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2009 Volume 20 Issue 3
2009, 20(3): 253-255
doi: 10.1016/j.cclet.2008.11.026
Abstract:
A new method for introduction ω-side chain of prostanoid was described in this note. Starting from acid chloride (3), via Barton radical reaction, a trans α,β-unsaturated ketone sython was introduced.
A new method for introduction ω-side chain of prostanoid was described in this note. Starting from acid chloride (3), via Barton radical reaction, a trans α,β-unsaturated ketone sython was introduced.
2009, 20(3): 256-260
doi: 10.1016/j.cclet.2008.11.015
Abstract:
The new chromium (VI) oxidizing reagent isoquinolinium bromochromate (IQBC) was prepared and characterized. The IQBC has been found to be stable and an efficient solid reagent which can be easily prepared in good yield. It act as an efficient brominating reagent for hydroxylated aromatic compounds as well as good oxidizing reagent for the conversion of alcohols to carbonyl compounds in good to excellent yield. The synthesized isoquinolinium bromochromate is more ideal reagent, with number of specification including: higher yield, mild conditions and easy preparation. The results obtained with isoquinolinium bromochromate are satisfactory and suggest that the reagent has few advantages over the existing chromium (VI) reagents.
The new chromium (VI) oxidizing reagent isoquinolinium bromochromate (IQBC) was prepared and characterized. The IQBC has been found to be stable and an efficient solid reagent which can be easily prepared in good yield. It act as an efficient brominating reagent for hydroxylated aromatic compounds as well as good oxidizing reagent for the conversion of alcohols to carbonyl compounds in good to excellent yield. The synthesized isoquinolinium bromochromate is more ideal reagent, with number of specification including: higher yield, mild conditions and easy preparation. The results obtained with isoquinolinium bromochromate are satisfactory and suggest that the reagent has few advantages over the existing chromium (VI) reagents.
2009, 20(3): 261-264
doi: 10.1016/j.cclet.2008.10.024
Abstract:
A new method for preparation of diaminonitrile compounds is reported. In this method primary aliphatic diamine compounds were condensed with two equivalents of benzaldehyde and sodium cyanide in presence of an aqueous solution of sodium hydrogensulfite under mild conditions. This method provides an efficient, convenient and practical method for the syntheses of diaminonitrile compounds and the products are easily isolated. The prepared new compounds were characterized by elemental analysis, IR, NMR spectroscopies and mass spectrometry.
A new method for preparation of diaminonitrile compounds is reported. In this method primary aliphatic diamine compounds were condensed with two equivalents of benzaldehyde and sodium cyanide in presence of an aqueous solution of sodium hydrogensulfite under mild conditions. This method provides an efficient, convenient and practical method for the syntheses of diaminonitrile compounds and the products are easily isolated. The prepared new compounds were characterized by elemental analysis, IR, NMR spectroscopies and mass spectrometry.
2009, 20(3): 265-268
doi: 10.1016/j.cclet.2008.11.028
Abstract:
A novel type of molecular tweezers with different chiral center and cleft has been designed and prepared by using α-hyodeoxycholic acid as spacer and D/L-amino acid methyl ester as chiral arm attached at 3-position. Their structures were elucidated by 1H NMR, FTIR and elemental analysis. Their recognition properties for various D/L-amino acid methyl esters were also investigated. The preliminary results indicated that these chiral single-armed molecular tweezers exhibited good recognition ability for D/L-amino acid methyl esters with high association constant (up to 5.24×103 L mol-1).
A novel type of molecular tweezers with different chiral center and cleft has been designed and prepared by using α-hyodeoxycholic acid as spacer and D/L-amino acid methyl ester as chiral arm attached at 3-position. Their structures were elucidated by 1H NMR, FTIR and elemental analysis. Their recognition properties for various D/L-amino acid methyl esters were also investigated. The preliminary results indicated that these chiral single-armed molecular tweezers exhibited good recognition ability for D/L-amino acid methyl esters with high association constant (up to 5.24×103 L mol-1).
