Login In
2007 Volume 18 Issue 7
2007, 18(7): 769-772
doi: 10.1016/j.cclet.2007.05.007
Abstract:
Using orthogonal protection-deprotection glycosylation strategy, a series of diosgenyl glycosides with same of monosaccharides component but different in sequence were synthesized. The antitumor activity in vitro of synthesized diosgenyl glycosides was evaluated by standard MTT assay. It was observed that diosgenyl glycosides with a rhamnopyranosyl at C'2 of glucopyranosyl residue show potent antitumor activity in vitro.
Using orthogonal protection-deprotection glycosylation strategy, a series of diosgenyl glycosides with same of monosaccharides component but different in sequence were synthesized. The antitumor activity in vitro of synthesized diosgenyl glycosides was evaluated by standard MTT assay. It was observed that diosgenyl glycosides with a rhamnopyranosyl at C'2 of glucopyranosyl residue show potent antitumor activity in vitro.
2007, 18(7): 773-776
doi: 10.1016/j.cclet.2007.05.021
Abstract:
(E)-α-Iodovinyl sulfones 1 underwent the Sonogashira coupling reactions with terminal alkynes 2 in piperidine at room temperature in the presence of 5 mol% of Pd(PPh3)4 and 10 mol% of CuI to stereospecifically afford the corresponding (Z)-2-sulfonyl-substituted 1, 3-enynes 3 in high yields.
(E)-α-Iodovinyl sulfones 1 underwent the Sonogashira coupling reactions with terminal alkynes 2 in piperidine at room temperature in the presence of 5 mol% of Pd(PPh3)4 and 10 mol% of CuI to stereospecifically afford the corresponding (Z)-2-sulfonyl-substituted 1, 3-enynes 3 in high yields.
2007, 18(7): 777-778
doi: 10.1016/j.cclet.2007.05.020
Abstract:
A novel one-pot synthetic method of 4-methylimidazol-2-one is described. The target compound is conveniently synthesized from sodium diformylamide, a modified Gabriel reagent prepared, through condensation, hydrolyzation and cyclization reactions without separating intermediates, its total yield is 75.8%.
A novel one-pot synthetic method of 4-methylimidazol-2-one is described. The target compound is conveniently synthesized from sodium diformylamide, a modified Gabriel reagent prepared, through condensation, hydrolyzation and cyclization reactions without separating intermediates, its total yield is 75.8%.
2007, 18(7): 779-782
doi: 10.1016/j.cclet.2007.05.037
Abstract:
A highly ordered m-phenylenediimino-bridged ladder polyhydrosiloxane (abbr. OLPHS) with Mn=1.24×104 was synthesized stoichiometric hydrolysis and dehydrochlorination condensation reaction between Si-Cl and Si-OH bonds. The complete ladder structure of OLPHS has been confirmed by the following three data. Two characteristic Bragg's peaks representing the ladder width (w=0.94 nm) and ladder thickness (t=0.42 nm) were observed in XRD analysis, which are consistent with those calculated by molecular simulation. The very sharp absorption with a small half-peak width (w1/2=0.5 ppm) for [(-HN)HSiO2/2]n moiety of OLPHS in 29Si NMR spectrum indicated presence of the complete ladder structure. As collateral evidence, a higher glass transition temperature (Tg=105℃) is also recorded in the DSC measurement, implying the high stiffness of ladder chain of OLPHS.
A highly ordered m-phenylenediimino-bridged ladder polyhydrosiloxane (abbr. OLPHS) with Mn=1.24×104 was synthesized stoichiometric hydrolysis and dehydrochlorination condensation reaction between Si-Cl and Si-OH bonds. The complete ladder structure of OLPHS has been confirmed by the following three data. Two characteristic Bragg's peaks representing the ladder width (w=0.94 nm) and ladder thickness (t=0.42 nm) were observed in XRD analysis, which are consistent with those calculated by molecular simulation. The very sharp absorption with a small half-peak width (w1/2=0.5 ppm) for [(-HN)HSiO2/2]n moiety of OLPHS in 29Si NMR spectrum indicated presence of the complete ladder structure. As collateral evidence, a higher glass transition temperature (Tg=105℃) is also recorded in the DSC measurement, implying the high stiffness of ladder chain of OLPHS.
