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2007 Volume 18 Issue 3
2007, 18(3): 247-250
doi: 10.1016/j.cclet.2006.12.026
Abstract:
To enable insulin as multi-drug carrier, we designed and synthesized dendritic linker molecule bearing three 5-fluorouracil residues at the branch ends. The new conjugate showed excellent water solubility. The stabilities under different conditions were investigated. The results showed that the conjugate was a potential prodrug to release free 5-Fu.
To enable insulin as multi-drug carrier, we designed and synthesized dendritic linker molecule bearing three 5-fluorouracil residues at the branch ends. The new conjugate showed excellent water solubility. The stabilities under different conditions were investigated. The results showed that the conjugate was a potential prodrug to release free 5-Fu.
2007, 18(3): 251-254
doi: 10.1016/j.cclet.2006.12.029
Abstract:
A series of 2-alkylbenzimidazole derivatives 9a-n have been designed and synthesized as a novel class of non-peptide angiotensin Ⅱ AT1 receptor antagonists. The synthesized compounds were evaluated for their antagonism of angiotensin Ⅱ, induced contraction in the rabbit thoracic aortic ring and the results showed that compounds 9a, 9g and 9j exhibited potent antagonistic activity of AT1 receptor.
A series of 2-alkylbenzimidazole derivatives 9a-n have been designed and synthesized as a novel class of non-peptide angiotensin Ⅱ AT1 receptor antagonists. The synthesized compounds were evaluated for their antagonism of angiotensin Ⅱ, induced contraction in the rabbit thoracic aortic ring and the results showed that compounds 9a, 9g and 9j exhibited potent antagonistic activity of AT1 receptor.
2007, 18(3): 255-257
doi: 10.1016/j.cclet.2007.01.035
Abstract:
The asymmetric total synthesis of herbarumin Ⅲ 3, a naturally occurred phytotoxin, along with 8-epi-herbarumin Ⅲ 22, was succeeded in 12 steps from n-butyraldehyde based on Brown's asymmetric allylation, taking modified Julia olefination and Yamaguchi's macro-lactonization as key steps.
The asymmetric total synthesis of herbarumin Ⅲ 3, a naturally occurred phytotoxin, along with 8-epi-herbarumin Ⅲ 22, was succeeded in 12 steps from n-butyraldehyde based on Brown's asymmetric allylation, taking modified Julia olefination and Yamaguchi's macro-lactonization as key steps.
2007, 18(3): 258-260
doi: 10.1016/j.cclet.2007.01.036
Abstract:
The synthesis of cinnamoyl thiourea derivatives from cinnamoyl isothiocyanate (CIT) with substituted aniline (RC6H4NH2) was investigated in the mostly used ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4]. Significant enhancements in reactivity, yield and reaction rate were achieved. The products could be recovered by simple filtration. [Bmim][BF4] could be recycled simply by removing water under vacuum and reused at least 9 times without significant decrease in activity.
The synthesis of cinnamoyl thiourea derivatives from cinnamoyl isothiocyanate (CIT) with substituted aniline (RC6H4NH2) was investigated in the mostly used ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4]. Significant enhancements in reactivity, yield and reaction rate were achieved. The products could be recovered by simple filtration. [Bmim][BF4] could be recycled simply by removing water under vacuum and reused at least 9 times without significant decrease in activity.
2007, 18(3): 261-262
doi: 10.1016/j.cclet.2007.01.025
Abstract:
An optically active intermediate 5 for A-ring of 19-nor-1α,25-dihydroxyvitamin D3 2 has been synthesized in five steps, starting from readily available, inexpensive D(+)-xylose 6 with good yield.
An optically active intermediate 5 for A-ring of 19-nor-1α,25-dihydroxyvitamin D3 2 has been synthesized in five steps, starting from readily available, inexpensive D(+)-xylose 6 with good yield.
