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2010 Volume 21 Issue 6
2010, 21(6): 633-636
doi: 10.1016/j.cclet.2010.01.028
Abstract:
Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by 1H NMR, 13C NMR, MALDI-TOF-MS and elemental analysis. X-ray diffraction analysis of the solid state molecular structure showed that the complex units are linked by non-classical C-H…F hydrogen bonding.
Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by 1H NMR, 13C NMR, MALDI-TOF-MS and elemental analysis. X-ray diffraction analysis of the solid state molecular structure showed that the complex units are linked by non-classical C-H…F hydrogen bonding.
2010, 21(6): 637-640
doi: 10.1016/j.cclet.2010.01.023
Abstract:
A homologous series of Schiff base esters, 4-chlorobenzylidene-4'-n-alkanoyloxyanilines, containing even number of carbons at the end groups of the molecules (Cn-1H2n-1COO-, n=4,6,8,10,12,14,16) were synthesized. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). It was found that the end groups of the molecules had an effect on the mesomorphic properties. n-Butanoyloxy was found non-mesogenic, whilst n-hexanoyloxy exhibited monotropic smectic phase. The higher members in this homologous series were enantiotropic smectogens.
A homologous series of Schiff base esters, 4-chlorobenzylidene-4'-n-alkanoyloxyanilines, containing even number of carbons at the end groups of the molecules (Cn-1H2n-1COO-, n=4,6,8,10,12,14,16) were synthesized. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). It was found that the end groups of the molecules had an effect on the mesomorphic properties. n-Butanoyloxy was found non-mesogenic, whilst n-hexanoyloxy exhibited monotropic smectic phase. The higher members in this homologous series were enantiotropic smectogens.
2010, 21(6): 641-645
doi: 10.1016/j.cclet.2010.01.042
Abstract:
Suzuki reaction of bromoallenes with arylboronic acids was successfully performed by using an air-stable hemilabile P-O coordinated cyclopalladated complex Pd(PH2PCH2CH2)2 as a precatalyst, and the corresponding coupling products were obtained in satisfactory to excellent yields. All products are unknown compounds which were characterized by 1H NMR, 13C NMR, IR, and HRMS.
Suzuki reaction of bromoallenes with arylboronic acids was successfully performed by using an air-stable hemilabile P-O coordinated cyclopalladated complex Pd(PH2PCH2CH2)2 as a precatalyst, and the corresponding coupling products were obtained in satisfactory to excellent yields. All products are unknown compounds which were characterized by 1H NMR, 13C NMR, IR, and HRMS.
2010, 21(6): 646-650
doi: 10.1016/j.cclet.2010.01.003
Abstract:
A new series of fatty alkenoates were synthesized using an appropriate synthetic route involving DCC and DMAP as catalysts. Compounds were characterized by their spectral data. All the synthesized compounds were evaluated for their in vitro antimicrobial activity. The minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC) and minimum fungicidal concentration (MFC) were determined for test compounds as well as for reference standards. Among the compounds tested, compounds having hydroxy group at the fatty acid chain showed the most potent antibacterial as well as antifungal activities.
A new series of fatty alkenoates were synthesized using an appropriate synthetic route involving DCC and DMAP as catalysts. Compounds were characterized by their spectral data. All the synthesized compounds were evaluated for their in vitro antimicrobial activity. The minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC) and minimum fungicidal concentration (MFC) were determined for test compounds as well as for reference standards. Among the compounds tested, compounds having hydroxy group at the fatty acid chain showed the most potent antibacterial as well as antifungal activities.
2010, 21(6): 651-655
doi: 10.1016/j.cclet.2010.01.004
Abstract:
DBUH-Br3 catalyzed selective conversion of sulfides to sulfoxides in the presence of H2O2 as oxidizing agent is described. The reaction was performed selectively at room temperature and relatively short reaction times.
DBUH-Br3 catalyzed selective conversion of sulfides to sulfoxides in the presence of H2O2 as oxidizing agent is described. The reaction was performed selectively at room temperature and relatively short reaction times.