2007, 18(7): 783-784
doi: 10.1016/j.cclet.2007.05.035
Abstract:
A convenient approach for the preparation of (4R, 5R)-4, 5-bis(aminomethyl)-2-isopropyl-l, 3-dioxolane is described. The target compound via two steps is synthesized from diethyl-2, 3-O-isobutylidene-D-tartrate, through ammonolysis and reduction.
A convenient approach for the preparation of (4R, 5R)-4, 5-bis(aminomethyl)-2-isopropyl-l, 3-dioxolane is described. The target compound via two steps is synthesized from diethyl-2, 3-O-isobutylidene-D-tartrate, through ammonolysis and reduction.
2007, 18(7): 785-787
doi: 10.1016/j.cclet.2007.05.005
Abstract:
A convenient synthetic pathway to 2-aryl-5, 6-dihydro-4H-benzo[f] [1, 2, 4]triazolo[1, 5-a]azepine derivatives 7 was developed.The synthesis was based on the cycloaddition of the 1, 2, 3, 4-tetrahydronaphthalene α-acetoxy azo compounds 3 with Ar-CN in the presence of AlCl3 and the consecutive ring enlargement.
A convenient synthetic pathway to 2-aryl-5, 6-dihydro-4H-benzo[f] [1, 2, 4]triazolo[1, 5-a]azepine derivatives 7 was developed.The synthesis was based on the cycloaddition of the 1, 2, 3, 4-tetrahydronaphthalene α-acetoxy azo compounds 3 with Ar-CN in the presence of AlCl3 and the consecutive ring enlargement.
2007, 18(7): 788-790
doi: 10.1016/j.cclet.2007.05.006
Abstract:
3, 5-Disubstituted 2-isoxazolines were oxidized to corresponding isoxazoles by nitric oxide in dichloromethane. The reaction more likely occurred via a one-electron transfer process.
3, 5-Disubstituted 2-isoxazolines were oxidized to corresponding isoxazoles by nitric oxide in dichloromethane. The reaction more likely occurred via a one-electron transfer process.
2007, 18(7): 791-794
doi: 10.1016/j.cclet.2007.05.030
Abstract:
A series of new diethers were obtained by alkylation of furoin under microwave irradiation (MWI) in phase transfer catalysis (PTC) conditions. The products of alkyl halides were synthesized in good yields (>75%) within a few minutes, and the products of dihalides were synthesized in fair yields (about 45%). The yields are dramatically improved compared to conventional heating under the same conditions, in spite of similar profiles of rising in temperature.
A series of new diethers were obtained by alkylation of furoin under microwave irradiation (MWI) in phase transfer catalysis (PTC) conditions. The products of alkyl halides were synthesized in good yields (>75%) within a few minutes, and the products of dihalides were synthesized in fair yields (about 45%). The yields are dramatically improved compared to conventional heating under the same conditions, in spite of similar profiles of rising in temperature.
2007, 18(7): 795-798
doi: 10.1016/j.cclet.2007.05.012
Abstract:
The photo-promoted carbonylation of chloroalkanes with carbon monoxide was carried out under ambient conditions with copper and cadmium salts catalysts. The results indicated that the corresponding esters were produced with three salt catalysts, i.e. CuBr2, CuCl2 and CdI2. Among these catalysts, CdI2 was the most efficient in terms of ester yield and selectivity, particularly, 60% yield and 75% selectivity in the carbonylation of chlorocyclohexane were achieved. Furthermore, the yield and selectivity of the ester can be improved greatly by adding tri-n-butylamine in the CuBr2 and CuCl2 catalyst systems. On the other hand, the additive. As a result, we suggest that iodide ion plays an important role in the catalyst system of the cadmium salts.