2007, 18(3): 263-265
doi: 10.1016/j.cclet.2007.01.011
Abstract:
p-tert-Butylcalix[4]diazacrown-4 telomer, which contains hard and soft ion binding sites, was synthesized. It exhibited high selectivity toward cesium ions. The binding sites may complex alkali metal ions selectively.
p-tert-Butylcalix[4]diazacrown-4 telomer, which contains hard and soft ion binding sites, was synthesized. It exhibited high selectivity toward cesium ions. The binding sites may complex alkali metal ions selectively.
2007, 18(3): 266-268
doi: 10.1016/j.cclet.2007.01.023
Abstract:
Poly(vinyl chloride) supported tetraethylenepentamine (PVC-TEPA) has been found to be an efficient catalyst for the Knoevenagel condensation. A wide range of aromatic aldehydes easily undergo condensations with ethyl cyanoacetate and malononitrile in the commercial 95% ethanol in refluxing using PVC-TEPA as catalyst to afford the desired products of good purity in moderate to excellent yields. A recycling study confirmed that the catalyst could be reused, the yield of the desired condensation product were not reduced. The merits of this protocol are environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can easily be recovered and reused at five times with comparable yields.
Poly(vinyl chloride) supported tetraethylenepentamine (PVC-TEPA) has been found to be an efficient catalyst for the Knoevenagel condensation. A wide range of aromatic aldehydes easily undergo condensations with ethyl cyanoacetate and malononitrile in the commercial 95% ethanol in refluxing using PVC-TEPA as catalyst to afford the desired products of good purity in moderate to excellent yields. A recycling study confirmed that the catalyst could be reused, the yield of the desired condensation product were not reduced. The merits of this protocol are environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can easily be recovered and reused at five times with comparable yields.
2007, 18(3): 269-271
doi: 10.1016/j.cclet.2007.01.020
Abstract:
The nitrozation reaction of cyclohexane in one-step reaction to form ε-caprolactam has been studied using transition metal salt as catalysts in this work. The results indicated that the catalysts play an especially important role. This method is expected to be a novel way to synthesize other lactam by similar reaction. The possible mechanism was suggested.
The nitrozation reaction of cyclohexane in one-step reaction to form ε-caprolactam has been studied using transition metal salt as catalysts in this work. The results indicated that the catalysts play an especially important role. This method is expected to be a novel way to synthesize other lactam by similar reaction. The possible mechanism was suggested.
2007, 18(3): 272-274
doi: 10.1016/j.cclet.2007.01.027
Abstract:
A fast and convenient base-free Heck reaction of acrylic acid with hypervalent iodonium salts was achieved under microwave irradiation in water, providing a simple method for the synthesis of trans-cinnamic acids in good yields in short time.
A fast and convenient base-free Heck reaction of acrylic acid with hypervalent iodonium salts was achieved under microwave irradiation in water, providing a simple method for the synthesis of trans-cinnamic acids in good yields in short time.
2007, 18(3): 275-278
doi: 10.1016/j.cclet.2007.01.022
Abstract:
Sciff bases 1 and 2, which were derived from chiral aminoalcohols, were used as ligands in Ti-catalyzed asymmetric alkynylation of aldehydes. Good enantioselectivities (up to 88% ee) and high chemical yields (80-90%) were obtained.
Sciff bases 1 and 2, which were derived from chiral aminoalcohols, were used as ligands in Ti-catalyzed asymmetric alkynylation of aldehydes. Good enantioselectivities (up to 88% ee) and high chemical yields (80-90%) were obtained.
2007, 18(3): 279-282
doi: 10.1016/j.cclet.2007.01.028
Abstract:
Ionic liquids (ILs) based on 1,3-dialkylimidazolium and teraalkylammonium cations were employed as a series of efficient,environmentally benign phase-transfer catalysts (PTCs) for the base-promoted monoalkylation of diethyl malonate. The influence of various heterogeneous bases on yields was studied. Good yields and high selectivity were obtained. Solvent-free, mild reaction condition, short reaction time, and easy purification were the merits of this method. The catalytic system (IL-base) could also be recycled after the extraction of products with ether.
