共查询到20条相似文献,搜索用时 31 毫秒
1.
Background
The 85-kDa cytosolic phospholipase A2 (cPLA2) mediates arachidonic acid (AA) release in MDCK cells. Although calcium and mitogen-activated protein kinases regulate cPLA2, the correlation of cPLA2 translocation and phosphorylation with MAPK activation and AA release is unclear. 相似文献2.
Cai-Hong Zhan Xiao-Juan Wang Zhan-Guo Jiang Ling-Xian Chen Yun-Long Feng 《Structural chemistry》2010,21(6):1195-1201
Abstract
p-Thioacetatebenzoic acid (H2L) and a combination of N-donor ligand of 4,4′-bipyridine (4,4′-bipy) with metal(II) ions give rise to three 3D supramolecules of general formula [M(HL)2(4,4′-bipy)2(H2O)2] · H2O, M = CoII (1), ZnII (2), NiII (3), which were characterized by crystallographic methods. The crystals are isostructural and belong to the triclinic P[`1] P\bar{1} space group. The structure can be considered to construct from 1D chains and further linked by hydrogen bonds into the final 3D supramolecular networks. The electrochemical behavior of complexes 1 and 3 were studied by cyclic voltammetry, indicating that the electron transfers in the electrode reaction are irreversible. Meanwhile, complex 2 exhibits significantly red-shifted emission in solid state at room temperature. 相似文献3.
Hai-Jun Dong Min Wang Shu-Wei Huang Yan-Ling Wu Hao-Hong Li Zhi-Rong Chen 《Journal of Cluster Science》2010,21(4):825-835
Abstract
The hydrothermal reaction of Gd(NO3)3·6H2O with 2,2′-bipyridyl-4,4′-dicarboxylic acid(H2BPDC) ligand results in the formation of a new Gd(III) polymer: {[Gd2(BPDC)3(H2O)3]·H2O} n..(1). The central gadolinium ion is coordinated by eight oxygen atoms to give a dicapped triangular prism geometry. Based on the versatile coordination modes of BPDC2− ligand, together with hydrogen bonds and π···π stacking interactions, a 3-D network is presented. DFT calculation was executed to probe the electronic structure of 1. 相似文献4.
Abstract
Arylaminotetrazoles were efficiently synthesized from secondary arylcyanamides by application of ZnCl2/AlCl3/silica as a reusable heterogeneous Lewis acid catalyst. 5-Arylamino-1H-tetrazoles can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while with electron-releasing groups 1-aryl-5-amino-1H-tetrazoles will be produced. The former isomer is also produced within longer reaction times (~20 h) even with electron-releasing groups. 相似文献5.
Ranjan K. Bhatt Satyasheel Sharma Mahendra Nath 《Monatshefte für Chemie / Chemical Monthly》2012,54(1):309-316
Abstract
An improved synthetic procedure is developed for the regioselective nitration of a phenyl group of meso-tetraphenylporphyrin by using NaNO2 in a mixture of trichloroacetic acid and AcOH. The meso-(4-nitrophenyl)porphyrins are successfully reduced to corresponding meso-(4-aminophenyl)porphyrins by SnCl2 under acidic conditions. In addition, an efficient one-pot methodology for synthesizing a series of novel meso-substituted porphyrinic thiazolidinone conjugates is developed by reacting meso-(4-aminophenyl)porphyrins with various aromatic aldehydes and mercaptoacetic acid in refluxing toluene using La(OTf)3 as a catalyst. The products obtained are characterized on the basis of their spectral data. Preliminary photophysical properties of the newly synthesized compounds are reported. 相似文献6.
Abstract
Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone (H2L) have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, electronic and EPR spectra. The oxovanadium(V) complex [VOL(OCH3)] is crystallized in two polymorphic forms, denoted by 1a and 1b, with space groups Pn21a and P[`1] P_{{\bar{1}}} , respectively. Both have distorted square pyramidal structures. 相似文献7.
Viet-Laï Pham Marie-Sandrine Cadel Cécile Gouzy-Darmon Chantal Hanquez Margery C Beinfeld Pierre Nicolas Catherine Etchebest Thierry Foulon 《BMC biochemistry》2007,8(1):21
Background
Aminopeptidase B (Ap-B; EC 3.4.11.6) catalyzes the cleavage of basic residues at the N-terminus of peptides and processes glucagon into miniglucagon. The enzyme exhibits, in vitro, a residual ability to hydrolyze leukotriene A4 into the pro-inflammatory lipid mediator leukotriene B4. The potential bi-functional nature of Ap-B is supported by close structural relationships with LTA4 hydrolase (LTA4H ; EC 3.3.2.6). A structure-function analysis is necessary for the detailed understanding of the enzymatic mechanisms of Ap-B and to design inhibitors, which could be used to determine the complete in vivo functions of the enzyme. 相似文献8.