2010, 21(6): 656-660
doi: 10.1016/j.cclet.2010.01.010
Abstract:
The palladium-salen complex palladium (Ⅱ) N,N'-bis {[5-(triphenylphosphonium)-methyl]salicylidene}-l,2-ethanediamine chloride was found to be a highly active catalyst for the copper-and solvent-free coupling reaction of terminal alkynes with different acyl chlorides in the presence of triethylamine as base, giving excellent ynones under aerobic conditions.
The palladium-salen complex palladium (Ⅱ) N,N'-bis {[5-(triphenylphosphonium)-methyl]salicylidene}-l,2-ethanediamine chloride was found to be a highly active catalyst for the copper-and solvent-free coupling reaction of terminal alkynes with different acyl chlorides in the presence of triethylamine as base, giving excellent ynones under aerobic conditions.
2010, 21(6): 661-663
doi: 10.1016/j.cclet.2010.01.037
Abstract:
Five C3/C3 fluoroquinolone dimers tethered with a fused heterocyclic ring of s-triazolo[2,1-b] [1,3,4]thiadiazole derived from antibacterial quinolones were synthesized and characterized, and their in vitro antitumor activity against L1210, CHO cell lines was evaluated via the respective IC50 values.
Five C3/C3 fluoroquinolone dimers tethered with a fused heterocyclic ring of s-triazolo[2,1-b] [1,3,4]thiadiazole derived from antibacterial quinolones were synthesized and characterized, and their in vitro antitumor activity against L1210, CHO cell lines was evaluated via the respective IC50 values.
2010, 21(6): 664-668
doi: 10.1016/j.cclet.2010.01.038
Abstract:
A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition. Macroporous strongly acidic styrol resin (D001) as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions. The pyrroles were obtained in high yields in short reaction times.
A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition. Macroporous strongly acidic styrol resin (D001) as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions. The pyrroles were obtained in high yields in short reaction times.
2010, 21(6): 669-673
doi: 10.1016/j.cclet.2009.12.010
Abstract:
Reactions of the 6-hydroxy-thiopyrano [3,4-c]pyridine-5-carbonitrile derivative 1 with α-halo-carbonyl compounds gave the ortho-substituted intermediates 2a-c which were converted into furo [2,3-b]thiopyrano [4,3-d]pyridines 3a-c by fusion of a furan moiety under basic conditions. Further cyclization of 3a-c led to a fusion of a pyrimidine ring, yielding the tetracyclic products 6,7 and 8. In addition, condensation of 6 with various aromatic aldehydes afforded the corresponding imines 9a,b. Mannich reaction of 7 gave products 10a,b.
Reactions of the 6-hydroxy-thiopyrano [3,4-c]pyridine-5-carbonitrile derivative 1 with α-halo-carbonyl compounds gave the ortho-substituted intermediates 2a-c which were converted into furo [2,3-b]thiopyrano [4,3-d]pyridines 3a-c by fusion of a furan moiety under basic conditions. Further cyclization of 3a-c led to a fusion of a pyrimidine ring, yielding the tetracyclic products 6,7 and 8. In addition, condensation of 6 with various aromatic aldehydes afforded the corresponding imines 9a,b. Mannich reaction of 7 gave products 10a,b.
2010, 21(6): 674-677
doi: 10.1016/j.cclet.2010.02.001
Abstract:
The catalytic activity of Fe/ZSM-5 for the selective reduction of NO to N2 with methane in the presence of excess O2 was studied. Fe/ZSM-5 catalysts with various Fe loadings were prepared by impregnation method. It is well known that methane is inactive when Fe/ZSM-5 as the catalyst for the selective catalytic reduction (SCR) of NO with methane. However, this paper shows that when the content of Fe was about 0.5%, Fe/ZSM-5 showed higher catalytic activity and selectivity of methane, and put forward measurable activation for CH4 is an important factor for the reaction of removal of NOx with CH4.
The catalytic activity of Fe/ZSM-5 for the selective reduction of NO to N2 with methane in the presence of excess O2 was studied. Fe/ZSM-5 catalysts with various Fe loadings were prepared by impregnation method. It is well known that methane is inactive when Fe/ZSM-5 as the catalyst for the selective catalytic reduction (SCR) of NO with methane. However, this paper shows that when the content of Fe was about 0.5%, Fe/ZSM-5 showed higher catalytic activity and selectivity of methane, and put forward measurable activation for CH4 is an important factor for the reaction of removal of NOx with CH4.