The photo-promoted carbonylation of chloroalkanes with carbon monoxide was carried out under ambient conditions with copper and cadmium salts catalysts. The results indicated that the corresponding esters were produced with three salt catalysts, i.e. CuBr2, CuCl2 and CdI2. Among these catalysts, CdI2 was the most efficient in terms of ester yield and selectivity, particularly, 60% yield and 75% selectivity in the carbonylation of chlorocyclohexane were achieved. Furthermore, the yield and selectivity of the ester can be improved greatly by adding tri-n-butylamine in the CuBr2 and CuCl2 catalyst systems. On the other hand, the additive. As a result, we suggest that iodide ion plays an important role in the catalyst system of the cadmium salts.
2007, 18(7): 799-802
doi: 10.1016/j.cclet.2007.05.001
Abstract:
A synergistic catalytic effect between copper methanesulfonate and acetic acid in tetrahydropyranylation of alcohols and phenol at room temperature under solvent free condition has been described. Both alcohols (primary, secondary and tertiary) and phenols reacted with 3, 4-dihydro-2H-pyran smoothly to afford the corresponding tetrahydropyranyl ethers in good yields.
A synergistic catalytic effect between copper methanesulfonate and acetic acid in tetrahydropyranylation of alcohols and phenol at room temperature under solvent free condition has been described. Both alcohols (primary, secondary and tertiary) and phenols reacted with 3, 4-dihydro-2H-pyran smoothly to afford the corresponding tetrahydropyranyl ethers in good yields.
2007, 18(7): 803-806
doi: 10.1016/j.cclet.2007.05.050
Abstract:
Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe(HSO4)3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.
Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe(HSO4)3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.
2007, 18(7): 807-810
doi: 10.1016/j.cclet.2007.05.036
Abstract:
N, N-Dimethylaniline hydroperoxide was obtained when treating N, N-dimethylaniline with NHPI/Co(OAc)2/O2 via a radical reaction mechanism. This intermediate has potential application in the synthesis of some important chemical scaffolds.
N, N-Dimethylaniline hydroperoxide was obtained when treating N, N-dimethylaniline with NHPI/Co(OAc)2/O2 via a radical reaction mechanism. This intermediate has potential application in the synthesis of some important chemical scaffolds.
2007, 18(7): 811-813
doi: 10.1016/j.cclet.2007.05.004
Abstract:
The condensation reaction of formaldehyde and methyl formate to form methyl glycolate and methyl methoxy acetate catalyzed by p-toluenesulfonic acid and different Lewis acid compounds has been investigated. The composite catalytic system consisting of p-toluenesulfonic acid and NiX2(X=Cl, Br, I), especially NiI2, exhibited a high catalytic performance for the condensation reaction, the total yield of MG and MMAc was up to 72.37%.
The condensation reaction of formaldehyde and methyl formate to form methyl glycolate and methyl methoxy acetate catalyzed by p-toluenesulfonic acid and different Lewis acid compounds has been investigated. The composite catalytic system consisting of p-toluenesulfonic acid and NiX2(X=Cl, Br, I), especially NiI2, exhibited a high catalytic performance for the condensation reaction, the total yield of MG and MMAc was up to 72.37%.
2007, 18(7): 814-816
doi: 10.1016/j.cclet.2007.05.024
Abstract:
A series of phenylbenzamidine analogs were synthesized and tested for their biological activities of inhibiting the reuptake of 5-HT. All of them were new compounds, and their structures were confirmed by 1HNMR, MS and XRD.
A series of phenylbenzamidine analogs were synthesized and tested for their biological activities of inhibiting the reuptake of 5-HT. All of them were new compounds, and their structures were confirmed by 1HNMR, MS and XRD.
2007, 18(7): 817-819
doi: 10.1016/j.cclet.2007.05.013
Abstract:
A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG22.2.15 cells. Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with EC50 and CC50 values of 0.207 μmol/L and 2530 μmol/L, respectively.