2009, 20(3): 269-270
doi: 10.1016/j.cclet.2008.11.031
Abstract:
Anovelmethod for synthesis of 2-butyl-5-chloro-3H-imidazole-4-carbaldehyde 2, a key intermediate of Losartan was reported. The compound 2 was synthesized fromstarting material dimethyl malonate 6 and n-valeronitrile 8 by six steps with an overall yield of 40%.The key step including the reaction of compound 5 with POCl3/DMF followed by hydrolysis to give compound 2 with the yield of 68%.
Anovelmethod for synthesis of 2-butyl-5-chloro-3H-imidazole-4-carbaldehyde 2, a key intermediate of Losartan was reported. The compound 2 was synthesized fromstarting material dimethyl malonate 6 and n-valeronitrile 8 by six steps with an overall yield of 40%.The key step including the reaction of compound 5 with POCl3/DMF followed by hydrolysis to give compound 2 with the yield of 68%.
2009, 20(3): 271-274
doi: 10.1016/j.cclet.2008.11.025
Abstract:
2-Amino-2-chromenes are class of heterocycles that posses considerable interest as pigments, cosmetics, potential agrochemicals and being the main constituents of many natural products. Although, they are generally prepared either under conventional heating, benign reagents or very recently, a three component condensation in poly-ethylene glycol-water in the presence of nanosized magnesium oxide, most of these methods require prolonged reaction time, reagents in stoichiometric amounts and generate moderate yields of products. Microwave technique performs a better yield in a short reaction time (85-94%;5-8 min). Also, three-component one step reaction is of great interest for cost savings from the point of raw materials, energy and time. A combination between both techniques will be attractive for researchers in that field.
2-Amino-2-chromenes are class of heterocycles that posses considerable interest as pigments, cosmetics, potential agrochemicals and being the main constituents of many natural products. Although, they are generally prepared either under conventional heating, benign reagents or very recently, a three component condensation in poly-ethylene glycol-water in the presence of nanosized magnesium oxide, most of these methods require prolonged reaction time, reagents in stoichiometric amounts and generate moderate yields of products. Microwave technique performs a better yield in a short reaction time (85-94%;5-8 min). Also, three-component one step reaction is of great interest for cost savings from the point of raw materials, energy and time. A combination between both techniques will be attractive for researchers in that field.
2009, 20(3): 275-278
doi: 10.1016/j.cclet.2008.11.010
Abstract:
Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl-3-methylimidazolium tetrafluoroborate (abbreviated as [cmmim][BF4]) as catalyst was successfully performed. The yields of the target compounds were 80-92%, the purities were 96-98%. The catalyst could be recovered and reused for at least six times without significant loss in activity.
Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl-3-methylimidazolium tetrafluoroborate (abbreviated as [cmmim][BF4]) as catalyst was successfully performed. The yields of the target compounds were 80-92%, the purities were 96-98%. The catalyst could be recovered and reused for at least six times without significant loss in activity.
2009, 20(3): 279-282
doi: 10.1016/j.cclet.2008.12.005
Abstract:
Ionic liquids [Bmim]BF4 and [Bpy]BF4 were employed as environmentally benign media in Doebner condensation to synthesize α,β-unsaturated carboxylic acid. The good results showed that [Bmim]BF4 and [Bpy]BF4 were efficient media for Doebner condensation, which could be recycled easily. The highest yields could reach 93%and 90%in [Bmim]BF4 and [Bpy]BF4, respectively.
Ionic liquids [Bmim]BF4 and [Bpy]BF4 were employed as environmentally benign media in Doebner condensation to synthesize α,β-unsaturated carboxylic acid. The good results showed that [Bmim]BF4 and [Bpy]BF4 were efficient media for Doebner condensation, which could be recycled easily. The highest yields could reach 93%and 90%in [Bmim]BF4 and [Bpy]BF4, respectively.
2009, 20(3): 283-287
doi: 10.1016/j.cclet.2008.11.033
Abstract:
2,4,5-Triarylimidazoles could be obtained in excellent yields by the one-pot three-component condensation of benzil/benzoin,aldehydes and ammonium acetate in the presence of catalytic amount of the inexpensive, readily available and non-toxic ceric (Ⅳ) ammonium nitrate (CAN) in aqueous media under ultrasound at room temperature. In this reaction the products were obtained in short reaction time and easy operation under mild conditions.
