3-dicarbonyl compounds were investigated in this reaction.
Mediated by visible light-induced photoredox catalysis and free of other catalysts, a new and efficient synthesis of methylene-bridged bis-1,3-dicarbonyl derivatives has been developed. A variety of N-methyl tertiaryamines and 1,3-dicarbonyl compounds were investigated in this reaction.
2014, 25(4): 549-552
doi: 10.1016/j.cclet.2014.01.017
Abstract:
An efficient synthesis of substituted 1,3-dihydroisobenzofurans is developed. In this novel route, o-aroylbenzaldehydes, as key intermediates, can be obtained by lead tetraacetate oxidation of N-aroylhydrazones of salicylaldehydes. The mild and general strategy enables the synthesis of various substituted 1,3-dihydroisobenzofurans in high yields. Moreover, this method can be applied to efficiently synthesize escitalopram.
An efficient synthesis of substituted 1,3-dihydroisobenzofurans is developed. In this novel route, o-aroylbenzaldehydes, as key intermediates, can be obtained by lead tetraacetate oxidation of N-aroylhydrazones of salicylaldehydes. The mild and general strategy enables the synthesis of various substituted 1,3-dihydroisobenzofurans in high yields. Moreover, this method can be applied to efficiently synthesize escitalopram.
2014, 25(4): 553-556
doi: 10.1016/j.cclet.2013.12.018
Abstract:
This work described a one-pot tandem three-component synthesis of 2,4,5-triaryl-2,4-dihydro-3H-1,2,4-triazol-3-ones using a simple reaction between phenylhydrazines, benzaldehydes and phenyl isocyanates under microwave irradiation and solvent-free conditions in good to excellent yields.
This work described a one-pot tandem three-component synthesis of 2,4,5-triaryl-2,4-dihydro-3H-1,2,4-triazol-3-ones using a simple reaction between phenylhydrazines, benzaldehydes and phenyl isocyanates under microwave irradiation and solvent-free conditions in good to excellent yields.
2014, 25(4): 557-560
doi: 10.1016/j.cclet.2013.12.008
Abstract:
Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids.
Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids.
2014, 25(4): 561-566
doi: 10.1016/j.cclet.2013.11.028
Abstract:
SrCl2 was found to be the most efficient cocatalyst for the acidic hydrolysis of methyl glycosides after 26 kinds of most representative metal salts were screened. The SrCl2-cocatalyzed acidic hydrolysis of methyl glycosides is highlighted by short reaction times, less byproducts and high yields. A possible mechanism for the SrCl2-cocatalyzed hydrolysis is also proposed.
SrCl2 was found to be the most efficient cocatalyst for the acidic hydrolysis of methyl glycosides after 26 kinds of most representative metal salts were screened. The SrCl2-cocatalyzed acidic hydrolysis of methyl glycosides is highlighted by short reaction times, less byproducts and high yields. A possible mechanism for the SrCl2-cocatalyzed hydrolysis is also proposed.
2014, 25(4): 567-570
doi: 10.1016/j.cclet.2014.01.015
Abstract:
Wehave previously found that several families of nonpolar short chain 11β-ethers and esters of estradiol are selective estrogen receptor modulators (SERMs). Surprisingly, the transformation from potent estrogen to anti-estrogen occurs when the 11β-side chain is increased slightly in length from four to five non-hydrogen atoms. To generate strong antagonists for preclinical development, we have synthesized other similar ER ligands with 11β-ethers and with an additional ethinyl group at the 17α-position in order to slow metabolism of the steroidal moiety. Here we report the synthesis and biological activity of two such compounds (11β-i-PrO-propyl and 11β-t-BuO-propyl ethers) with extremely strong antagonist activities.