2010, 21(6): 678-681
doi: 10.1016/j.cclet.2010.02.004
Abstract:
[Hmim]3PW12O40 was developed and used in the acetalization of carbonyl compounds in excellent yields. The ionic liquid-heteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation. The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
[Hmim]3PW12O40 was developed and used in the acetalization of carbonyl compounds in excellent yields. The ionic liquid-heteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation. The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
2010, 21(6): 682-685
doi: 10.1016/j.cclet.2009.12.020
Abstract:
The synthesis and mesomorphic properties of a new class of liquid crystalline cyclotriphosphazenes with rigid cyanostilbene groups and flexible alkoxy groups are reported. The thermal behaviors of cyclotriphosphazene derivatives 5a-5d are studied by the means of differential scanning calorimetry, polarizing optical microscopy. Nematic phases were observed in compounds 5a-5d both on heating and cooling. The clear temperatures of compounds 5a-5d slightly increased with increasing length of terminal alkyl chain. Compounds 5a-5d showed different mesogenic region from minimum 5℃ to maximum 142℃.
The synthesis and mesomorphic properties of a new class of liquid crystalline cyclotriphosphazenes with rigid cyanostilbene groups and flexible alkoxy groups are reported. The thermal behaviors of cyclotriphosphazene derivatives 5a-5d are studied by the means of differential scanning calorimetry, polarizing optical microscopy. Nematic phases were observed in compounds 5a-5d both on heating and cooling. The clear temperatures of compounds 5a-5d slightly increased with increasing length of terminal alkyl chain. Compounds 5a-5d showed different mesogenic region from minimum 5℃ to maximum 142℃.
2010, 21(6): 686-689
doi: 10.1016/j.cclet.2010.02.005
Abstract:
2,2'-Arylmethylene bis (3-hydroxy-5,5-dimethyl-2-cycIohexene-l-one) 41-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst; whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.
2,2'-Arylmethylene bis (3-hydroxy-5,5-dimethyl-2-cycIohexene-l-one) 41-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst; whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.
2010, 21(6): 690-692
doi: 10.1016/j.cclet.2010.02.002
Abstract:
A new kaempferol glycoside, named kaempferol 3-O-[6"-O-β-D-glucopyranosyl-6'''-O-α-L-rhamnopy ranosyl-2""-O-α-L-rharnnopyranosyl]-β-D-glucopyranoside, was isolated from Hydrangea macrophylla (Thunb.) Seringe. Its structure was established by spectroscopic techniques including MS, IR, UV, and 2D NMR.
A new kaempferol glycoside, named kaempferol 3-O-[6"-O-β-D-glucopyranosyl-6'''-O-α-L-rhamnopy ranosyl-2""-O-α-L-rharnnopyranosyl]-β-D-glucopyranoside, was isolated from Hydrangea macrophylla (Thunb.) Seringe. Its structure was established by spectroscopic techniques including MS, IR, UV, and 2D NMR.
2010, 21(6): 693-695
doi: 10.1016/j.cclet.2010.01.009
Abstract:
Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica, along with the known 6-O-β-E-p-coumaroyl-4α-hydroxyeudesmane (1). Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane (2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesrnane (3) by spectroscopic methods.
Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica, along with the known 6-O-β-E-p-coumaroyl-4α-hydroxyeudesmane (1). Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane (2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesrnane (3) by spectroscopic methods.
2010, 21(6): 696-698
doi: 10.1016/j.cclet.2010.01.041
Abstract:
A new homoflavonoid was isolated from the seed of Caesalpinia minax Hance. On the basis of spectral evidences, its structure was established and named as minaxin.
A new homoflavonoid was isolated from the seed of Caesalpinia minax Hance. On the basis of spectral evidences, its structure was established and named as minaxin.
2010, 21(6): 699-701
doi: 10.1016/j.cclet.2010.01.006
Abstract:
One new dammarane-type triterpene saponin, named (20S)-3β,20,21-trihydroxydammar-24-ene 3-O-[α-L-rhamnopyranosyl-(1→2)] [β-D-xylopyranosyl (l→3)]-β-D-glucopyranoside (1), was isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino. Its structural elucidation was accomplished mainly on the basis of the interrelation of spectroscopic methods, such as IR, HR-TOF-MS, NMR.