Ionic liquids (ILs) based on 1,3-dialkylimidazolium and teraalkylammonium cations were employed as a series of efficient,environmentally benign phase-transfer catalysts (PTCs) for the base-promoted monoalkylation of diethyl malonate. The influence of various heterogeneous bases on yields was studied. Good yields and high selectivity were obtained. Solvent-free, mild reaction condition, short reaction time, and easy purification were the merits of this method. The catalytic system (IL-base) could also be recycled after the extraction of products with ether.
2007, 18(3): 283-286
doi: 10.1016/j.cclet.2007.01.014
Abstract:
Novel perylene bisimide dyes bay-functionalized with naphthalimide chromophores have been prepared conveniently by coupling of 1,8-naphthalimide and dibromoperylene bisimides. Their optical properties were investigated by UV-vis and fluorescence spectroscopy. The absorption spectra of these compounds showed wide spectral responses from 300 to 700 nm,which would be potentials for application as organic solar cells.
Novel perylene bisimide dyes bay-functionalized with naphthalimide chromophores have been prepared conveniently by coupling of 1,8-naphthalimide and dibromoperylene bisimides. Their optical properties were investigated by UV-vis and fluorescence spectroscopy. The absorption spectra of these compounds showed wide spectral responses from 300 to 700 nm,which would be potentials for application as organic solar cells.
2007, 18(3): 287-290
doi: 10.1016/j.cclet.2007.01.038
Abstract:
A novel type of molecular tweezer receptors based on deoxycholic acid has been designed and synthesized and their binding properties were examined by UV-vis spectral titration. These molecular tweezers showed a high selectivity toward F- over Cl-,Br-, I-, AcO-, H2PO4-.
A novel type of molecular tweezer receptors based on deoxycholic acid has been designed and synthesized and their binding properties were examined by UV-vis spectral titration. These molecular tweezers showed a high selectivity toward F- over Cl-,Br-, I-, AcO-, H2PO4-.
2007, 18(3): 291-292
doi: 10.1016/j.cclet.2007.01.003
Abstract:
A new ellagitannin, named bractin (1), had been isolated from the dried aerial part of Cleidion bracteosum. Its structure was determined based on various of spectral analysis.
A new ellagitannin, named bractin (1), had been isolated from the dried aerial part of Cleidion bracteosum. Its structure was determined based on various of spectral analysis.
2007, 18(3): 293-296
doi: 10.1016/j.cclet.2007.01.007
Abstract:
A new prenylated dihydroflavonoid was obtained from the root of Dolichos tenuicaulis (Baker) Craib. The structure was elucidated as (2S)-5,2',6'-trihydroxy-3''', 8-di (γ, γ-dimethyl-allyl)-2''', 2'''-dimethylpyrano-[5''',6''':6,7]-2''''',4'''''-cyclohexadiene-1'''''-one-[2''''',3''''':3',4']-flavanone, named dolichnin A, by spectroscopic methods including UV, IR, HR-EI-MS, 1D NMR and 2D NMR techniques, and subsequently, the anticancer activity of this compound to inhibit human cancer cells' growth including A549, BEL-7402, Hep-3B, SMMC7721, HT-29, MCF-7, SGC-7902, K562, A498 and PC3 cell lines by MTT method was evaluated in vitro.
A new prenylated dihydroflavonoid was obtained from the root of Dolichos tenuicaulis (Baker) Craib. The structure was elucidated as (2S)-5,2',6'-trihydroxy-3''', 8-di (γ, γ-dimethyl-allyl)-2''', 2'''-dimethylpyrano-[5''',6''':6,7]-2''''',4'''''-cyclohexadiene-1'''''-one-[2''''',3''''':3',4']-flavanone, named dolichnin A, by spectroscopic methods including UV, IR, HR-EI-MS, 1D NMR and 2D NMR techniques, and subsequently, the anticancer activity of this compound to inhibit human cancer cells' growth including A549, BEL-7402, Hep-3B, SMMC7721, HT-29, MCF-7, SGC-7902, K562, A498 and PC3 cell lines by MTT method was evaluated in vitro.