Wehave previously found that several families of nonpolar short chain 11β-ethers and esters of estradiol are selective estrogen receptor modulators (SERMs). Surprisingly, the transformation from potent estrogen to anti-estrogen occurs when the 11β-side chain is increased slightly in length from four to five non-hydrogen atoms. To generate strong antagonists for preclinical development, we have synthesized other similar ER ligands with 11β-ethers and with an additional ethinyl group at the 17α-position in order to slow metabolism of the steroidal moiety. Here we report the synthesis and biological activity of two such compounds (11β-i-PrO-propyl and 11β-t-BuO-propyl ethers) with extremely strong antagonist activities.
2014, 25(4): 571-574
doi: 10.1016/j.cclet.2014.01.027
Abstract:
A series of N-base appended corroles and their manganese complexes were synthesized and their binding constants with three different nitrogenous ligands, triethylamine, N-methylimidazole and pyridine, were evaluated by spectroscopy. Kinetic studies indicated that the presence of appended Ndonor ligands may cause a significant enhancement of the rate of oxygen atom transfers (OAT) from (oxo)manganese(Ⅴ) corrole to alkene, and the stronger axial ligand binding has impact on the rate of the oxidation reaction. Turnover frequency (TOF) for the catalytic oxidation of alkenes by appended manganese corroles varies with the following ligand order: acetamido < pyridyl < imidazolyl. The influence of the external axial ligands on the catalytic epoxidation was investigated by using appended acetamido manganese corrole as catalyst, with the results revealing that N-methylimidazole gave the best enhancement on the yields of total oxidation products among the investigated nitrogenous ligands.
A series of N-base appended corroles and their manganese complexes were synthesized and their binding constants with three different nitrogenous ligands, triethylamine, N-methylimidazole and pyridine, were evaluated by spectroscopy. Kinetic studies indicated that the presence of appended Ndonor ligands may cause a significant enhancement of the rate of oxygen atom transfers (OAT) from (oxo)manganese(Ⅴ) corrole to alkene, and the stronger axial ligand binding has impact on the rate of the oxidation reaction. Turnover frequency (TOF) for the catalytic oxidation of alkenes by appended manganese corroles varies with the following ligand order: acetamido < pyridyl < imidazolyl. The influence of the external axial ligands on the catalytic epoxidation was investigated by using appended acetamido manganese corrole as catalyst, with the results revealing that N-methylimidazole gave the best enhancement on the yields of total oxidation products among the investigated nitrogenous ligands.
2014, 25(4): 575-578
doi: 10.1016/j.cclet.2013.11.022
Abstract:
Sulfonated poly(4-vinylpyridine) heteropolyacid salts acted as a heterogeneous catalyst to effectively catalyze the one-pot synthesis of β-amino carbonyl compounds via the Mannich reaction between aromatic aldehydes, aromatic ketone, and aromatic amines. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity.
Sulfonated poly(4-vinylpyridine) heteropolyacid salts acted as a heterogeneous catalyst to effectively catalyze the one-pot synthesis of β-amino carbonyl compounds via the Mannich reaction between aromatic aldehydes, aromatic ketone, and aromatic amines. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity.
Synthesis and electrochemical properties of a chiral silyl-substituted tetrathiafulvalene derivative
2014, 25(4): 579-582
doi: 10.1016/j.cclet.2014.01.018
Abstract:
A new chiral tetrathiafulvalene (TTF) derivative and related silyl-substituted 1,3-dithiole-2-(thi)one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure of the silyl-substituted 1,3-dithiole-2-one revealed the high degree of conjugation of the fivemembered ring moiety in the compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry and the results indicated that the electron-donating ability of the chiral TTF derivative was similar to that of BEDT-TTF. The ΔE value for the new TTF derivative was smaller than those for TTF and BEDT-TTF, indicative of decreased Coulombic repulsion in the dicationic redox state. Formation of charge-transfer (CT) complex between the new donor and electron acceptor 2,3-dichloro- 5,6-dicyano-1,4-benzoquinone (DDQ) was demonstrated.