One new dammarane-type triterpene saponin, named (20S)-3β,20,21-trihydroxydammar-24-ene 3-O-[α-L-rhamnopyranosyl-(1→2)] [β-D-xylopyranosyl (l→3)]-β-D-glucopyranoside (1), was isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino. Its structural elucidation was accomplished mainly on the basis of the interrelation of spectroscopic methods, such as IR, HR-TOF-MS, NMR.
2010, 21(6): 702-705
doi: 10.1016/j.cclet.2010.01.011
Abstract:
Three new compounds named (2E)prenyl benzoate-4-O-α-L-arabinopyranosyl (1→6) β-D-glucopyranoside (1), 7-methoxy-8-O-β-D-glucopyranosyl coumarin (2), and 3,4'-dihydroxy-3'-methoxy benzenepentanoic acid (3) were isolated from the leaves of Acanthopanax senticosus Harms. The structures of new compounds were determined by means of 2D NMR experiments and chemical methods.
Three new compounds named (2E)prenyl benzoate-4-O-α-L-arabinopyranosyl (1→6) β-D-glucopyranoside (1), 7-methoxy-8-O-β-D-glucopyranosyl coumarin (2), and 3,4'-dihydroxy-3'-methoxy benzenepentanoic acid (3) were isolated from the leaves of Acanthopanax senticosus Harms. The structures of new compounds were determined by means of 2D NMR experiments and chemical methods.
2010, 21(6): 706-708
doi: 10.1016/j.cclet.2010.01.040
Abstract:
Two new homoisoflavanones were isolated from the rhizomes of Polygonatum odoratum (Mill.) Druce and their structures were elucidated as (3R)-5,7-dihydroxy-8-methoxy-3-(4-methoxybenzyl)-6-methylchrom-an-4-one (1) and (3R)-5,7,8-trihydroxy-3-(4-hydroxybenzyl)-6-methylchroman-4-one (2), on the basis of spectral analysis.
Two new homoisoflavanones were isolated from the rhizomes of Polygonatum odoratum (Mill.) Druce and their structures were elucidated as (3R)-5,7-dihydroxy-8-methoxy-3-(4-methoxybenzyl)-6-methylchrom-an-4-one (1) and (3R)-5,7,8-trihydroxy-3-(4-hydroxybenzyl)-6-methylchroman-4-one (2), on the basis of spectral analysis.
2010, 21(6): 709-711
doi: 10.1016/j.cclet.2010.02.007
Abstract:
A new iridoid glucoside, allamanoid (1), was isolated from the aerial parts of Allamanda neriifolia, together with three known glucosides, plumieride, protoplumericin, and nicotiflorin. Their structures were elucidated by 1D and 2D spectroscopic analyses, hydrolysis, and comparison with literature data.
A new iridoid glucoside, allamanoid (1), was isolated from the aerial parts of Allamanda neriifolia, together with three known glucosides, plumieride, protoplumericin, and nicotiflorin. Their structures were elucidated by 1D and 2D spectroscopic analyses, hydrolysis, and comparison with literature data.
2010, 21(6): 712-715
doi: 10.1016/j.cclet.2009.11.013
Abstract:
A simple and sensitive flow injection spectrophotometric method is reported for the determination of vitamin E using potassium ferricyanide-Fe (Ⅲ) detection system. In the presence of vitamin E, Fe (Ⅲ/ferricyanide reduces. The in situ reduced ions are then reacted with unreduced portion of ferricyanide/Fe (Ⅲ to make soluble Prussian blue, which is monitored at absorption wavelength of 735 nm. Linear calibration graph was obtained in the concentration range of 0.1-40 μg mL-1. The relative standard deviations (n=4) were in the range of 1.1-3.6%, with limits of detection (3 s blank) of 0.04 μg mL-1. The proposed method allowed 12 injections h-1. The method is applied to determine vitamin E in Pharmaceuticals, infant milk and blood serum samples using hexane extraction with the recoveries in the range of 93 ±3 to 97.5 ±4%. The method is validated using certified reference materials SRM 968c for blood serum samples.