2007, 18(3): 297-299
doi: 10.1016/j.cclet.2007.01.008
Abstract:
A new isoflavonolignan has been isolated from the Pueraria alopecuroides Craib. The structure was elucidated by the combination of 1D, 2D NMR analysis and mass spectrometry.
A new isoflavonolignan has been isolated from the Pueraria alopecuroides Craib. The structure was elucidated by the combination of 1D, 2D NMR analysis and mass spectrometry.
2007, 18(3): 300-302
doi: 10.1016/j.cclet.2007.01.013
Abstract:
A new C21 steroidal glycoside, neocynapanogenin F 3-O-β-D-thevetoside 1, as well as its known aglycone neocynapanogerin F 2, which have an aberrant 13, 14:14, 15-disecopregnane-type skeleton were isolated from the root of Cynanchum paniculatum.Their structures were elucidated on the basis of spectroscopic data analysis. These compounds showed certain cytotoxic activities in vitro.
A new C21 steroidal glycoside, neocynapanogenin F 3-O-β-D-thevetoside 1, as well as its known aglycone neocynapanogerin F 2, which have an aberrant 13, 14:14, 15-disecopregnane-type skeleton were isolated from the root of Cynanchum paniculatum.Their structures were elucidated on the basis of spectroscopic data analysis. These compounds showed certain cytotoxic activities in vitro.
2007, 18(3): 303-305
doi: 10.1016/j.cclet.2007.01.029
Abstract:
A new xanthene, named blumeaxanthene, was isolated from Blumea riparia DC. The structure was elucidated on the basis of the data of NMR, MS, IR.
A new xanthene, named blumeaxanthene, was isolated from Blumea riparia DC. The structure was elucidated on the basis of the data of NMR, MS, IR.
2007, 18(3): 306-308
doi: 10.1016/j.cclet.2007.01.009
Abstract:
A new triterpenoid saponin, 3-O-β-D-glucopyranosyl 16-oxo-platycodigenin 28-O-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyra-nosyl ester, was isolated from the roots of Platycodon grandiflorum, together with three known saponins, including platycodin D, deapio platycoside E and platycoside E. The structure of the new compound, named 16-oxo-platycodin D, was elucidated on the basis of spectroscopic data.
A new triterpenoid saponin, 3-O-β-D-glucopyranosyl 16-oxo-platycodigenin 28-O-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyra-nosyl ester, was isolated from the roots of Platycodon grandiflorum, together with three known saponins, including platycodin D, deapio platycoside E and platycoside E. The structure of the new compound, named 16-oxo-platycodin D, was elucidated on the basis of spectroscopic data.
2007, 18(3): 309-312
doi: 10.1016/j.cclet.2006.12.025
Abstract:
The electrical oscillations across a liquid membrane in water/oil/water system was studied with octanol as oil phase by introducing two opposite charged surfactants in oil and aqueous phase, respectively. The sustained and rhythmic oscillation was observed. To a certain extent, the features of the oscillation (e.g. induction time, frequency, life time and orientation of the pulse pikes) strongly depend on the property of surfactant, dissolved in octanol. The mechanism may be explained by the formation and destruction of dual-ion surfactant membrane accompanying with emulsification at the interface and considering the coupling effect of diffusion and associated reaction in the vicinity of the interface.