2,4,5-Triarylimidazoles could be obtained in excellent yields by the one-pot three-component condensation of benzil/benzoin,aldehydes and ammonium acetate in the presence of catalytic amount of the inexpensive, readily available and non-toxic ceric (Ⅳ) ammonium nitrate (CAN) in aqueous media under ultrasound at room temperature. In this reaction the products were obtained in short reaction time and easy operation under mild conditions.
2009, 20(3): 288-291
doi: 10.1016/j.cclet.2008.11.027
Abstract:
Cyclopropanecarboxylic acid or 2,2-dimethyl cyclopropanecarboxylic acid was used as a leading compound for its biological activity. Six new N-(substituted) cyclopropanecarboxyl-N'-pyridin-2-yl thioureas were prepared. Compound 5 was obtained by oxidizing cyclization of compound 4 in the presence of bromine in chloroform solution. The structures of 4 and 5 were confirmed by 1H NMR and elemental analysis. The preliminary biological tests indicate that compound 4b and 4e have excellent herbicidal activity, and compound 4c and 4f have excellent fungicidal activity.
Cyclopropanecarboxylic acid or 2,2-dimethyl cyclopropanecarboxylic acid was used as a leading compound for its biological activity. Six new N-(substituted) cyclopropanecarboxyl-N'-pyridin-2-yl thioureas were prepared. Compound 5 was obtained by oxidizing cyclization of compound 4 in the presence of bromine in chloroform solution. The structures of 4 and 5 were confirmed by 1H NMR and elemental analysis. The preliminary biological tests indicate that compound 4b and 4e have excellent herbicidal activity, and compound 4c and 4f have excellent fungicidal activity.
2009, 20(3): 292-295
doi: 10.1016/j.cclet.2008.09.057
Abstract:
Ammonium metavanadate (10 mol%) was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles. It was used as an oxidizing agent for the condensation of o-phenylenediamine with different substituted aryl aldehydes at room temperature in ethanol. The method was proved to be simple, convenient and the product was isolated with good yields (79-91%).
Ammonium metavanadate (10 mol%) was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles. It was used as an oxidizing agent for the condensation of o-phenylenediamine with different substituted aryl aldehydes at room temperature in ethanol. The method was proved to be simple, convenient and the product was isolated with good yields (79-91%).
2009, 20(3): 296-299
doi: 10.1016/j.cclet.2008.11.029
Abstract:
A series of thiourea derivatives have been synthesized. Their structures were confirmed by MS and 1H NMR. Several compounds showed potent activities as antagonists of CCR4 receptor.
A series of thiourea derivatives have been synthesized. Their structures were confirmed by MS and 1H NMR. Several compounds showed potent activities as antagonists of CCR4 receptor.
2009, 20(3): 300-301
doi: 10.1016/j.cclet.2008.12.001
Abstract:
Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltrichlorosilane, allyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by 1H NMR, IR, MS.
Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltrichlorosilane, allyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by 1H NMR, IR, MS.
2009, 20(3): 302-305
doi: 10.1016/j.cclet.2008.11.012
Abstract:
A series of novel nitric oxide-donating derivatives (7a-e, 8a-e) were synthesized by coupling furoxan and nitric oxide with irbesartan analogue and their cytotoxicity against BEL7402 cells in vitro were evaluated by MTT method. It was found that 8c exhibits the most cytotoxic activities with IC50 value of 12.5 μmol/L. The hybrids of AT1 antagonist and nitric oxide donor appear to have beneficial effects on antitumor.
A series of novel nitric oxide-donating derivatives (7a-e, 8a-e) were synthesized by coupling furoxan and nitric oxide with irbesartan analogue and their cytotoxicity against BEL7402 cells in vitro were evaluated by MTT method. It was found that 8c exhibits the most cytotoxic activities with IC50 value of 12.5 μmol/L. The hybrids of AT1 antagonist and nitric oxide donor appear to have beneficial effects on antitumor.
2009, 20(3): 306-309
doi: 10.1016/j.cclet.2008.11.008
Abstract:
A novel approach to the synthesis of 2,2',3,3'-biphenyltetracarboxylic dianhydride is described. The target compound was prepared by a nickel-catalyzed coupling reaction of dimethy 3-chlorophthalate (3-DMCP) for 4 h at 70-80℃, followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid, with overall yield of 68%. The structures of the products were characterized by IR, 1H NMR and 13C NMR respectively.