Jian-Ling Wang Ke-Ling Hou Feng-Ying Bai Yong-Heng Xing Zhan Shi 《Structural chemistry》2012,23(1):275-285
Abstract
By using 1,4-benzene-dicarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid as mixed-linkers, three novel 3D lanthanide coordination polymers, [Ln(BDC)0.5(BTEC)0.5(H2O)] (Ln = Eu (1) and Gd (2)) and [Tb(BDC)0.5(BTEC)0.5(H2O)] (3) (H2BDC = 1,4-benzene-dicarboxylic acid, H4BTEC = 1,2,4,5-benzenetetracarboxylic acid) were synthesized via hydrothermal reaction. The X-ray single crystal analyses reveal that the three coordination polymers present two types of different crystal cell parameters and hereby exhibited two kinds of different metal–organic frameworks, although they have the similar chemical formula [Ln(BDC)0.5(BTEC)0.5(H2O)]. Of these complexes, complexes 1 and 2 are isomorphous, crystallizing in monoclinic, space group P21/n. While 3 is a 3D eight-coordinated terbium complex with triclinic crystal system and P-1 space group. The occurrence of the different structures of these complexes under the similar preparation method may be related to the lanthanide contraction effect. Additional, the thermogravimetric analyses and photoluminescent properties for complexes 1 and 3 were discussed in detail. 相似文献9.
Abstract
Tris(2-ureidobenzyl)amines bearing three differentially substituted arms have been synthesized. They possess an asymmetric nitrogen atom, the pivotal one, and thus they feature C 1 symmetry. The self-assembly of these C 1-symmetric tris(2-ureidobenzyl)amines may potentially lead to multiple regio- and diastereoisomeric capsules coming from the pairing of the four stereoisomeric monomers with configurations (R, P), (S, P), (R, M) and (S, M). The 1H- and 19F{1H}-NMR spectra confirm the presence of dimeric aggregates, as a mixture of several regio- and diastereoisomeric species. 相似文献10.
Madharam Sudershan Rao Bhupender S. Chhikara Rakesh Tiwari Amir N. Shirazi Keykavous Parang Anil Kumar 《Monatshefte für Chemie / Chemical Monthly》2012,38(2):263-268
Abstract
Synthesis of 12-aryl-8,9,10,12-tetrahydro-benzo[a]xanthen-11-ones was achieved by one-pot condensation of β-naphthol, substituted benzaldehydes, and 1,3-dicarbonyl compounds catalyzed by Sc(OTf)3 under microwave irradiation in excellent isolated yields. The catalyst was recycled up to four cycles with no appreciable loss in catalytic activity. The compounds were evaluated for Src kinase activity and anticancer activity. 相似文献11.
Issa Yavari Nasir Iravani S. Zahra Sayyed-Alangi Rahimeh Hajinasiri 《Monatshefte für Chemie / Chemical Monthly》2009,35(1):1199-1204
Abstract
An efficient synthesis of alkyl acylcarbamodithioates by reaction of acid chlorides with ammonium thiocyanate in the presence of thiols is described. The unusually large values of 5 J FH = 12–15 Hz, observed for alkyl (2-fluorobenzoyl)carbamodithioates provide information about Ar–C–N–H torsion in these compounds. 相似文献12.
The present work presents an alternative approach to ethanol production from sweet sorghum: without detoxification, acid-impregnated
fresh sweet sorghum stem which contains soluble (glucose and sucrose) and insoluble carbohydrates (cellulose and hemicellulose)
was steam pretreated under mild temperature of 100 °C. Simultaneous saccharification and fermentation experiments were performed
on the pretreated slurries using Saccharomyces cerevisiae. Experimentally, ground fresh sweet sorghum stem was combined with H2SO3 at dosages of 0.25, 0.50, and 0.75 g/g dry matter (DM) and steam pretreated by varying the residence time (60, 120, or 240 min).