A new chiral tetrathiafulvalene (TTF) derivative and related silyl-substituted 1,3-dithiole-2-(thi)one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure of the silyl-substituted 1,3-dithiole-2-one revealed the high degree of conjugation of the fivemembered ring moiety in the compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry and the results indicated that the electron-donating ability of the chiral TTF derivative was similar to that of BEDT-TTF. The ΔE value for the new TTF derivative was smaller than those for TTF and BEDT-TTF, indicative of decreased Coulombic repulsion in the dicationic redox state. Formation of charge-transfer (CT) complex between the new donor and electron acceptor 2,3-dichloro- 5,6-dicyano-1,4-benzoquinone (DDQ) was demonstrated.
2014, 25(4): 583-585
doi: 10.1016/j.cclet.2014.01.020
Abstract:
An efficient preparation of imidazolines from nitriles and aziridines in the presence of TfOH via Ritter reaction is described. It indicates that different kinds of nitriles can undergo the process. Among the nitriles, pivalonitrile is proven to be better than acetonitrile. The reaction is performed at room temperature and the yields are excellent.
An efficient preparation of imidazolines from nitriles and aziridines in the presence of TfOH via Ritter reaction is described. It indicates that different kinds of nitriles can undergo the process. Among the nitriles, pivalonitrile is proven to be better than acetonitrile. The reaction is performed at room temperature and the yields are excellent.
2014, 25(4): 586-588
doi: 10.1016/j.cclet.2014.01.049
Abstract:
Five organotin complexes of terpyridine derivatives were synthesized and characterized. The mononuclear Sn(Ⅳ) complexes were six-coordinated adopting a distorted octahedral coordination geometry. A brief outline of the fluorescence spectra and the in vitro cytotoxicity of the Sn(Ⅳ) complexes have been given.
Five organotin complexes of terpyridine derivatives were synthesized and characterized. The mononuclear Sn(Ⅳ) complexes were six-coordinated adopting a distorted octahedral coordination geometry. A brief outline of the fluorescence spectra and the in vitro cytotoxicity of the Sn(Ⅳ) complexes have been given.
2014, 25(4): 589-592
doi: 10.1016/j.cclet.2014.01.019
Abstract:
A new series of bis-benzimidazole derivatives were designed and synthesized. In vitro cytotoxicity evaluation showed that these compounds exhibited high activity against the selected tumor cells. Among them, compound 9 owned the best potential, its IC50 values being 5.95 μmol/L (mononuclear tumor cell line (U937)) and 5.58 μmol/L (cervical cancer cell (HeLa)). Fluorescence and UV-vis studies showed that compound 9 could bind into the minor groove of DNA.
A new series of bis-benzimidazole derivatives were designed and synthesized. In vitro cytotoxicity evaluation showed that these compounds exhibited high activity against the selected tumor cells. Among them, compound 9 owned the best potential, its IC50 values being 5.95 μmol/L (mononuclear tumor cell line (U937)) and 5.58 μmol/L (cervical cancer cell (HeLa)). Fluorescence and UV-vis studies showed that compound 9 could bind into the minor groove of DNA.
2014, 25(4): 593-595
doi: 10.1016/j.cclet.2014.01.005
Abstract:
The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione (1) in the presence of arylsulfinic acids (2a and 2b) as nucleophiles. The results show that, the electrogenerated phthalazine-1,4-dione (1ox) participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.
The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione (1) in the presence of arylsulfinic acids (2a and 2b) as nucleophiles. The results show that, the electrogenerated phthalazine-1,4-dione (1ox) participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.