A novel approach to the synthesis of 2,2',3,3'-biphenyltetracarboxylic dianhydride is described. The target compound was prepared by a nickel-catalyzed coupling reaction of dimethy 3-chlorophthalate (3-DMCP) for 4 h at 70-80℃, followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid, with overall yield of 68%. The structures of the products were characterized by IR, 1H NMR and 13C NMR respectively.
2009, 20(3): 310-313
doi: 10.1016/j.cclet.2008.11.021
Abstract:
Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malonates affording the desired products in up to 95% yield with excellent enantioselectivities (up to 97% ee).
Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malonates affording the desired products in up to 95% yield with excellent enantioselectivities (up to 97% ee).
2009, 20(3): 314-316
doi: 10.1016/j.cclet.2008.11.007
Abstract:
One practical and industrial procedure for preparation of 5-hydroxymethyluracil has been developed. This method has the advantage of facile operation, low cost and stable yield.
One practical and industrial procedure for preparation of 5-hydroxymethyluracil has been developed. This method has the advantage of facile operation, low cost and stable yield.
2009, 20(3): 317-319
doi: 10.1016/j.cclet.2008.11.009
Abstract:
A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR.
A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR.
2009, 20(3): 320-321
doi: 10.1016/j.cclet.2008.12.003
Abstract:
A new flavonoid glucoside with a known one was isolated from the leaves of Cassia angustifolia. Based on the spectral analysis,including MS, 1H NMR, 13C NMR, DEPT, 1H-1HCOSY, HMQC, HMBC and NOSEY, their chemical structures were determined as kaempferol-3-O-[(6'''-O-trans-sinnapoyl)-β-D-glucopyranosyl (1→6)]-β-D-glucopyranoside 1 and apigenin-6,8-di-C-glycoside 2.
A new flavonoid glucoside with a known one was isolated from the leaves of Cassia angustifolia. Based on the spectral analysis,including MS, 1H NMR, 13C NMR, DEPT, 1H-1HCOSY, HMQC, HMBC and NOSEY, their chemical structures were determined as kaempferol-3-O-[(6'''-O-trans-sinnapoyl)-β-D-glucopyranosyl (1→6)]-β-D-glucopyranoside 1 and apigenin-6,8-di-C-glycoside 2.
Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry
2009, 20(3): 322-325
doi: 10.1016/j.cclet.2008.10.045
Abstract:
The inclusion interaction between berberine hydrochloride (BRH) and cucurbit[7] (CB[7]) has been studied by spectrofluorimetry.The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57×104 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself.Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2-2×103 ng/mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.
The inclusion interaction between berberine hydrochloride (BRH) and cucurbit[7] (CB[7]) has been studied by spectrofluorimetry.The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57×104 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself.Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2-2×103 ng/mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.
2009, 20(3): 326-329
doi: 10.1016/j.cclet.2008.11.013
Abstract:
A new fluorescent probe (BPb1) for Pb2+ has been synthesized, where diethanolamine (receptor) is linked with 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) (fluorophore) via a methylene group (spacer). The absorption (496 nm) and emission (505 nm) wavelengths are in visible range. The fluorescence quantum yields of the lead-free and lead-bound states of BPb1 in acetonitrile are 0.013 and 0.693, respectively. The large chelation enhanced fluorescence effect (CHEF) with Pb2+ can be explained by the blocking of the photoinduced electron transfer (PET) process.
A new fluorescent probe (BPb1) for Pb2+ has been synthesized, where diethanolamine (receptor) is linked with 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) (fluorophore) via a methylene group (spacer). The absorption (496 nm) and emission (505 nm) wavelengths are in visible range. The fluorescence quantum yields of the lead-free and lead-bound states of BPb1 in acetonitrile are 0.013 and 0.693, respectively. The large chelation enhanced fluorescence effect (CHEF) with Pb2+ can be explained by the blocking of the photoinduced electron transfer (PET) process.