The electrical oscillations across a liquid membrane in water/oil/water system was studied with octanol as oil phase by introducing two opposite charged surfactants in oil and aqueous phase, respectively. The sustained and rhythmic oscillation was observed. To a certain extent, the features of the oscillation (e.g. induction time, frequency, life time and orientation of the pulse pikes) strongly depend on the property of surfactant, dissolved in octanol. The mechanism may be explained by the formation and destruction of dual-ion surfactant membrane accompanying with emulsification at the interface and considering the coupling effect of diffusion and associated reaction in the vicinity of the interface.
2007, 18(3): 313-315
doi: 10.1016/j.cclet.2007.01.021
Abstract:
Stable adsorption and direct electrochemistry of glucose oxidase (GOx) occurred on nitric acid (HNO3)-treated multi-walled carbon nanotubes (MWNTs) instead of as-received MWNTs, demonstrating the critical roles of oxygen-containing groups in stable adsorption and direct electrochemistry of GOx on carbon nanotubes (CNTs).
Stable adsorption and direct electrochemistry of glucose oxidase (GOx) occurred on nitric acid (HNO3)-treated multi-walled carbon nanotubes (MWNTs) instead of as-received MWNTs, demonstrating the critical roles of oxygen-containing groups in stable adsorption and direct electrochemistry of GOx on carbon nanotubes (CNTs).
2007, 18(3): 316-318
doi: 10.1016/j.cclet.2007.01.032
Abstract:
A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase rnicroextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL-1 for both strychnine and brucine in human urine sample. The detection limits (S/N=3:1) for strychnine and brucine were 1 ng mL-1 and 2 ng mL-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.
A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase rnicroextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL-1 for both strychnine and brucine in human urine sample. The detection limits (S/N=3:1) for strychnine and brucine were 1 ng mL-1 and 2 ng mL-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.
2007, 18(3): 319-321
doi: 10.1016/j.cclet.2007.01.033
Abstract:
1H NMR has been used to determine the 2-, 4-vinyl orientation of heme active site from oxidized mouse neuroglobin (mNgb).The NOEs between 3-methyl and Hα, Hβ of 2-vinyl, together with the NOEs between 5-methyl and Hα, Hβ of 4-vinyl, allowed the unambiguous determination of trans and cis orientations for the 2-and 4-vinyl groups in the mNgb, respectively.
1H NMR has been used to determine the 2-, 4-vinyl orientation of heme active site from oxidized mouse neuroglobin (mNgb).The NOEs between 3-methyl and Hα, Hβ of 2-vinyl, together with the NOEs between 5-methyl and Hα, Hβ of 4-vinyl, allowed the unambiguous determination of trans and cis orientations for the 2-and 4-vinyl groups in the mNgb, respectively.
2007, 18(3): 322-324
doi: 10.1016/j.cclet.2007.01.037
Abstract:
Molecularly imprinted polymers (MIPs), using (S)-naproxen as template and the combination of butyl methacrylate (BMA) and MAA (1:1 molar ratio) as functional monomers were synthesized by an in situ polymerization reaction. The rendered monolithic column was evaluated in HPLC mode. The result showed that the monolithic MIPs with the combination of two monomers produced better chiral resolution of rac-naproxen (Rs=1.55) and column efficiencies of imprinted molecules (N=2860 plates/m)than that with pure MAA.
Molecularly imprinted polymers (MIPs), using (S)-naproxen as template and the combination of butyl methacrylate (BMA) and MAA (1:1 molar ratio) as functional monomers were synthesized by an in situ polymerization reaction. The rendered monolithic column was evaluated in HPLC mode. The result showed that the monolithic MIPs with the combination of two monomers produced better chiral resolution of rac-naproxen (Rs=1.55) and column efficiencies of imprinted molecules (N=2860 plates/m)than that with pure MAA.
