查看更多>>摘要：" Chemical Research in Chinese Universities", sponsored by Jilin University mandated by the Ministry of Education of P. R. China and published by Higher Education Press in China, is a comprehensive academic journal in the field of chemistry. The journal contains original papers, research notes, letters and reviews written by faculty members, scientific researchers, postgraduates and graduate students of universities and colleges, and scientific institutes all over China and the world, and reports the latest and most creative results of important fundamental research in all aspects of chemistry and of developments with significant consequences across subdisciplines.
查看更多>>摘要：Two new supramolecular polymers [M(2-NH_2py)_2(ox)] [M = Co (1) , Ni (2) ; 2-NH_2py = 2-aminopyridine; ox = oxalate] were hydrothermally synthesized and characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. The isomorphic compounds 1 and 2 both possess one-dimensional zigzag chain structures, which are composed of [M(2-NH_2py)_2]~(2+) units bridged by tetradentate oxalate ligands to form three-dimensional supramolecular network via the C-H…O hydrogen bonds and π-π stacking interactions. Compound 1 displays antiferromag-netic interaction.
查看更多>>摘要：The tide complex [NH_3CH_2CH(NH_2)CH_3]_2[M(VI)O_2(OC_6H_4O)_2](M=Mo_(0.6)W_(0.4)) was synthesized via a simple solution-phase chemical route. The determination of single crystal X-ray diffraction revealed that the title compound is crystallized in a monoclinic system with P2( 1)/n space group, α = 1.0913(10) nm, b = 1. 0442(10) nm, c = l. 8842(19) nm, α = 90°, β = 96. 530( 17)°, γ = 90° , Z=4, and V = 2. 133(4) nm~3. The mononuclear anionic unit [M(VI)O_2(OC_6H_4O)_2]~(2-) displays chiral pseudo-octahedral [MO_6] coordination geometry and is linked by chiral cations via hydrogen bond and π-π stacking interaction. The transmission electron microscopy images show that the title complex is comprised of nano-particles with diameters ranging from 20 to 50 nm. The NMR study shows the H downfield chemical shifts of [NH_3CH_aH_bCH(NH_2)CH_3]~- cations in the title complex when it is mixed with adenosine-triphosphate(ATP) , and the chemical shift difference between Ha and Hb is increased greatly, and most of the catecholate ligands dissociate from the central metal atoms. The DNA cleavage activity experiment reveals that DNA cleavage promoted by the title complex is lower than that by Na_2MoO_4 which possesses antitumor property, but higher than that by Na_2WO_4.
查看更多>>摘要：A novel flower-like hydrated magnesium carbonate hydroxide, Mg_5 (CO_3)_4(OH)_2 • 4H_2O, with micro-structure composed of individual thin nano-sheets was synthesized using a facile solution route without the use of template or organic surfactant. Reaction time has an important effect on the final morphology of the product. The micro-structure and morphology of Mg_5 (CO__3)_4 ( OH)_2 • 4H_2O were characterized by means of X-ray diffractometry ( XRD) , field-emission scanning electron microscopy( FE-SEM) . Brunauer-Emmett-Teller(BET) surface areas of the samples were also measured. The probable formation mechanism of flower-like micro-structure was discussed. It was found that Mg_5 (CO_3)_4(OH)_2 • 4H_2O with flower-like micro-structure was a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate (DMC) with phenol.
查看更多>>摘要：Single-walled carbon nanotubes ( SWNTs) have a high adsorption ability and nanoscale interactions. Cellulose trisphenylcarbamates possess high enantioseparation ability in high-performance liquid chromatography(HPLC). Single-walled carbon nanotubes mixed with cellulose trisphenylcarbamate are coated on the silica gel as chiral stationary phases and higher enantioseparation factors are obtained. After a single-walled carbon nanotube is linked to the 6-po-sition of cellulose 2,3-bisphenylcarbamate, its enantioseparation resolution increases compared to that of the cellulose trisphenylcarbamate. It is the first time that SWNTs have been applied to enantioseparation. The results indicate that the single-walled carbon nanotubes are good promoters of chiral recognition. This method can be used to improve the enantioseparation efficiency of the polysaccharide chiral stationary phases.
查看更多>>摘要：Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor, this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry ( DESI-MS) , without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer (m/z 841) is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range ( pH = 1—5 ) , and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.
查看更多>>摘要：Metamizole sodium was chosen as a representative of unstable analytes for investigation by discussing the effects of oxygen and solvent on its degradation reaction using the capillary electrophoresis technique. A possible degradation mechanism was deduced from the observed behavior and was confirmed by infra-red spectroscopic study. The degradation reaction could be inhibited obviously by methanol instead of water as the solvent of analyte. Under the optimized conditions; separation voltage of 20 kV, and 5 mmol/L disodium hydrogen phosphate and 5 mmol/L borax with 10% methanol(pH 9. 12) as the running buffer, the standard curve of metamizole sodium was linear in a range of 3. 77— 74. 07 mg/L. A satisfactory result was achieved when the technique was used to detect metamizole sodium in tablet.
查看更多>>摘要：Natural surface coatings collected from natural substances ( NSCsNS) were employed to study the roles of the main chemical components (iron oxides, manganese oxides, and other components) in controlling the adsorption of lead(Pb) and cadmium(Cd) in aquatic environments. The selective chemical extraction followed by the adsorption of Pb and Cd experiments and statistical analysis, were used to investigate the adsorption property of each component. Hydroxylamine hydrochloride was used to remove manganese oxides selectively, and sodium dithionite was used to extract iron oxides and manganese oxides. The result indicated that iron oxides and manganese oxides played an important role in the adsorption of Pb and Cd on NSCsNS, and the relative contribution was about two-thirds. The contribution of manganese oxides was the greatest, with a lesser role indicated for other components. The adsorption ability of manganese oxides for Pb and Cd was greater than that of iron oxides or other components for Pb and Cd. The Pb adsorption observed in each component was greater than Cd adsorption.
查看更多>>摘要：A novel BrΦnsted acidic ionic liquid(IL) based on the cyclic guanidinium cation has been synthesized. This IL, as a strong BrΦnsted acid catalyst or solvent, shows high catalytic activity and biphsaic behavor in the esterifications of carboxylic acids and alcohols. The produced esters as a separate phase can be conveniently decanted out from the IL and the IL is recyclable without any loss of catalytic activity.
查看更多>>摘要：A series of carboxylic acids was esterified to the corresponding esters with TiCl_4 as catalyst at room temperature, in high yields. This catalyst was highly effective for the selective esterification of primary alcohols with carboxylic acids, in the presence of secondary alcohols, and for the selective esterification of saturated acid with alcohol in the presence of conjugated acid or aromatic acid. On account of the high yield, high chemoselectivity, mild condition, and being free of other dehydrants, this is an efficient method.
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