2009, 20(3): 330-333
doi: 10.1016/j.cclet.2008.11.020
Abstract:
The interaction between HⅣ-1 DNA and five cyclic peptides (CP1-CP5) was investigated using electrospray ionization mass spectrometry (ESI-MS). It revealed that CP1 [c(Ala-Tyr-Leu-Ala-Gly)] and CP4 [c(Pro-D-Tyr-Leu-D-Ala-Gly)] have the higher binding affinity with the duplex DNA among the five cyclic peptides.
The interaction between HⅣ-1 DNA and five cyclic peptides (CP1-CP5) was investigated using electrospray ionization mass spectrometry (ESI-MS). It revealed that CP1 [c(Ala-Tyr-Leu-Ala-Gly)] and CP4 [c(Pro-D-Tyr-Leu-D-Ala-Gly)] have the higher binding affinity with the duplex DNA among the five cyclic peptides.
2009, 20(3): 334-338
doi: 10.1016/j.cclet.2008.12.006
Abstract:
This paper described a novel method for the preconcentration of Pb(Ⅱ) using microcrystalline triphenylmethane loaded with quinolin-8-olate prior to the determination by flame atomic absorption spectrometry. Pb(Ⅱ) could be enriched by controlling appropriate condition. The preconcentration factor could reach to 200 and the detection limit of Pb(Ⅱ) was 0.074 μg/L. The recovery was in a range of 93.5-103% with relative standard deviation of 1.0-2.2%. The proposed method had been successfully applied to the determination of trace Pb(Ⅱ) in various water samples with satisfactory result.
This paper described a novel method for the preconcentration of Pb(Ⅱ) using microcrystalline triphenylmethane loaded with quinolin-8-olate prior to the determination by flame atomic absorption spectrometry. Pb(Ⅱ) could be enriched by controlling appropriate condition. The preconcentration factor could reach to 200 and the detection limit of Pb(Ⅱ) was 0.074 μg/L. The recovery was in a range of 93.5-103% with relative standard deviation of 1.0-2.2%. The proposed method had been successfully applied to the determination of trace Pb(Ⅱ) in various water samples with satisfactory result.
2009, 20(3): 339-343
doi: 10.1016/j.cclet.2008.12.008
Abstract:
Eight new macrocyclic complexes were synthesized by template reaction of 1,4-bis(3-aminopropoxy)butane with metal nitrate and 1,3-bis(2-formylphenyl)propane or 1,4-bis(2-formylphenyl)butane and their structures were proposed on the basis of elemental analysis, FTIR, UV-vis, molar conductivity measurements, 1H NMR and mass spectra. The metals to ligand molar ratios of the complexes were found to be 1:1. The complexes are 1:2 electrolytes for Pb(Ⅱ), Zn(Ⅱ) and Cd(Ⅱ) complexes and 1:3 electrolytes for La(Ⅲ) as shown by their molar conductivities (∧m) in DMSO at 10-3 mol L-1. Due to the existence of free ions in these complexes,such complexes are electrically conductive. The configurations of La(Ⅲ) and Pb(Ⅱ) were proposed to probably octahedral and Zn(Ⅱ) and Cd(Ⅱ) complexes were proposed to probably tetrahedral.
Eight new macrocyclic complexes were synthesized by template reaction of 1,4-bis(3-aminopropoxy)butane with metal nitrate and 1,3-bis(2-formylphenyl)propane or 1,4-bis(2-formylphenyl)butane and their structures were proposed on the basis of elemental analysis, FTIR, UV-vis, molar conductivity measurements, 1H NMR and mass spectra. The metals to ligand molar ratios of the complexes were found to be 1:1. The complexes are 1:2 electrolytes for Pb(Ⅱ), Zn(Ⅱ) and Cd(Ⅱ) complexes and 1:3 electrolytes for La(Ⅲ) as shown by their molar conductivities (∧m) in DMSO at 10-3 mol L-1. Due to the existence of free ions in these complexes,such complexes are electrically conductive. The configurations of La(Ⅲ) and Pb(Ⅱ) were proposed to probably octahedral and Zn(Ⅱ) and Cd(Ⅱ) complexes were proposed to probably tetrahedral.