A simple and sensitive flow injection spectrophotometric method is reported for the determination of vitamin E using potassium ferricyanide-Fe (Ⅲ) detection system. In the presence of vitamin E, Fe (Ⅲ/ferricyanide reduces. The in situ reduced ions are then reacted with unreduced portion of ferricyanide/Fe (Ⅲ to make soluble Prussian blue, which is monitored at absorption wavelength of 735 nm. Linear calibration graph was obtained in the concentration range of 0.1-40 μg mL-1. The relative standard deviations (n=4) were in the range of 1.1-3.6%, with limits of detection (3 s blank) of 0.04 μg mL-1. The proposed method allowed 12 injections h-1. The method is applied to determine vitamin E in Pharmaceuticals, infant milk and blood serum samples using hexane extraction with the recoveries in the range of 93 ±3 to 97.5 ±4%. The method is validated using certified reference materials SRM 968c for blood serum samples.
2010, 21(6): 716-719
doi: 10.1016/j.cclet.2009.12.025
Abstract:
An electrochemical sensor for the detection of the natural double-stranded DNA (dsDNA) damage induced by PbSe quantum dots (QDs) under UV irradiation was developed. The biosensing membranes were prepared by successively assembling 3-mercaptopropionic acid, polycationic poly (diallyldimethyl ammonium) and dsDNA on the surface of the gold electrode. Damage of dsDNA was fulfilled by immersing the sensing membrane electrode in PbSe QDs suspension and illuminating it with an UV lamp. Cyclic voltammetry was utilized to detect dsDNA damage with Co(phen)33+ as the electroactive probe. The UV irradiation, Pb2+ ions liberated from the PbSe QDs under the UV irradiation and the reactive oxygen species (ROS) generated in the presence of the PbSe QDs also under the UV irradiation were the three factors of inducing the dsDNA damage. The synergistic effect of the three factors might dramatically enhance the damage of dsDNA. This electrochemical sensor provided a simple method for detecting DNA damage, and may be used for investigating the DNA damage induced by other QDs.
An electrochemical sensor for the detection of the natural double-stranded DNA (dsDNA) damage induced by PbSe quantum dots (QDs) under UV irradiation was developed. The biosensing membranes were prepared by successively assembling 3-mercaptopropionic acid, polycationic poly (diallyldimethyl ammonium) and dsDNA on the surface of the gold electrode. Damage of dsDNA was fulfilled by immersing the sensing membrane electrode in PbSe QDs suspension and illuminating it with an UV lamp. Cyclic voltammetry was utilized to detect dsDNA damage with Co(phen)33+ as the electroactive probe. The UV irradiation, Pb2+ ions liberated from the PbSe QDs under the UV irradiation and the reactive oxygen species (ROS) generated in the presence of the PbSe QDs also under the UV irradiation were the three factors of inducing the dsDNA damage. The synergistic effect of the three factors might dramatically enhance the damage of dsDNA. This electrochemical sensor provided a simple method for detecting DNA damage, and may be used for investigating the DNA damage induced by other QDs.
2010, 21(6): 720-724
doi: 10.1016/j.cclet.2009.12.028
Abstract:
The interactions of p-dimethylaminobenzaldehyde (p-DAB) and potassium hydrogen sulphate (PHS) in equimolar ratio with various concentration of diphenylamine (solid test material) have been investigated by capillary spot-tests technique in order to investigate the effect of temperature and volume of material in test-tube. The formation of the colored boundary in the capillary is taken for the detection of organic compounds by spot-tests at different temperature and volume of solid test material.
The interactions of p-dimethylaminobenzaldehyde (p-DAB) and potassium hydrogen sulphate (PHS) in equimolar ratio with various concentration of diphenylamine (solid test material) have been investigated by capillary spot-tests technique in order to investigate the effect of temperature and volume of material in test-tube. The formation of the colored boundary in the capillary is taken for the detection of organic compounds by spot-tests at different temperature and volume of solid test material.