2014, 25(4): 596-600
doi: 10.1016/j.cclet.2014.01.001
Abstract:
Both terminated functional isotactic polypropylene (iPP) and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hydroxyl-terminated isotactic polypropylene (iPP-t-OH) and functional di-block copolymer containing the iPP segment through a combination of coordination polymerization and coupling reaction. The coordination polymerization was catalyzed by TiCl4/MgCl2/AlEt3 catalyst system using ZnEt2 as chain transfer agent. Further, the Zn-terminated iPP was oxidized and subsequently hydrolyzed to provide iPP-t-OH. Soxhlet extraction and 13C NMR were used to calculate the isotacticity of iPP-t-OH. The degree of polymerization and the number of hydroxyl groups at the chain end of iPP-t-OH were measured by GPC and 1H NMR. Despite the high molecular weight and heterogeneous reaction, iPP-t-OH is effectively linked with PEG-t-NCO to produce di-block copolymers. DSC analysis of the di-block copolymer shows an obvious decrease in Tm and Tc, which indicated that PEG was successfully linked to the terminal end of iPP.
Both terminated functional isotactic polypropylene (iPP) and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hydroxyl-terminated isotactic polypropylene (iPP-t-OH) and functional di-block copolymer containing the iPP segment through a combination of coordination polymerization and coupling reaction. The coordination polymerization was catalyzed by TiCl4/MgCl2/AlEt3 catalyst system using ZnEt2 as chain transfer agent. Further, the Zn-terminated iPP was oxidized and subsequently hydrolyzed to provide iPP-t-OH. Soxhlet extraction and 13C NMR were used to calculate the isotacticity of iPP-t-OH. The degree of polymerization and the number of hydroxyl groups at the chain end of iPP-t-OH were measured by GPC and 1H NMR. Despite the high molecular weight and heterogeneous reaction, iPP-t-OH is effectively linked with PEG-t-NCO to produce di-block copolymers. DSC analysis of the di-block copolymer shows an obvious decrease in Tm and Tc, which indicated that PEG was successfully linked to the terminal end of iPP.
2014, 25(4): 601-604
doi: 10.1016/j.cclet.2014.01.031
Abstract:
The present studies highlight the effective removal of As(Ⅴ) and Cd(Ⅱ) from aqueous solutions by superabsorbent poly (NIPAAm/AA/N-allylisatin) nanohydrogel. Batch removal studies were performed as a function of treatment time, initial metal ion concentration, pH, and adsorbent dose. TEM micrographs confirm the particle size distribution in the range between 5 nmand 10 nm. The simple and metal ions adsorbed nanohydrogels were characterized by FT-IR, TGA, and EDX analysis. Finally, the equilibrium removal efficiency of the nanohydrogel was analyzed according to the Langmuir and Freundlich adsorption isotherm models which showed the removal of As(Ⅴ) and Cd(Ⅱ) metal ions fitted to Freundlich and Langmuir isotherms, respectively. Removal efficiency order of the metal ions is As(Ⅴ) > Cd(Ⅱ).
The present studies highlight the effective removal of As(Ⅴ) and Cd(Ⅱ) from aqueous solutions by superabsorbent poly (NIPAAm/AA/N-allylisatin) nanohydrogel. Batch removal studies were performed as a function of treatment time, initial metal ion concentration, pH, and adsorbent dose. TEM micrographs confirm the particle size distribution in the range between 5 nmand 10 nm. The simple and metal ions adsorbed nanohydrogels were characterized by FT-IR, TGA, and EDX analysis. Finally, the equilibrium removal efficiency of the nanohydrogel was analyzed according to the Langmuir and Freundlich adsorption isotherm models which showed the removal of As(Ⅴ) and Cd(Ⅱ) metal ions fitted to Freundlich and Langmuir isotherms, respectively. Removal efficiency order of the metal ions is As(Ⅴ) > Cd(Ⅱ).
2014, 25(4): 605-608
doi: 10.1016/j.cclet.2014.01.002
Abstract:
A phthalazinone monomer with an allyl group, i.e. 4-(3-allyl-4-hydroxyphenyl)phthalazin-1(2H)-one, was synthesized and then copolymerized with 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one and 2,6- diflurobenzonitrile by means of aromatic nucleophilic polycondensation to provide a series of crosslinkable poly(aryl ether nitrile)s. The virgin copolymers exhibited good solubility in polar organic solvents with relative high molecular weights (Mw: 45,130-58,403, inherent viscosities: 0.58-0.75 dL/g). After cross-linking, the thermal stability and solvent resistance of the polymer increased.