A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG22.2.15 cells. Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with EC50 and CC50 values of 0.207 μmol/L and 2530 μmol/L, respectively.
2007, 18(7): 820-822
doi: 10.1016/j.cclet.2007.04.039
Abstract:
A donor-bridge-donor compound for blue light-emitting with triphenylamine as donor and pentiptycene derivative units as bridge was synthesized via Sonogashira reaction. The chemical structure was confirmed by NMR and MALDI-TOF MS. It emits blue light peaked at 442 nm with a FWHM of 59 nm in CH2Cl2. Fluorescent quantum efficiency in THF is 82% relative to 9, 10-diphenylanthracene. A slight hypsochromic shift was found in its drop-cast film. Cyclic voltammetry revealed that it has high HOMO level corresponding to hole transporting character.
A donor-bridge-donor compound for blue light-emitting with triphenylamine as donor and pentiptycene derivative units as bridge was synthesized via Sonogashira reaction. The chemical structure was confirmed by NMR and MALDI-TOF MS. It emits blue light peaked at 442 nm with a FWHM of 59 nm in CH2Cl2. Fluorescent quantum efficiency in THF is 82% relative to 9, 10-diphenylanthracene. A slight hypsochromic shift was found in its drop-cast film. Cyclic voltammetry revealed that it has high HOMO level corresponding to hole transporting character.
2007, 18(7): 823-826
doi: 10.1016/j.cclet.2007.05.016
Abstract:
An excellent organic blue light-emitting diode based on 4, 4'-bis(diphenylamino)-quinque(p-phenylene)s (OPP(5)-NPh) with a maximum luminance of up to 5000 cd/m2 and a luminanous efficiency of 1.3 cd/A was reported. This diode was made by using a wide band-gap hole-blocking layer, F-TBB instead of PBD in the OLED devices. We attribute the good performance to the one trade-off involved in the use of F-TBB to obtain higher luminance is the increased turn-on voltages and slightly decreased device efficiencies.
An excellent organic blue light-emitting diode based on 4, 4'-bis(diphenylamino)-quinque(p-phenylene)s (OPP(5)-NPh) with a maximum luminance of up to 5000 cd/m2 and a luminanous efficiency of 1.3 cd/A was reported. This diode was made by using a wide band-gap hole-blocking layer, F-TBB instead of PBD in the OLED devices. We attribute the good performance to the one trade-off involved in the use of F-TBB to obtain higher luminance is the increased turn-on voltages and slightly decreased device efficiencies.
2007, 18(7): 827-830
doi: 10.1016/j.cclet.2007.05.019
Abstract:
Stannous-acetylacetonate was prepared efficiently and characterized by 1H NMR and FT-IR. Its catalytic activity for poly(trimethylene terephthalate) (PTT) synthesis was investigated. By this catalyst, the degree of esterification of pure terephthalic acid was up to 91.7% after reaction at 260℃ for 2 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polymerized at 260℃, 60 Pa for 2 h was 0.8816 dL/g and 17 mol/t, respectively. Stannous-acetylacetonate was more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.
Stannous-acetylacetonate was prepared efficiently and characterized by 1H NMR and FT-IR. Its catalytic activity for poly(trimethylene terephthalate) (PTT) synthesis was investigated. By this catalyst, the degree of esterification of pure terephthalic acid was up to 91.7% after reaction at 260℃ for 2 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polymerized at 260℃, 60 Pa for 2 h was 0.8816 dL/g and 17 mol/t, respectively. Stannous-acetylacetonate was more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.
2007, 18(7): 831-834
doi: 10.1016/j.cclet.2007.05.014
Abstract:
From the stems of Marsdenia tenacissima two new polyoxypregnanes were isolated, their structures were elucidated by 1D, 2D-NMR as 11α, 12β-di-O-tigloyl-tenacigenin B (1) and tenacigenoside E (2).
