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1.
Corrigendum: Formation and Fragmentation of Protonated Molecules after Ionization of Amino Acid and Lactic Acid Clusters by Collision with Ions in the Gas Phase 下载免费PDF全文
Dr. Jean‐Christophe Poully Dr. Violaine Vizcaino Lucas Schwob Rudy Delaunay Dr. Jaroslav Kocisek Dr. Samuel Eden Prof. Dr. Jean‐Yves Chesnel Dr. Alain Méry Dr. Jimmy Rangama Prof. Dr. Lamri Adoui Dr. Bernd Huber 《Chemphyschem》2016,17(2):325-325
2.
Alessandro De Robertis Antonio Gianguzza Ottavia Giuffr Alberto Pettignano Silvio Sammartano 《应用有机金属化学》2006,20(1):89-98
Quantitative data on the stability of mono‐, di‐ and trimethyltin(IV)‐carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t = 25 °C and I→ 0 mol l?1. Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono‐ > di‐ > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,? O? and? OH groups show a significantly higher stability with respect to analogous ligands with the same number of carboxylic binding sites. The results obtained from all the systems investigated allowed us to formulate the following empirical predictive equation for correlation between complex stability and some simple structural parameters, (1) where ncarb and nOH are the number of carboxylic and alcoholic groups in the ligand, respectively, r is the stoichiometric coefficient of H+ (positive) or OH? (negative) and zcat is the methyltin cation charge (CH3)xSnz+ (z+ = 4 ? x). Distribution diagrams for some representative systems are also reported and are discussed in the light of speciation studies in natural waters. A literature data comparison is made with carboxylate complexes of other metal ions with the same charge as the organotin cations investigated here. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
Two novel dinuclear Ti(IV) complexes of the ligand, 4,4′-methylene-bis (3-hydroxy-2-naphthalene carboxylic acid) (H4L) or pamoic acid having compositions, [(HL)2Ti2(μ-O)(DMF)2]·(DMF)6 (1) and [(L)2Ti2(μ-O)(DMF)2]·(DMF)4(4,4′-Bipy-2H)(H2O), (2) have been synthesized and characterized by analytical and spectral methods and the structure has been established by single crystal XRD. Unlike the reported polymeric structures observed in case of H4L or pamoic acid, the anti-conformation of H4L changes to syn - orientation to avoid poly-metallic complex formation, as noticed in 1 and 2. The dimeric Ti(IV) units stack in the lattice to form helical columns and the space between the adjacent columns is being filled by the solvent molecules in 1 and solvent plus the protonated 4,4′-bipy in the lattice of 2 and thus the neighbor columns are connected through weak interactions. 相似文献
4.
Song Lin ZHANG* Feng Shou TIAN Gong An LI Yu Lu WANG College of Chemistry Environmental Science Henan Normal University Xinxiang 《中国化学快报》2002,13(1)
In recent years, organoselenium compounds have been extensively used as important synthetic reagents and intermediates in organic synthesis1-3. Among them, selenoesters are very useful intermediates in the synthesis of natural compounds4. While there are many methods for the synthesis of selenoesters, the most common approach is the use of selenide anions reacting with acylation reagents. Selenide anions can be obtained by cleavage of diselenides with sodium in liquid ammonia5 or in THF/H… 相似文献
5.
Junying Lai Li‐Qun Wang Kehua Tu Changsheng Zhao Weilin Sun 《Macromolecular rapid communications》2005,26(19):1572-1577
Summary: Copolymers of poly(ethylene oxide) (PEO) and 5,5′‐azodisalicylic acid (Olsalazine, OLZ) were synthesized and evaluated by hydrolysis and in‐vitro biodegradation with azoreductase. It was found that changing the molecular weight of the PEO blocks affected the loading ratio of OLZ, and resulted in significant differences in the hydration and degradability of the copolymers. These novel azo‐containing copolymers can be used in colon‐specific drug delivery.
6.
Hongjuan Jiang Lifen Zhang Xiaowu Jiang Xiaoguang Bao Zhenping Cheng Xiulin Zhu 《Macromolecular rapid communications》2014,35(15):1332-1339
A facile homogeneous polymerization system involving the iniferter agent 1‐cyano‐1‐methylethyl diethyldithiocarbamate (MANDC) and copper(II) acetate (Cu(OAc)2) is successfully developed in bulk using methyl methacylate (MMA) as a model monomer. The detailed polymerization kinetics with different molar ratios (e.g., [MMA]0/[MANDC]0/[Cu(OAc)2]0 = 500/1/x (x = 0.1, 0.2, 0.5, 1.0)) demonstrate that this system has the typical “living”/controlled features of “living” radical polymerization, even with ppm level catalyst Cu(OAc)2, first order polymerization kinetics, a linear increase in molecular weight with monomer conversion and narrow molecular weight distributions for the resultant PMMA. 1H NMR spectra and chain‐extension experiments further confirm the “living” characteristics of this process. A plausible mechanism is discussed.
7.