A phthalazinone monomer with an allyl group, i.e. 4-(3-allyl-4-hydroxyphenyl)phthalazin-1(2H)-one, was synthesized and then copolymerized with 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one and 2,6- diflurobenzonitrile by means of aromatic nucleophilic polycondensation to provide a series of crosslinkable poly(aryl ether nitrile)s. The virgin copolymers exhibited good solubility in polar organic solvents with relative high molecular weights (Mw: 45,130-58,403, inherent viscosities: 0.58-0.75 dL/g). After cross-linking, the thermal stability and solvent resistance of the polymer increased.
2014, 25(4): 609-612
doi: 10.1016/j.cclet.2014.01.016
Abstract:
The title compound exists as yellow (1Y) and red (1R) crystals, but both gave red solutions. The intermolecular interactions between the CN parts of the crystals in 1Y are very weak. By the mechanical crushing as well as in solution 1Y again becomes red due to the absence of intermolecular interactions. We explain this color behavior by crystallochromism and solvation chromism.
The title compound exists as yellow (1Y) and red (1R) crystals, but both gave red solutions. The intermolecular interactions between the CN parts of the crystals in 1Y are very weak. By the mechanical crushing as well as in solution 1Y again becomes red due to the absence of intermolecular interactions. We explain this color behavior by crystallochromism and solvation chromism.
2014, 25(4): 613-616
doi: 10.1016/j.cclet.2014.01.007
Abstract:
A chiral catalyst, Cp*RhTsDPEN (Cp* = pentamethyl cyclopentadiene, TsDPEN = substitutive phenylsulfonyl-1,2-diphenylethylenediamine), was synthesized and immobilized at the surface of glass. The immobilized catalyst exhibited good catalytic efficiency for asymmetric transfer hydrogenation of aromatic ketones in water with HCOONa as hydrogen source.
A chiral catalyst, Cp*RhTsDPEN (Cp* = pentamethyl cyclopentadiene, TsDPEN = substitutive phenylsulfonyl-1,2-diphenylethylenediamine), was synthesized and immobilized at the surface of glass. The immobilized catalyst exhibited good catalytic efficiency for asymmetric transfer hydrogenation of aromatic ketones in water with HCOONa as hydrogen source.
2014, 25(4): 617-620
doi: 10.1016/j.cclet.2013.12.012
Abstract:
The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100 kHz (interval by 20 kHz) and 10-50W (interval by 10 W), respectively. The experimental data indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.
The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100 kHz (interval by 20 kHz) and 10-50W (interval by 10 W), respectively. The experimental data indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.
2014, 25(4): 621-626
doi: 10.1016/j.cclet.2013.12.021
Abstract:
Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane (D4) in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassium hydrate as an initiator. The particle size was determined by the dynamic light scattering (DLS) technique and the reaction rates of the polymerization were discussed. Furthermore, the kinetics was studied by an initial-rate method, and the effects of the monomer, emulsifier and initiator concentrations and the temperature on polymerization conversions were investigated. From the kinetic results, the rate of polymerization, Rp at 80℃ can be expressed as Rp=k[D4]0.79[OTAC]0.64[KOH]0.38 and the apparent activation energy (Ea), which was determined by half-period method, is 95.32 kJ mol-1.
Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane (D4) in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassium hydrate as an initiator. The particle size was determined by the dynamic light scattering (DLS) technique and the reaction rates of the polymerization were discussed. Furthermore, the kinetics was studied by an initial-rate method, and the effects of the monomer, emulsifier and initiator concentrations and the temperature on polymerization conversions were investigated. From the kinetic results, the rate of polymerization, Rp at 80℃ can be expressed as Rp=k[D4]0.79[OTAC]0.64[KOH]0.38 and the apparent activation energy (Ea), which was determined by half-period method, is 95.32 kJ mol-1.