From the stems of Marsdenia tenacissima two new polyoxypregnanes were isolated, their structures were elucidated by 1D, 2D-NMR as 11α, 12β-di-O-tigloyl-tenacigenin B (1) and tenacigenoside E (2).
2007, 18(7): 835-836
doi: 10.1016/j.cclet.2007.04.035
Abstract:
A new coumarin glycoside was isolated from the ethanol extract of the barks of stem of Daphne giraldii Nitsche. Its structure was defined as daphnetin 8-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside on the basis of spectral evidences.
A new coumarin glycoside was isolated from the ethanol extract of the barks of stem of Daphne giraldii Nitsche. Its structure was defined as daphnetin 8-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside on the basis of spectral evidences.
2007, 18(7): 837-839
doi: 10.1016/j.cclet.2007.05.018
Abstract:
Two new acetylated flavonoid diglycosides, scutellarein-5-O-[α-L-rhamnopyranosyl-(1→4)-β-D-6-O-acetylglucopyranoside](1), apigenin-5-O-[α-L-rhamnopyranosyl-(1→2)-β-D-3, 6-di-O-acetylglucopyranoside] (2), were isolated from the leaves of Cephalotaxus sinensis. Their structures were determined by chemical and spectroscopic methods including HR-FAB-MS, 1H-1H COSY, HSQC and HMBC experiments.
Two new acetylated flavonoid diglycosides, scutellarein-5-O-[α-L-rhamnopyranosyl-(1→4)-β-D-6-O-acetylglucopyranoside](1), apigenin-5-O-[α-L-rhamnopyranosyl-(1→2)-β-D-3, 6-di-O-acetylglucopyranoside] (2), were isolated from the leaves of Cephalotaxus sinensis. Their structures were determined by chemical and spectroscopic methods including HR-FAB-MS, 1H-1H COSY, HSQC and HMBC experiments.
2007, 18(7): 840-842
doi: 10.1016/j.cclet.2007.05.033
Abstract:
A novel chalcone derivative was isolated from Onychium japonicum and its structure was elucidated by spectroscopic methods.The isolated compound showed cytotoxic activity against the human carcinoma cell lines Hela and BEL-7402 in vitro.
A novel chalcone derivative was isolated from Onychium japonicum and its structure was elucidated by spectroscopic methods.The isolated compound showed cytotoxic activity against the human carcinoma cell lines Hela and BEL-7402 in vitro.
2007, 18(7): 843-845
doi: 10.1016/j.cclet.2007.05.022
Abstract:
One new cucurbitane-type triterpenoid saponin, 5β, 19-epoxycucurbita-6, 23-diene-3β, 19, 25-triol-3-O-β-D-allopyranoside (1), named momordicoside P was isolated from the fresh fruits of Momordica charantia. The structure of the saponin was elucidated by spectral methods, including 2D-NMR spectra.
One new cucurbitane-type triterpenoid saponin, 5β, 19-epoxycucurbita-6, 23-diene-3β, 19, 25-triol-3-O-β-D-allopyranoside (1), named momordicoside P was isolated from the fresh fruits of Momordica charantia. The structure of the saponin was elucidated by spectral methods, including 2D-NMR spectra.
2007, 18(7): 846-848
doi: 10.1016/j.cclet.2007.05.043
Abstract:
From Juglans mandshurica leaves, a new quinone compound was isolated through bioassay-guided fractionation. The structure elucidation of the compound was established based on spectroscopic studies, notably of the 2D NMR spectra. The compound exhibited moderate cytotoxic activities against Hela, MCF-7, BGC823 and 3T3-Llcell lines with IC50 ranges from 7.5 to 26.8 μmol/L.
From Juglans mandshurica leaves, a new quinone compound was isolated through bioassay-guided fractionation. The structure elucidation of the compound was established based on spectroscopic studies, notably of the 2D NMR spectra. The compound exhibited moderate cytotoxic activities against Hela, MCF-7, BGC823 and 3T3-Llcell lines with IC50 ranges from 7.5 to 26.8 μmol/L.