2010, 21(6): 725-729
doi: 10.1016/j.cclet.2010.01.015
Abstract:
The acidity constants of TAR in different water-organic solvent binary mixtures at 25℃ have been determined spectro-photometrically. DATa Analysis (DATAN) program was used for calculations of the acidity constants and pure spectra of all formed species and their concentration distribution diagram in applied pH interval. Results show that there are a fairly inverse relationship between acidity constants and the mole fraction of the organic solvent in the binary mixtures. Effects of solvent composition on the pKas and pure spectrum of each component are also discussed.
The acidity constants of TAR in different water-organic solvent binary mixtures at 25℃ have been determined spectro-photometrically. DATa Analysis (DATAN) program was used for calculations of the acidity constants and pure spectra of all formed species and their concentration distribution diagram in applied pH interval. Results show that there are a fairly inverse relationship between acidity constants and the mole fraction of the organic solvent in the binary mixtures. Effects of solvent composition on the pKas and pure spectrum of each component are also discussed.
2010, 21(6): 730-733
doi: 10.1016/j.cclet.2009.12.024
Abstract:
Triacontyl modified silica gel as a sorbent coupled with gas chromatography-mass spectrometry (GC-MS) was developed to determine EPA prior 16 polycyclic aromatic hydrocarbons (PAHs) in water samples. Various parameters of solid-phase extraction such as organic modifier solvent, eluent, sample flow rate and volume were optimized. The developed method was found to yield a linear calibration curve in the concentration range of 0.05-8 μg/L with respect to naphthalene, acenaphthylene, acenaphthene and 0.01-8μg/L for dibenz [a,h]anthracene and 0.05-14 μg/L for fluorene, phenanthrene, anthracene and 0.01-14 μg/L for the rest of analytes. Furthermore, the good accuracy and repeatability of the method made sure the requirements for achieving reliable analysis of PAHs in the environmental water samples, and the recoveries of optimal method were in the range of 80-120% except to higher volatility PAHs. C30-bonded silica was proved to be an efficient sorbent for extraction of high molecular weight PAHs.
Triacontyl modified silica gel as a sorbent coupled with gas chromatography-mass spectrometry (GC-MS) was developed to determine EPA prior 16 polycyclic aromatic hydrocarbons (PAHs) in water samples. Various parameters of solid-phase extraction such as organic modifier solvent, eluent, sample flow rate and volume were optimized. The developed method was found to yield a linear calibration curve in the concentration range of 0.05-8 μg/L with respect to naphthalene, acenaphthylene, acenaphthene and 0.01-8μg/L for dibenz [a,h]anthracene and 0.05-14 μg/L for fluorene, phenanthrene, anthracene and 0.01-14 μg/L for the rest of analytes. Furthermore, the good accuracy and repeatability of the method made sure the requirements for achieving reliable analysis of PAHs in the environmental water samples, and the recoveries of optimal method were in the range of 80-120% except to higher volatility PAHs. C30-bonded silica was proved to be an efficient sorbent for extraction of high molecular weight PAHs.
2010, 21(6): 734-737
doi: 10.1016/j.cclet.2010.01.026
Abstract:
The phase transition of Silwet L-77 (a kind of siloxane surfactant) dilute aqueous solution with temperature was investigated by dielectric relaxation spectroscopy. In the initial heating process, a dielectric relaxation was found at about 106 Hz, which was considered as the interface polarization ascribed to the interface between water and liquid phases (W and L1). With the temperature increasing further, a new dielectric relaxation was observed at about 104 Hz, which was assigned to the appearance of liquid crystal phase (Lα). According to the dielectric parameters fitted by Cole-Cole equation, the coexistence temperature of W, L1 and Lα was determined at about 37.0℃.
The phase transition of Silwet L-77 (a kind of siloxane surfactant) dilute aqueous solution with temperature was investigated by dielectric relaxation spectroscopy. In the initial heating process, a dielectric relaxation was found at about 106 Hz, which was considered as the interface polarization ascribed to the interface between water and liquid phases (W and L1). With the temperature increasing further, a new dielectric relaxation was observed at about 104 Hz, which was assigned to the appearance of liquid crystal phase (Lα). According to the dielectric parameters fitted by Cole-Cole equation, the coexistence temperature of W, L1 and Lα was determined at about 37.0℃.