2014, 25(4): 627-629
doi: 10.1016/j.cclet.2014.01.043
Abstract:
Hollow silica microspheres (HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor. The resulting silica hollow particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and infrared spectroscopy (IR). The surface area was determined using the BET method. SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5 μm.
Hollow silica microspheres (HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor. The resulting silica hollow particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and infrared spectroscopy (IR). The surface area was determined using the BET method. SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5 μm.
2014, 25(4): 630-634
doi: 10.1016/j.cclet.2014.01.022
Abstract:
Removing excessive free radicals (FRs) by a synthetic chemical might give a clue for treatment of many iron-mediated diseases. Deferoxamine (DFO) can be one of the chemicals of choice for the clue. To investigate photoredox properties of DFO, its quenching effect on superoxide radical (O2-·), hydrogen peroxide (H2O2) and hydroxyl radical (OH·) was examined using luminol and ortho-phenanthroline (o-phen) chemiluminescence (CL) systems and UV-vis spectrophotometry. Stern-Volmer equation was also used for the CL kinetics. The observed quenching effect of DFO on CL/photon production in luminol and o-phen CL systems strongly confirmed the static arm of quenching properties of DFO on OH· and H2O2, but much less pronounced on O2-·; the quenching property wasmaximal when iron was involved in the reaction systems. The Stern-Volmer plots in the designed photochemical reaction systems also confirmed a potent quenching effect of DFO on FR-mediated CL. Our study highlights strong photoreducing and antioxidant properties of DFO with huge quenching capacity on excessive FRs, and thus implies its promising prospects for therapeutic applications.
Removing excessive free radicals (FRs) by a synthetic chemical might give a clue for treatment of many iron-mediated diseases. Deferoxamine (DFO) can be one of the chemicals of choice for the clue. To investigate photoredox properties of DFO, its quenching effect on superoxide radical (O2-·), hydrogen peroxide (H2O2) and hydroxyl radical (OH·) was examined using luminol and ortho-phenanthroline (o-phen) chemiluminescence (CL) systems and UV-vis spectrophotometry. Stern-Volmer equation was also used for the CL kinetics. The observed quenching effect of DFO on CL/photon production in luminol and o-phen CL systems strongly confirmed the static arm of quenching properties of DFO on OH· and H2O2, but much less pronounced on O2-·; the quenching property wasmaximal when iron was involved in the reaction systems. The Stern-Volmer plots in the designed photochemical reaction systems also confirmed a potent quenching effect of DFO on FR-mediated CL. Our study highlights strong photoreducing and antioxidant properties of DFO with huge quenching capacity on excessive FRs, and thus implies its promising prospects for therapeutic applications.
2014, 25(4): 635-639
doi: 10.1016/j.cclet.2014.01.036
Abstract:
In this study, a method based on low temperature purification (LTP) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of abamectin (ABA) and ivermectin (IVR) in edible oils. ABA and IVR were extracted using conventional liquid-liquid extraction followed by purification via precipitation of interfering fatty components at low temperature without an additional cleanup step. LTP is simple, easy to use, labour-saving and cost effective, and requires reduced amounts of organic solvent. The linear ranges of ABA and IVR were 5- 1000 μg/L using matrix-matched standards. Limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.1-0.4 μg/kg and 0.3-1.3 μg/kg, respectively. The LOQs were below the strictest maximum residue limits established by Codex Alimentarius Commission. Recoveries at three spiked levels of 10, 20 and 100 μg/kg in peanut oil, corn oil, olive oil, soybean oil and lard ranged from 71.1% to 119.3% with relative standard deviations of 3.2%-10.3%, which were in agreement with those obtained by the solid phase extraction method. The proposed method was utilized in the analysis of 10 edible oil samples from localmarket and neither ABA nor IVR was detected. As far as we know, this is the first time that LTP is applied to the determination of avermectins in edible oils.