2007, 18(7): 849-851
doi: 10.1016/j.cclet.2007.05.045
Abstract:
Two novel xanthones, 1, 6-dihydroxy-4, 5-dimethoxyxanthone (1) and 1, 5, 6-trihydroxy-7, 8-di(3-methyl-2-butenyl)-6', 6'-dimethylpyrano(2', 3':3, 4)xanthone (2) were isolated from the bark of Garcinia xanthochymus by normal phase and reverse phase silica gel column chromatography. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques.
Two novel xanthones, 1, 6-dihydroxy-4, 5-dimethoxyxanthone (1) and 1, 5, 6-trihydroxy-7, 8-di(3-methyl-2-butenyl)-6', 6'-dimethylpyrano(2', 3':3, 4)xanthone (2) were isolated from the bark of Garcinia xanthochymus by normal phase and reverse phase silica gel column chromatography. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques.
2007, 18(7): 852-856
doi: 10.1016/j.cclet.2007.05.023
Abstract:
A novel near infrared (NIR) modeling method-Laplacian regularized least squares regression (LapRLSR) was presented, which can take the advantage of many unlabeled spectra to promote the prediction performance of the model even if there are only few calibration samples. Using LapRLSR modeling, NIR spectral analysis was applied to the online monitoring of the concentration of salvia acid B in the column separation of Salvianolate. The results demonstrated that LapRLSR outperformed partial least squares (PLS) significantly, and NIR online analysis was applicable.
A novel near infrared (NIR) modeling method-Laplacian regularized least squares regression (LapRLSR) was presented, which can take the advantage of many unlabeled spectra to promote the prediction performance of the model even if there are only few calibration samples. Using LapRLSR modeling, NIR spectral analysis was applied to the online monitoring of the concentration of salvia acid B in the column separation of Salvianolate. The results demonstrated that LapRLSR outperformed partial least squares (PLS) significantly, and NIR online analysis was applicable.
2007, 18(7): 857-860
doi: 10.1016/j.cclet.2007.05.011
Abstract:
In this paper, differential pulse voltammetry (DPV) was applied to study the effects of aluminum Al(Ⅲ) on the lactate dehydrogenase (LDH) activity. Michaelis-Menten constant (KmNADH) and maximum velocity (υmax) in the enzyme promoting catalytic reaction of "pyruvate(Pyr)+NADH+H+ ??? lactate+NAD+" under different conditions by monitoring DPV reduction current of NAD+ were reported.
In this paper, differential pulse voltammetry (DPV) was applied to study the effects of aluminum Al(Ⅲ) on the lactate dehydrogenase (LDH) activity. Michaelis-Menten constant (KmNADH) and maximum velocity (υmax) in the enzyme promoting catalytic reaction of "pyruvate(Pyr)+NADH+H+ ??? lactate+NAD+" under different conditions by monitoring DPV reduction current of NAD+ were reported.
2007, 18(7): 861-864
doi: 10.1016/j.cclet.2007.05.025
Abstract:
Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues, respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.
Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues, respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.
2007, 18(7): 865-868
doi: 10.1016/j.cclet.2007.05.027
Abstract:
Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorum was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly, from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.
Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorum was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly, from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.
2007, 18(7): 869-871
doi: 10.1016/j.cclet.2007.05.002
Abstract:
A new approach combined the specificity of allele-specific amplification (ASA) with the sensitivity of electrochemiluminescence (ECL) assay for single nucleotide polymorphism (SNP) analysis was proposed. Briefly, target gene was amplified by a biotin-labeled allele-specific forward primer and a Ru(bpy)32+ (TBR)-labeled universal reverse primer. Then, the amplicon was captured onto streptavidin-coated paramagnetic beads through biotin label, and detected by measuring the ECL signal of TBR label. Different genotypes were distinguished according to the ECL values of the amplicons by different genotypic primers. K-ras oncogene was used as a target to validate the feasibility of the method. The experiment results show that the different genotypes can be clearly distinguished by ASA-ECL assay. The method is useful in SNP analysis due to its sensitivity, safety, and simplicity.