2007, 18(3): 325-328
doi: 10.1016/j.cclet.2007.01.034
Abstract:
Modified pectin cross-linked with adipic acid, was synthesized and used for heavy metal removal from wastewater. SEM and FrIR were used to investigate its structure and morphology. The modified pectin had a rough, porous phase covered with carboxy groups, resulting a high adsorption capacity. And at the room temperature, the saturated loading capacity for Pb2+, Cu2+ and Zn2+ reached 1.82 mmol/g, 1.794 mmol/g and 0.964 mmol/g, respectively. The results proved its potential application to remove of the heavy metal.
Modified pectin cross-linked with adipic acid, was synthesized and used for heavy metal removal from wastewater. SEM and FrIR were used to investigate its structure and morphology. The modified pectin had a rough, porous phase covered with carboxy groups, resulting a high adsorption capacity. And at the room temperature, the saturated loading capacity for Pb2+, Cu2+ and Zn2+ reached 1.82 mmol/g, 1.794 mmol/g and 0.964 mmol/g, respectively. The results proved its potential application to remove of the heavy metal.
2007, 18(3): 329-332
doi: 10.1016/j.cclet.2007.01.004
Abstract:
A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl-KCl (weight ratio is 1:1) electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.
A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl-KCl (weight ratio is 1:1) electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.
2007, 18(3): 333-336
doi: 10.1016/j.cclet.2007.01.026
Abstract:
A new europium(Ⅲ) complex, tris(dibenzoylmethanate){1-[9-hexyl-9-carbazole]-2-(2-pyridyl)-benzimidazole]europium(Ⅲ) [Eu(DBM)3(CPyBM)] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic (PV) device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm2. Compared with the previous reported devices based on Eu(Ⅲ) complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.
A new europium(Ⅲ) complex, tris(dibenzoylmethanate){1-[9-hexyl-9-carbazole]-2-(2-pyridyl)-benzimidazole]europium(Ⅲ) [Eu(DBM)3(CPyBM)] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic (PV) device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm2. Compared with the previous reported devices based on Eu(Ⅲ) complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.
2007, 18(3): 337-340
doi: 10.1016/j.cclet.2007.01.006
Abstract:
LiFePO4/C was synthesized by high temperature solid-state method with cheap Fe2O3, LiH2PO4 and glucose as raw materials in absence of inert gas. The sample had ordered olivine-type structure other impurities characterized by the test of X-ray diffraction(XRD). The charge-discharge test showed the sample could demonstrate 120.5 mAh/g at 0.2C rate with good cyclic capability. The powder microelectrode cyclic voltammetry test indicated that the redox process of the sample had good reversibility.
LiFePO4/C was synthesized by high temperature solid-state method with cheap Fe2O3, LiH2PO4 and glucose as raw materials in absence of inert gas. The sample had ordered olivine-type structure other impurities characterized by the test of X-ray diffraction(XRD). The charge-discharge test showed the sample could demonstrate 120.5 mAh/g at 0.2C rate with good cyclic capability. The powder microelectrode cyclic voltammetry test indicated that the redox process of the sample had good reversibility.
2007, 18(3): 341-344
doi: 10.1016/j.cclet.2006.12.018
Abstract:
The surface-grafted titanium MCM-41 materials were prepared by anchoring titanocene onto the inner walls of MCM-41. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption isotherm and diffuse reflectance UV-visible (UV-vis) spectroscopies. The catalytic properties of Ti-MCM-41 were tested in oxidation of 4-tert-butyltoluene with tert-butylhydroperoxide (TBHP) in liquid phase. MCM-41 with loading 4.8 mol% Ti gave the maximal conversions of 23.6% of 4-tert-butyltoluene with a complete selectivity to 4-tert-butylbenzaldehyde.
The surface-grafted titanium MCM-41 materials were prepared by anchoring titanocene onto the inner walls of MCM-41. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption isotherm and diffuse reflectance UV-visible (UV-vis) spectroscopies. The catalytic properties of Ti-MCM-41 were tested in oxidation of 4-tert-butyltoluene with tert-butylhydroperoxide (TBHP) in liquid phase. MCM-41 with loading 4.8 mol% Ti gave the maximal conversions of 23.6% of 4-tert-butyltoluene with a complete selectivity to 4-tert-butylbenzaldehyde.