In this study, a method based on low temperature purification (LTP) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of abamectin (ABA) and ivermectin (IVR) in edible oils. ABA and IVR were extracted using conventional liquid-liquid extraction followed by purification via precipitation of interfering fatty components at low temperature without an additional cleanup step. LTP is simple, easy to use, labour-saving and cost effective, and requires reduced amounts of organic solvent. The linear ranges of ABA and IVR were 5- 1000 μg/L using matrix-matched standards. Limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.1-0.4 μg/kg and 0.3-1.3 μg/kg, respectively. The LOQs were below the strictest maximum residue limits established by Codex Alimentarius Commission. Recoveries at three spiked levels of 10, 20 and 100 μg/kg in peanut oil, corn oil, olive oil, soybean oil and lard ranged from 71.1% to 119.3% with relative standard deviations of 3.2%-10.3%, which were in agreement with those obtained by the solid phase extraction method. The proposed method was utilized in the analysis of 10 edible oil samples from localmarket and neither ABA nor IVR was detected. As far as we know, this is the first time that LTP is applied to the determination of avermectins in edible oils.
2014, 25(4): 640-644
doi: 10.1016/j.cclet.2014.01.037
Abstract:
A hollow-fiber liquid-phasemicroextraction (HF-LPME) method has been developed for the purification and preconcentration of biogenic polyamines and their precursor amino acids in human saliva. Putrescine (Put), cadaverine (Cad), spermidine (Spe), ornithine (Orn), lysine (Lys), and arginine (Arg) were determined by the CE-LIF detection after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, six analytes could achieve baseline separation within 30 min, exhibiting a linear calibration at three orders of magnitude (r2 > 0.998); the obtained enrichment factors of HF-LPME were between 19 (for Orn) and 218 (for Cad), and the LODs were in the range of 0.0072-0.26 nmol/L. The proposed HF-LPME/CE-LIF method has been successfully applied for the sensitive analyses of the real-world saliva samples collected from healthy volunteers and different patients with oral diseases, providing a potential method for primary non-invasive diagnosis of some oral diseases.
A hollow-fiber liquid-phasemicroextraction (HF-LPME) method has been developed for the purification and preconcentration of biogenic polyamines and their precursor amino acids in human saliva. Putrescine (Put), cadaverine (Cad), spermidine (Spe), ornithine (Orn), lysine (Lys), and arginine (Arg) were determined by the CE-LIF detection after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, six analytes could achieve baseline separation within 30 min, exhibiting a linear calibration at three orders of magnitude (r2 > 0.998); the obtained enrichment factors of HF-LPME were between 19 (for Orn) and 218 (for Cad), and the LODs were in the range of 0.0072-0.26 nmol/L. The proposed HF-LPME/CE-LIF method has been successfully applied for the sensitive analyses of the real-world saliva samples collected from healthy volunteers and different patients with oral diseases, providing a potential method for primary non-invasive diagnosis of some oral diseases.
2014, 25(4): 645-648
doi: 10.1016/j.cclet.2013.11.032
Abstract:
We demonstrate that Mo6S9-xIx nanowires (MoSI NWs) can serve as an excellent signal-intensifying nanomaterial for highly sensitive and label-free detection of DNA by ultraviolet (UV) spectrophotometry. The DNA extinction at 260 nm was greatly enhanced after addition of MoSI NWs solute, and the extinction value was linear with DNA concentration in the range of 0.0289-11.68 μg/mL with the real determination limit of 28.9 ng/mL. The association of DNA with the nanowires was characterized by transmission electronmicroscopy and circular dichroic spectroscopy. The results illustrate that the UV response amplification of DNA in the presence of MoSI NWs is attributed to the greater DNA coverage on the MoSINWsurface and the conformational transformation of DNA due to interaction of DNA with MoSI NWs. MoSI NWs are a promising nano-structured material for developing ultrasensitive sensors for detection of DNA.