A new approach combined the specificity of allele-specific amplification (ASA) with the sensitivity of electrochemiluminescence (ECL) assay for single nucleotide polymorphism (SNP) analysis was proposed. Briefly, target gene was amplified by a biotin-labeled allele-specific forward primer and a Ru(bpy)32+ (TBR)-labeled universal reverse primer. Then, the amplicon was captured onto streptavidin-coated paramagnetic beads through biotin label, and detected by measuring the ECL signal of TBR label. Different genotypes were distinguished according to the ECL values of the amplicons by different genotypic primers. K-ras oncogene was used as a target to validate the feasibility of the method. The experiment results show that the different genotypes can be clearly distinguished by ASA-ECL assay. The method is useful in SNP analysis due to its sensitivity, safety, and simplicity.
2007, 18(7): 872-874
doi: 10.1016/j.cclet.2007.03.012
Abstract:
Stannous oxalate was prepared efficiently and characterized by XRD and FT-IR. It exhibited higher catalytic activity and had profitable effect than tetrabutyl titanate and stannous octoate for the synthesis of polytrimethylene terephthalate (PTT) via esterification-route. Over this catalyst, the degree of esterification of pure terephthalic acid was up to 94.4% at 260℃ after 1.5 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polyester, polymerized at 260℃, 60 Pa for 2 h, was 0.8950 dL/g and 15 mol/t, respectively. Stannous oxalate was a promising catalyst for the synthesis of PTT polyester.
Stannous oxalate was prepared efficiently and characterized by XRD and FT-IR. It exhibited higher catalytic activity and had profitable effect than tetrabutyl titanate and stannous octoate for the synthesis of polytrimethylene terephthalate (PTT) via esterification-route. Over this catalyst, the degree of esterification of pure terephthalic acid was up to 94.4% at 260℃ after 1.5 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polyester, polymerized at 260℃, 60 Pa for 2 h, was 0.8950 dL/g and 15 mol/t, respectively. Stannous oxalate was a promising catalyst for the synthesis of PTT polyester.
2007, 18(7): 875-878
doi: 10.1016/j.cclet.2007.05.010
Abstract:
We report here an approach toward the synthesis of optically active polyacrylamide bearing amino acid moieties, poly[N-methacryloyl L-leucine methyl ester] (PMALM), with controlled average number molecular weight (Mn) and relatively narrow polydispersity index (PDI, Mw/Mn <1.3) by atom transfer radical polymerization (ATRP) using initiating system methyl 2-bromopropionate/CuBr/tris(2-dimethylaminoethyl) amine. The optical properties of the resulting polymers were evaluated from specific optical rotation value and CD spectra.
We report here an approach toward the synthesis of optically active polyacrylamide bearing amino acid moieties, poly[N-methacryloyl L-leucine methyl ester] (PMALM), with controlled average number molecular weight (Mn) and relatively narrow polydispersity index (PDI, Mw/Mn <1.3) by atom transfer radical polymerization (ATRP) using initiating system methyl 2-bromopropionate/CuBr/tris(2-dimethylaminoethyl) amine. The optical properties of the resulting polymers were evaluated from specific optical rotation value and CD spectra.