2007, 18(3): 345-348
doi: 10.1016/j.cclet.2007.01.016
Abstract:
The ring patterns of calcium oxalate crystals were induced by domains in Langmuir-Blodgett (LB) films of dipalmitoylpho-sphatidylcholine (DPPC). The result was explained by the defects at the ring boundaries of liquid condensed (LC) and liquid expanded (LE) phases of LB film. These boundaries could provide less free energy and much more nucleating sites for COM crystals.
The ring patterns of calcium oxalate crystals were induced by domains in Langmuir-Blodgett (LB) films of dipalmitoylpho-sphatidylcholine (DPPC). The result was explained by the defects at the ring boundaries of liquid condensed (LC) and liquid expanded (LE) phases of LB film. These boundaries could provide less free energy and much more nucleating sites for COM crystals.
2007, 18(3): 349-351
doi: 10.1016/j.cclet.2006.12.015
Abstract:
The oxidative coupling reaction of 2,6-dimethylphenol with H2O2 catalyzed by a copper(Ⅱ) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3',5,5'-tetramethyl-4,4'-diphenoquinone (DPQ) was studied. Rate constant k2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.
The oxidative coupling reaction of 2,6-dimethylphenol with H2O2 catalyzed by a copper(Ⅱ) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3',5,5'-tetramethyl-4,4'-diphenoquinone (DPQ) was studied. Rate constant k2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.
2007, 18(3): 352-354
doi: 10.1016/j.cclet.2007.01.019
Abstract:
Nonmechanical pumping of liquids is of key importance for applications from the biomedical microfluidic chip to drug delivery systems. In this paper, a new electrokinetic pump (EOP) system with polycarbonate nanochannel membrane sandwiched between two membrane holders was constructed. The pump was tested with water and phosphate buffer at 1-6 V applied voltage, the maximum pressure and flow rate are 0.32 MPa (3.2 atm) and 4.2 μL/min for phosphate buffer, respectively. This proof-of-concept pump shows its potential use for drugs or chemical agents delivery by the usage of different membrane materials.
Nonmechanical pumping of liquids is of key importance for applications from the biomedical microfluidic chip to drug delivery systems. In this paper, a new electrokinetic pump (EOP) system with polycarbonate nanochannel membrane sandwiched between two membrane holders was constructed. The pump was tested with water and phosphate buffer at 1-6 V applied voltage, the maximum pressure and flow rate are 0.32 MPa (3.2 atm) and 4.2 μL/min for phosphate buffer, respectively. This proof-of-concept pump shows its potential use for drugs or chemical agents delivery by the usage of different membrane materials.
2007, 18(3): 355-356
doi: 10.1016/j.cclet.2007.01.017
Abstract:
For better understanding the chemical or biological information of ZNF191 (243-368), we expressed the fusion protein of GST and ZNF191(243-368), and used it to obtain the binding DNA sequence of this zinc finger protein. But in the process of expression and purification, we found this fusion protein slowly degradated. For resolving this problem, we simultaneously added charged amino acids L-Arg and L-Glu to the solution of fusion protein, and demonstrated that this method can dramatically increase the stability of this fusion protein. This method can make the fusion protein suitable for the continuous works, especially for situations where high protein concentration and long-term stability without precipitate and degradation of protein are required.
For better understanding the chemical or biological information of ZNF191 (243-368), we expressed the fusion protein of GST and ZNF191(243-368), and used it to obtain the binding DNA sequence of this zinc finger protein. But in the process of expression and purification, we found this fusion protein slowly degradated. For resolving this problem, we simultaneously added charged amino acids L-Arg and L-Glu to the solution of fusion protein, and demonstrated that this method can dramatically increase the stability of this fusion protein. This method can make the fusion protein suitable for the continuous works, especially for situations where high protein concentration and long-term stability without precipitate and degradation of protein are required.