We demonstrate that Mo6S9-xIx nanowires (MoSI NWs) can serve as an excellent signal-intensifying nanomaterial for highly sensitive and label-free detection of DNA by ultraviolet (UV) spectrophotometry. The DNA extinction at 260 nm was greatly enhanced after addition of MoSI NWs solute, and the extinction value was linear with DNA concentration in the range of 0.0289-11.68 μg/mL with the real determination limit of 28.9 ng/mL. The association of DNA with the nanowires was characterized by transmission electronmicroscopy and circular dichroic spectroscopy. The results illustrate that the UV response amplification of DNA in the presence of MoSI NWs is attributed to the greater DNA coverage on the MoSINWsurface and the conformational transformation of DNA due to interaction of DNA with MoSI NWs. MoSI NWs are a promising nano-structured material for developing ultrasensitive sensors for detection of DNA.
2014, 25(4): 649-654
doi: 10.1016/j.cclet.2013.12.025
Abstract:
In the present work, an easy solid phase extraction method using alumina modified with polyethylenimine as a new adsorbent was applied to the simultaneous extraction of copper, silver, and palladium ions prior to their determination with electrothermal atomic absorption spectrometry. The analytical procedure involved the complex formation of these cations with polyethylenimine as a chelating agent in buffer media of pH 7.0. Under the optimum conditions, a preconcentration factor of 200, 150, and 200, precision of ±5.4%, ±4.7%, and ±5.2% and linear calibration ranges of 15.0-140, 4.0-93, and 7.5-125 ng/L (in original solution) for Cu, Ag, and Pd were obtained, respectively. Also detection limits of 3.9, 1.1, and 2.0 ng/L were obtained for Cu, Ag, and Pd, respectively. The proposed method was applied to the determination of copper, silver, and palladium in some real samples with satisfactory results.
In the present work, an easy solid phase extraction method using alumina modified with polyethylenimine as a new adsorbent was applied to the simultaneous extraction of copper, silver, and palladium ions prior to their determination with electrothermal atomic absorption spectrometry. The analytical procedure involved the complex formation of these cations with polyethylenimine as a chelating agent in buffer media of pH 7.0. Under the optimum conditions, a preconcentration factor of 200, 150, and 200, precision of ±5.4%, ±4.7%, and ±5.2% and linear calibration ranges of 15.0-140, 4.0-93, and 7.5-125 ng/L (in original solution) for Cu, Ag, and Pd were obtained, respectively. Also detection limits of 3.9, 1.1, and 2.0 ng/L were obtained for Cu, Ag, and Pd, respectively. The proposed method was applied to the determination of copper, silver, and palladium in some real samples with satisfactory results.
2014, 25(4): 655-658
doi: 10.1016/j.cclet.2014.01.014
Abstract:
A simple and rapid protocol for the synthesis of polystyrene-graphene oxide nanocomposite (PS/GONC) was achieved for first time using an in situ polymerization method. PS/GONC modified glassy carbon electrode (PS/GONC/GCE) has been employed as an efficient nanosensor for the electrooxidation of histamine. The PS/GONC/GCE is used as an electrochemical nanosensors for monitoring histamine using differential pulse voltammetry techniques (detection limit 0.03 μmol/L). In addition, the prepared nanosensor was successfully applied to determine histamine in fish samples, yielding satisfactory results. The spiked recoveries were in the range of 98.2%-103.1%.
A simple and rapid protocol for the synthesis of polystyrene-graphene oxide nanocomposite (PS/GONC) was achieved for first time using an in situ polymerization method. PS/GONC modified glassy carbon electrode (PS/GONC/GCE) has been employed as an efficient nanosensor for the electrooxidation of histamine. The PS/GONC/GCE is used as an electrochemical nanosensors for monitoring histamine using differential pulse voltammetry techniques (detection limit 0.03 μmol/L). In addition, the prepared nanosensor was successfully applied to determine histamine in fish samples, yielding satisfactory results. The spiked recoveries were in the range of 98.2%-103.1%.