2007, 18(7): 879-882
doi: 10.1016/j.cclet.2007.05.040
Abstract:
To search for more wider absorption and higher charge carriers mobilities materials of polymer solar cell, a series of soluble alternating polyfluorene copolymers were synthesized by palladium-catalyzed Suzuki coupling reaction. Their structures were determined by 1H NMR, IR and UV-vis. And their UV-vis absorption spectra indicated that they had strong absorption over 600 nm spectral range and nearly cover 400-700 nm visible region. The band gaps of copolymers calculated according to cyclic voltammetry (CV) were between 1.96 and 2.03 eV. Polymer:TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide, a precursor for TiO2, via hydrolysis in air overnight. The photoluminescence at 380-800 nm of the blend film of PT-TPP20(5 mg/mL):Ti(OC3H7)4 (80 μL/mL) (20% volume fraction) was significantly quenched in the 50% Ti(OC3H7)4 blend film, indicating that rapid and efficient separation of photoinduced electron-hole pairs.
To search for more wider absorption and higher charge carriers mobilities materials of polymer solar cell, a series of soluble alternating polyfluorene copolymers were synthesized by palladium-catalyzed Suzuki coupling reaction. Their structures were determined by 1H NMR, IR and UV-vis. And their UV-vis absorption spectra indicated that they had strong absorption over 600 nm spectral range and nearly cover 400-700 nm visible region. The band gaps of copolymers calculated according to cyclic voltammetry (CV) were between 1.96 and 2.03 eV. Polymer:TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide, a precursor for TiO2, via hydrolysis in air overnight. The photoluminescence at 380-800 nm of the blend film of PT-TPP20(5 mg/mL):Ti(OC3H7)4 (80 μL/mL) (20% volume fraction) was significantly quenched in the 50% Ti(OC3H7)4 blend film, indicating that rapid and efficient separation of photoinduced electron-hole pairs.
2007, 18(7): 883-886
doi: 10.1016/j.cclet.2007.05.003
Abstract:
The high quality TiO2, MoO3-doped WO3 electrochromic film was prepared by the sol-gel method for the first time.The sol, which has hydrogen peroxide (H2O2) and oxalic acid (H2C2O4), was very stable at room temperature and quite suitable for the deposition of films. The WO3electrochromic film prepared from this doped sol had excellent performance, such as short response time, no cracks, good adhesion to the substrate, high coloring efficiency and longevity of service.
The high quality TiO2, MoO3-doped WO3 electrochromic film was prepared by the sol-gel method for the first time.The sol, which has hydrogen peroxide (H2O2) and oxalic acid (H2C2O4), was very stable at room temperature and quite suitable for the deposition of films. The WO3electrochromic film prepared from this doped sol had excellent performance, such as short response time, no cracks, good adhesion to the substrate, high coloring efficiency and longevity of service.
2007, 18(7): 887-890
doi: 10.1016/j.cclet.2007.05.017
Abstract:
Various novel double metal cyanide (DMC) catalysts were successfully prepared by modifying the central metal (M) and one of cyanide ion (CN-) in Zna[M(CN)b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni(Ⅱ) DMC is a potential catalyst for alternating copolymerization of PO/CO2, and DMC catalysts based on Zn3[Co(CN)5X]2 (X=Br- and N3-) exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.
Various novel double metal cyanide (DMC) catalysts were successfully prepared by modifying the central metal (M) and one of cyanide ion (CN-) in Zna[M(CN)b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni(Ⅱ) DMC is a potential catalyst for alternating copolymerization of PO/CO2, and DMC catalysts based on Zn3[Co(CN)5X]2 (X=Br- and N3-) exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.
2007, 18(7): 891-894
doi: 10.1016/j.cclet.2007.05.009
Abstract:
The changes of thermodynamic properties of the system on interaction between tegafur and human serum albumin (HSA) and the changes of secondary structure units of HSA in the system at 298.15 K have been investigated by the Nano-Watt-Scale isothermal titration calorimetry (ITC), the Langmuirs binding model and the circular dichroism (CD) spectrometry.
The changes of thermodynamic properties of the system on interaction between tegafur and human serum albumin (HSA) and the changes of secondary structure units of HSA in the system at 298.15 K have been investigated by the Nano-Watt-Scale isothermal titration calorimetry (ITC), the Langmuirs binding model and the circular dichroism (CD) spectrometry.