According to enzymatic hydrolysis results and ethanol yields, H2SO3 was a powerful and mild acid for improving enzymatic digestibility of sorghum stem. At a solid loading of 10% (w/v) and acid dosage of 0.25 g/g DM H2SO3 at 100 °C for 120 min, 44.5 g/L ethanol was obtained after 48 ± 4 h of simultaneous saccharification and fermentation. This
corresponded to an overall ethanol yield of 110% of the theoretical one, based on the soluble carbohydrates in the fresh sweet
sorghum stem. The concentrations of hydroxymethylfurfural and furfural of the sulfurous acid pretreated samples were below
0.4 g/L. Ethanol would not inhibit the cellulase activity, at least under the concentration of 34 g/L. 相似文献
13.
S. X. Xiao J. J. Zhang X. Li L. J. Ye H. W. Gu N. Ren 《Journal of Thermal Analysis and Calorimetry》2010,102(2):813-817
A ternary binuclear complex of dysprosium chloride hexahydrate with m-nitrobenzoic acid and 1,10-phenanthroline, [Dy(m-NBA)3phen]2·4H2O (m-NBA: m-nitrobenzoate; phen: 1,10-phenanthroline) was synthesized. The dissolution enthalpies of [2phen·H2O(s)], [6m-HNBA(s)], [2DyCl3·6H2O(s)], and [Dy(m-NBA)3phen]2·4H2O(s) in the calorimetric solvent (VDMSO:VMeOH = 3:2) were determined by the solution–reaction isoperibol calorimeter at 298.15 K to be
\Updelta\texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2phen·H2O(s), 298.15 K] = 21.7367 ± 0.3150 kJ·mol−1,
\Updelta\texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [6m-HNBA(s), 298.15 K] = 15.3635 ± 0.2235 kJ·mol−1,
\Updelta\texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2DyCl3·6H2O(s), 298.15 K] = −203.5331 ± 0.2200 kJ·mol−1, and
\Updelta\texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [[Dy(m-NBA)3phen]2·4H2O(s), 298.15 K] = 53.5965 ± 0.2367 kJ·mol−1, respectively. The enthalpy change of the reaction was determined to be
\Updelta\textr H\textmq = 3 6 9. 4 9 ±0. 5 6 \textkJ·\textmol - 1 . \Updelta_{\text{r}} H_{\text{m}}^{\theta } = 3 6 9. 4 9 \pm 0. 5 6 \;{\text{kJ}}\cdot {\text{mol}}^{ - 1} . According to the above results and the relevant data in the literature, through Hess’ law, the standard molar enthalpy of
formation of [Dy(m-NBA)3phen]2·4H2O(s) was estimated to be
\Updelta\textf H\textmq \Updelta_{\text{f}} H_{\text{m}}^{\theta } [[Dy(m-NBA)3phen]2·4H2O(s), 298.15 K] = −5525 ± 6 kJ·mol−1. 相似文献
14.
Abstract
Gallium complexes of l-glutamine have been studied polarographically in aqueous media. The reduction was found to be irreversible and diffusion controlled in the presence of 0.1 M KNO3 and 0.002% Triton-x-100. The values of kinetic parameters, transfer coefficient (α n), and formal rate constant ( k\textf,\texth0 k_{{{\text{f}},{\text{h}}}}^{0} ) of the electrode reactions were calculated by Koutecky's method. The stability constants and composition of the gallium(III)-l-glutamine complexes were evaluated with the help of the Deford-Hume method. The values of stability constants of 1:1, 1:2, and 1:3 gallium(III)-l-glutamine complexes are 1.35, 6.5, and 1,350 at 30 °C, respectively. The values of thermodynamic parameters, the free energy of activation, the enthalpy of activation, and the entropy of activation have been determined at 30 °C. The formation of the metal complexes has been found to be non-spontaneous, endothermic in nature, and entropically favorable at higher temperature. 相似文献15.
Eva Rosberg-Cody Alena Liavonchanka Cornelia Göbel R Paul Ross Orla O'Sullivan Gerald F Fitzgerald Ivo Feussner Catherine Stanton 《BMC biochemistry》2011,12(1):9
Background
The aim of this study was to determine the catalytic activity and physiological role of myosin-cross-reactive antigen (MCRA) from Bifidobacterium breve NCIMB 702258. MCRA from B. breve NCIMB 702258 was cloned, sequenced and expressed in heterologous hosts (Lactococcus and Corynebacterium) and the recombinant proteins assessed for enzymatic activity against fatty acid substrates. 相似文献16.