2009, 20(3): 344-347
doi: 10.1016/j.cclet.2008.11.032
Abstract:
Mesoporous silica supported Cs2.5H0.5PW12O40 catalysts were prepared by impregnation method, and several silica supports with different pore size were utilized. N2 adsorption, XRD and ICP-AES techniques were utilized to characterize the silica supports and catalysts. XRD results showed that the dispersion of Cs2.5H0.5PW12 was better for the silica support with larger pore size. The catalytic activity results showed that the pore size played important role on the catalyst activity and the molecular weight of PTHF.When Cs2.5H0.5PW12O40 was dispersed on larger pore size silica support, the catalysts showed good performances for the synthesis of PTHF. The molecular weight of PTHF product on the sample in which Cs2.5H0.5PW12O40 was dispersed on larger pore support was higher than that on the catalyst with smaller pore support. The leaching amounts of the active components for the supported Cs2.5H0.5PW12O40 catalysts were much lower. After five reaction cycles, there were still good activities and stabilities for the supported Cs2.5H0.5PW12O40 catalysts with larger pore silica supports. These results were much better than those of the supported heteropolyacid H3PW12O40 catalyst.
Mesoporous silica supported Cs2.5H0.5PW12O40 catalysts were prepared by impregnation method, and several silica supports with different pore size were utilized. N2 adsorption, XRD and ICP-AES techniques were utilized to characterize the silica supports and catalysts. XRD results showed that the dispersion of Cs2.5H0.5PW12 was better for the silica support with larger pore size. The catalytic activity results showed that the pore size played important role on the catalyst activity and the molecular weight of PTHF.When Cs2.5H0.5PW12O40 was dispersed on larger pore size silica support, the catalysts showed good performances for the synthesis of PTHF. The molecular weight of PTHF product on the sample in which Cs2.5H0.5PW12O40 was dispersed on larger pore support was higher than that on the catalyst with smaller pore support. The leaching amounts of the active components for the supported Cs2.5H0.5PW12O40 catalysts were much lower. After five reaction cycles, there were still good activities and stabilities for the supported Cs2.5H0.5PW12O40 catalysts with larger pore silica supports. These results were much better than those of the supported heteropolyacid H3PW12O40 catalyst.
2009, 20(3): 348-351
doi: 10.1016/j.cclet.2008.11.018
Abstract:
A kind of catalyst, ammonium molybdate was developed in this paper to promote the curing reaction of bisphthalonitrile resins with aromatic amine as curing agent, and the catalytic effect was studied by differential scanning calorimetry (DSC), rheometric measurements and thermogravimetric analysis (TGA). The results indicated that the catalyst could improve the curing rate and increase the curing degree, which could be regulated by the content of the catalyst used in the reaction.
A kind of catalyst, ammonium molybdate was developed in this paper to promote the curing reaction of bisphthalonitrile resins with aromatic amine as curing agent, and the catalytic effect was studied by differential scanning calorimetry (DSC), rheometric measurements and thermogravimetric analysis (TGA). The results indicated that the catalyst could improve the curing rate and increase the curing degree, which could be regulated by the content of the catalyst used in the reaction.
2009, 20(3): 352-355
doi: 10.1016/j.cclet.2008.11.034
Abstract:
Novel Cu-Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2.
Novel Cu-Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2.
2009, 20(3): 356-357
doi: 10.1016/j.cclet.2008.11.014
Abstract:
Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.
Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.
2009, 20(3): 358-361
doi: 10.1016/j.cclet.2008.10.025
Abstract:
Multi-walled carbon nanotubes (MWCNTs) were coated with ZnO by a hydrothermal method. The resulting nanocomposites were mixed with the Nafion solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. To prevent the leak of Hb molecules of the biosensor, silica sol-gel film was coated on the surface of the Hb/ZnO-MWCNTs/Nafion electrode. The silica sol-gel/Hb/ZnO-MWCNTs/Nafion film exhibited a pair of well-defined, quasi-reversible redox peaks. This biosensor showed excellent electrocatalytic activity to H2O2. The sensitivity and apparent Michaelis-Menten constant of this Hb biosensor to H2O2 were 1.31 A/(M cm2) and 82.8 μmol/L, respectively, which indicated that Hb had high affinity to H2O2.