2007, 18(3): 357-360
doi: 10.1016/j.cclet.2006.12.028
Abstract:
The inhibitory mechanism of copper(Ⅱ) on the aggregation of amyloid β-peptide (Aβ) was investigated by molecular dynamics simulations. The binding mode of copper(Ⅱ) with Aβ is characterized by the imidazole nitrogen atom, Nπ, of the histidine residue H13,acting as the anchoring site, and the backbone's deprotoned amide nitrogen atoms as the main binding sites. Drove by the coordination bonds and their induced hydrogen bond net, the conformations of Aβ converted from β-sheet non-β-sheet conformations, which destabilized the aggregation of Aβ into fibrils.
The inhibitory mechanism of copper(Ⅱ) on the aggregation of amyloid β-peptide (Aβ) was investigated by molecular dynamics simulations. The binding mode of copper(Ⅱ) with Aβ is characterized by the imidazole nitrogen atom, Nπ, of the histidine residue H13,acting as the anchoring site, and the backbone's deprotoned amide nitrogen atoms as the main binding sites. Drove by the coordination bonds and their induced hydrogen bond net, the conformations of Aβ converted from β-sheet non-β-sheet conformations, which destabilized the aggregation of Aβ into fibrils.
2007, 18(3): 361-364
doi: 10.1016/j.cclet.2007.01.010
Abstract:
Covalent modification of shortened multiwalled carbon nanotubes (MWNTs) with a natural low molecular weight chitosan (LMCS) was accomplished by the nucleophilic substitution reaction. The LMCS modified MWNTs (MWNT-LMCS) were characterized by FTIR, solid-state 13C NMR, and XPS spectroscopies, thermogravimetric analysis, and transmission electron microscopy. The results revealed that amino and primary hydroxyl groups of the LMCS participated mainly in the formation of the MWNT-LMCS conjugates. The MWNT-LMCS consists of 58 wt.% LMCS, and about four molecular chains of the LMCS were attached to 1000 carbon atoms of the nanotube sidewalls. As a novel derivative of the MWNTs, the MWNT-LMCS not only solved in DMF, DMAc and DMSO, but also in aqueous acetic acid solution.
Covalent modification of shortened multiwalled carbon nanotubes (MWNTs) with a natural low molecular weight chitosan (LMCS) was accomplished by the nucleophilic substitution reaction. The LMCS modified MWNTs (MWNT-LMCS) were characterized by FTIR, solid-state 13C NMR, and XPS spectroscopies, thermogravimetric analysis, and transmission electron microscopy. The results revealed that amino and primary hydroxyl groups of the LMCS participated mainly in the formation of the MWNT-LMCS conjugates. The MWNT-LMCS consists of 58 wt.% LMCS, and about four molecular chains of the LMCS were attached to 1000 carbon atoms of the nanotube sidewalls. As a novel derivative of the MWNTs, the MWNT-LMCS not only solved in DMF, DMAc and DMSO, but also in aqueous acetic acid solution.
2007, 18(3): 365-368
doi: 10.1016/j.cclet.2007.01.001
Abstract:
A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy films through vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.
A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy films through vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.
2007, 18(3): 369-372
doi: 10.1016/j.cclet.2007.01.002
Abstract:
The water-soluble CdS nanoparticles were synthesized in aqueous solution. A novel fluorescence resonance energy transfer(FRET) system with CdS nanoparticles as energy donors and 3,3'-diethyl-oxadicarbocyanine iodide (DOCAI) dyes as energy accepter has been developed.
The water-soluble CdS nanoparticles were synthesized in aqueous solution. A novel fluorescence resonance energy transfer(FRET) system with CdS nanoparticles as energy donors and 3,3'-diethyl-oxadicarbocyanine iodide (DOCAI) dyes as energy accepter has been developed.