Abstract
Direct reductive amination of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde and 3-(4-methylphenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde with various substituted aromatic amines using NaBH4 in the presence of I2 as reducing agent is described. The reaction has been carried out in anhydrous methanol under neutral conditions at room temperature. The structure of newly synthesized diphenyl pyrazolylmethylanilines was established on the basis of IR, 1H, 13C NMR, and mass spectral data. All diphenyl pyrazolylmethylaniline derivatives were tested in vitro for their antifungal and antibacterial activity against different strains of fungi and bacteria. Most of the compound exhibited considerable antifungal activity but poor antibacterial activity against the test strains. 相似文献17.
Jian-zhang Li Xi-yang He Jun Zeng Zheng-hua Xiao Sheng-ying Qin 《Transition Metal Chemistry》2012,37(1):31-35
Abstract
Mono-Schiff base Mn(III) complexes of general formula MnL2Cl, with pendant aza-crown or morpholino substituents, have been synthesized and investigated as catalysts for the epoxidation of styrene at ambient temperature and pressure. The highest conversion yield of styrene and selectivity for epoxide were 40 and 96%, respectively. These complexes have been also studied as catalysts for the aerobic oxidation of p-xylene to p-toluic acid. The effects of the crown ether group on the catalytic properties of the complexes are discussed. The oxidation of p-xylene to p-toluic acid with air at 120 °C under normal pressure proceeded efficiently in the presence of the aza-crown ether substituted complexes. Significant selectivity for p-toluic acid (up to ~87%) and conversion of p-xylene (up to ~30%) were obtained. 相似文献18.
J. Thanusu V. Kanagarajan M. Gopalakrishnan 《Research on Chemical Intermediates》2010,36(9):1073-1084
Abstract
A series of bis heterocycles comprising both piperidine and thiohydantoin nuclei namely 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones is synthesized and characterized by melting point, elemental analysis, MS, FT–IR, one-dimensional NMR (1H, D2O exchanged 1H and 13C), two-dimensional HOMOCOSY, and NOESY spectroscopic data. 相似文献19.
Jaroslav Kříž Jiří Dybal Emanuel Makrlík Jan Budka Petr Vaňura 《Monatshefte für Chemie / Chemical Monthly》2010,287(1):19-22
Abstract
Using 1H NMR spectroscopy together with density functional theoretical calculations, it is shown that electroneutral p-tert-butylcalix[4]arenetetraacetic acid forms an equimolar complex with a proton in the form of the H3O+ ion in nitrobenzene-d 5. Protons were offered by hydrogen bis(1,2-dicarbollyl)cobaltate and converted to hydroxonium ions by traces of water. In the resulting complex, the H3O+ cation is bound by strong hydrogen bonds to two phenoxy oxygen atoms of the parent calix[4]arene ligand and to one carbonyl oxygen of the corresponding COOH group of this ligand. 相似文献20.
Nina I. Giricheva Georgiy V. Girichev Yulia S. Medvedeva Sergey N. Ivanov Anna V. Bardina Vyacheslav M. Petrov 《Structural chemistry》2011,22(2):373-383
A combined gas-phase electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pvtz, MP2/cc-pvtz) study of molecular
structure of 2-nitrobenzenesulfonamide (2-NBSA) was carried out. Quantum chemical calculations showed that 2-NBSA has four
conformers, two of which are stabilized by intramolecular hydrogen bond. The latter (with the S–N bond in a close to orthogonal
position around the phenyl ring and differing from each other by staggered or eclipsed positions of the N–H and S=O bonds
in the SO2NH2 group) presented in a saturated vapor over 2-NBSA at T = 433 (3) K in commensurable amounts. Experimental internuclear distances (Ǻ) for the staggered conformer are (?): r
h1(C–H)av. = 1.071(9), r
h1(C–C)av. = 1.390(4), r
h1(C–S) = 1.789(8), r
h1(S=O)av. = 1.427(6), r
h1(S–N) = 1.644(6), r
h1(N–O)av. = 1.221(4), r
h1(C′–N) = 1.487(8), r
h1(N–H)av. = 1.014. Calculations at B3LYP/cc-pvtz level were performed to determine the structure and the energies of the transition
states between conformers. It was shown that the conformer structures of free molecule differ from those of a molecule stabilized
by intermolecular hydrogen bonds in a crystal. Influence of a substituent X (X = –CH3, –NO2) on conformational features of the ortho-substituted benzenesulfonamide was established. 相似文献