Multi-walled carbon nanotubes (MWCNTs) were coated with ZnO by a hydrothermal method. The resulting nanocomposites were mixed with the Nafion solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. To prevent the leak of Hb molecules of the biosensor, silica sol-gel film was coated on the surface of the Hb/ZnO-MWCNTs/Nafion electrode. The silica sol-gel/Hb/ZnO-MWCNTs/Nafion film exhibited a pair of well-defined, quasi-reversible redox peaks. This biosensor showed excellent electrocatalytic activity to H2O2. The sensitivity and apparent Michaelis-Menten constant of this Hb biosensor to H2O2 were 1.31 A/(M cm2) and 82.8 μmol/L, respectively, which indicated that Hb had high affinity to H2O2.
2009, 20(3): 362-365
doi: 10.1016/j.cclet.2008.11.016
Abstract:
β-Cyclodextrin/poly(γ-benzyl L-glutamate) (β-CD-PBLG) copolymers were synthesized by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLG-NCA) in N,N-dimethylformamide (DMF) initiated by mono-amino-β-cyclodextrin(H2N-β-CD). The structures of the copolymers were confirmed by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer micell solution, the diameter and the distribution of micelles were characterized by DLS. The results showed that BLG-NCA could be initiated by H2N-β-CD to produce copolymer. The nanomicells were formed by these copolymers in water.
β-Cyclodextrin/poly(γ-benzyl L-glutamate) (β-CD-PBLG) copolymers were synthesized by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLG-NCA) in N,N-dimethylformamide (DMF) initiated by mono-amino-β-cyclodextrin(H2N-β-CD). The structures of the copolymers were confirmed by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer micell solution, the diameter and the distribution of micelles were characterized by DLS. The results showed that BLG-NCA could be initiated by H2N-β-CD to produce copolymer. The nanomicells were formed by these copolymers in water.
2009, 20(3): 366-369
doi: 10.1016/j.cclet.2008.11.036
Abstract:
Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 Vof DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction or partly turned into solution, while for the gels with higher polyacrylamide concentration, a complete gel-sol transition was observed in a short time.
Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 Vof DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction or partly turned into solution, while for the gels with higher polyacrylamide concentration, a complete gel-sol transition was observed in a short time.
2009, 20(3): 370-373
doi: 10.1016/j.cclet.2008.12.010
Abstract:
A new 1D infinite neutral chain (Ph3SnO2SeOCH2CH3)n (1) based on organotin and selenious acid monoethyl ester has been synthesized successfully and characterized by IR, elemental analysis, and X-ray single-crystal diffraction. In the compound 1, the Sn atom exists in slightly distorted trigonal bipyramidal geometry and the Se center is tri-coordinated with a distorted pyramidal arrangement. It is noted that the synthesis is facile and selenium oxide is directly introduced into synthesis route replacing organoseleninic acid under room temperature.
A new 1D infinite neutral chain (Ph3SnO2SeOCH2CH3)n (1) based on organotin and selenious acid monoethyl ester has been synthesized successfully and characterized by IR, elemental analysis, and X-ray single-crystal diffraction. In the compound 1, the Sn atom exists in slightly distorted trigonal bipyramidal geometry and the Se center is tri-coordinated with a distorted pyramidal arrangement. It is noted that the synthesis is facile and selenium oxide is directly introduced into synthesis route replacing organoseleninic acid under room temperature.
2009, 20(3): 374-377
doi: 10.1016/j.cclet.2008.12.007
Abstract:
The insertion reactions of germylene into C-Cl bond of 1-chorobenzene have been explored using density functional theory.Five germylene species have been chosen for systematically studying. All the stationary points were determined at the B3LYP/6-311+G (d, p) level of the theory. The results show that, the smaller the △EST of germylene, the lower the barrier height, and the electropositive substituents on the germylene can increase the reaction activity and exothermicity of insertion into C-Cl bond of 1-chorobenzene.
The insertion reactions of germylene into C-Cl bond of 1-chorobenzene have been explored using density functional theory.Five germylene species have been chosen for systematically studying. All the stationary points were determined at the B3LYP/6-311+G (d, p) level of the theory. The results show that, the smaller the △EST of germylene, the lower the barrier height, and the electropositive substituents on the germylene can increase the reaction activity and exothermicity of insertion into C-Cl bond of 1-chorobenzene.