2010, 21(6): 738-742
doi: 10.1016/j.cclet.2009.12.013
Abstract:
Poly [(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)] was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorotetramethyldisiloxane and dichloromethylsilane. The copolymer was characterized by FT-IR, 1H NMR, differential scanning calorimetry and thermogravi-metric analysis. The results show that the copolymer exhibits good processability and cures at low temperatures. The cured copolymer shows high thermal stability.
Poly [(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)] was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorotetramethyldisiloxane and dichloromethylsilane. The copolymer was characterized by FT-IR, 1H NMR, differential scanning calorimetry and thermogravi-metric analysis. The results show that the copolymer exhibits good processability and cures at low temperatures. The cured copolymer shows high thermal stability.
2010, 21(6): 743-747
doi: 10.1016/j.cclet.2009.12.022
Abstract:
A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile (APN) and 4,4'-bis (3,4-dicyanophenoxy)biphenyl (BPH) by directly powder-mixing and copolymerization. Differential scanning calorimeter (DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends, and the results indicated that the introduction of APN accelerated the curing rate of BPH, and the existence of BPH decreased the curing temperature of APN/BPH systems. The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis (TGA), and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.
A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile (APN) and 4,4'-bis (3,4-dicyanophenoxy)biphenyl (BPH) by directly powder-mixing and copolymerization. Differential scanning calorimeter (DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends, and the results indicated that the introduction of APN accelerated the curing rate of BPH, and the existence of BPH decreased the curing temperature of APN/BPH systems. The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis (TGA), and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.
2010, 21(6): 748-752
doi: 10.1016/j.cclet.2010.02.026
Abstract:
A novel polyester containing ferrocenyl was prepared by low-temperature interface polycondensation of 1,1'-ferrocenedi-carboxylic acid chloride with 4-(4-hydroxyphenyl)-2,3-phthalazin-l-one (DHPZ), which is a twisted non-coplanar heterocyclic bisphenol-like monomer. The newly generated polymer was evaluated based on characterization of its solubility, viscosity measurements, elemental analysis, FTIR spectroscopy, differential scanning calorimetric and thermogravimetric studies.
A novel polyester containing ferrocenyl was prepared by low-temperature interface polycondensation of 1,1'-ferrocenedi-carboxylic acid chloride with 4-(4-hydroxyphenyl)-2,3-phthalazin-l-one (DHPZ), which is a twisted non-coplanar heterocyclic bisphenol-like monomer. The newly generated polymer was evaluated based on characterization of its solubility, viscosity measurements, elemental analysis, FTIR spectroscopy, differential scanning calorimetric and thermogravimetric studies.
2010, 21(6): 753-757
doi: 10.1016/j.cclet.2009.12.027
Abstract:
A novel polyhedral oligomeric silsesquioxane (POSS)-based organic-inorganic hybrid nanocomposite (EF-POSS) was prepared by Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T8H8, POSS) with a luminescent substituted acetylene (2-ethynyl-7-(4-(4-methylstyryl) styryl)-9,9-dioctyl-9H-fluorene (EF)) in high yield. The hybrid nanocomposite was soluble in common solvents such as CH2Cl2, CHCl3, THF and 1,4-dioxane. Its structure and property were characterized by FTIR, NMR, TGA, UV and PL, respectively. The results show that the hybrid nanocomposite with high thermal stability emits stable blue light as a result of photo excitation and possesses high photoluminescence quantum efficiency (φFL).
A novel polyhedral oligomeric silsesquioxane (POSS)-based organic-inorganic hybrid nanocomposite (EF-POSS) was prepared by Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T8H8, POSS) with a luminescent substituted acetylene (2-ethynyl-7-(4-(4-methylstyryl) styryl)-9,9-dioctyl-9H-fluorene (EF)) in high yield. The hybrid nanocomposite was soluble in common solvents such as CH2Cl2, CHCl3, THF and 1,4-dioxane. Its structure and property were characterized by FTIR, NMR, TGA, UV and PL, respectively. The results show that the hybrid nanocomposite with high thermal stability emits stable blue light as a result of photo excitation and possesses high photoluminescence quantum efficiency (φFL).