New thiazole derivatives were synthesized and fully characterized, then coordinated with PtCl4 salt. Also, the newly synthesized Pt(IV) complexes were investigated analytically (elemental and thermogravimetric analyses), spectrally (infrared, UV–visible, mass, 1H NMR, 13C NMR, X‐ray diffraction) as well as theoretically (kinetics, modeling and docking). The data extracted led to the establishment of the best chemical and structural forms. Octahedral geometry was the only formula proposed for all complexes, which is favorable for d6 systems. The molecular ion peaks from mass spectral analysis coincide with all analytical data, confirming the molecular formula proposed. X‐ray diffraction (XRD) and scanning electron microscopy (SEM) allowed discrimination of features between crystalline particles and other amorphous morphology. By applying Gaussian09 as well as HyperChem 8.2 programs, the best structural forms were obtained, as well as computed significant parameters. Computed parameters such as softness, hardness, surface area and reactivity led us towards application in two opposing pathways: tumor inhibition and oxidation activation. The catalytic oxidation for CO was conducted over PtO2, which was yielded from calcination of the most reactive complex. The success of catalytic role for synthesized PtO2 was due to its particulate size and surface morphology, which were estimated from XRD patterns and SEM images, respectively. The antitumor activity was tested versus HCT‐116 and HepG‐2 cell lines. Mild toxicity was recorded for two of the derivatives and their corresponding complexes. This degree of toxicity is more favorable in most cases, due to exclusion of serious side effects, which is coherently attached with known antitumor drugs. 相似文献
8.
Oxo‐vanadium(IV) Schiff base complex supported on modified MCM‐41: a reusable and efficient catalyst for the oxidation of sulfides and oxidative S–S coupling of thiols 下载免费PDF全文
Oxo‐vanadium(IV) Schiff base complex supported on MCM‐41 as an organic–inorganic hybrid heterogeneous catalyst was synthesized with post‐grafting of MCM‐41 with 3‐aminoropropyltrimethoxysilane and subsequent reaction with 3,4‐dihydroxybenzaldehyde and then complexation with oxo‐vanadium acetylacetonate salt. The catalyst was analysed using a series of characterization techniques such as Fourier transform infrared spectroscopy, small‐angle X‐ray diffraction, nitrogen absorption isotherm, transmission electron microscopy and thermogravimetric analysis. The data collected provided evidence that the vanadium complex was anchored onto MCM‐41. High catalytic activity of this catalyst was observed in the oxidation of various sulfides and thiols (into sulfoxides and disulfides, respectively) with urea hydrogen peroxide as oxidant in high to excellent yields and selectivity under mild conditions. The heterogeneous catalyst could be recovered easily and reused several times without significant loss in catalytic activity and selectivity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
Taichi Nakano Takashi Miyamoto Takanori Endoh Makoto Shimotani Naoki Ashida Toshishige Morioka Yutaka Takahashi 《应用有机金属化学》2004,18(2):65-67
The palladium‐catalyzed silastannation of acetylenes with tributyl(trimethylsilyl)stannane in the presence of triethylphosphite is reported for the first time. The reaction occurs at room temperature to give (Z)‐silyl(stannyl)ethenes in high yields. The protodemetallation of the resulting adducts with HCl–tetraethylammonium chloride is described first, which demonstrates that the reaction is governed only by the stability of a carbonium ion arising from the protonation to (Z)‐silyl(stannyl)ethenes rather than the hard and soft acid and base principle, i.e. the β‐cation stabilization effect (σ–π stabilization one) of a stannyl group in the carbonium ion is rather significant. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
Rosenani A. Haque Abbas Washeel Salman Srinivasa Budagumpi Amirul Al‐Ashraf Abdullah Zena A. Abdul Hameed Al‐Mudaris Amin M. S. Abdul Majid 《应用有机金属化学》2013,27(8):465-473
A series of Ag(I) complexes ( 6 , 7 , 8 , 9 ) derived from imidazol‐2‐ylidenes was synthesized by reacting Ag2O with an o‐, m‐, p‐xylyl or 1,3,5‐triazine‐linked imidazolium salts ( 1 , 2 , 3 , 4 ) and then characterizing these using various spectro‐analytical techniques. Additionally, triazine‐linked bis‐imidazolium salt 5 was characterized using the single‐crystal X‐ray diffraction method. Complexes 6–9 were formed from the N‐heterocyclic carbene ligand precursors 1–3 as PF6‐ salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6–9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram‐negative and Gram‐positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5‐fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC50 value of 3.4 μm , whereas the lowest was observed for complex 9 with an IC50 value of 18.1 μm . Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
11.
Xuran Li Simiao Chen Jinghui Zhang Li Yu Weiyan Chen Yuyan Zhang 《Molecules (Basel, Switzerland)》2022,27(10)
Dried roots of Polygala tenuifolia (YuanZhi in Chinese) are widely used in Chinese herbal medicine. These components in YuanZhi have significant anti-oxidation properties owing to high levels of 3,6’-disinapoylsucrose (DISS) and Polygalaxanthone III (PolyIII). In order to efficiently extract natural medicines, response surface methodology (RSM) and least squares support vector machine (LSSVM) were used for the modeling and optimization of ultrasound-assisted extraction of DISS and PolyIII together to determine the antioxidant activity of the extracts obtained from YuanZhi. For the optimal combination of the comprehensive yield of DISS and PolyIII (Y), the Box-Behnken design (BBD) was used to improve extraction time (X1), extraction temperature (X2), liquid–solid ratio (X3), and ethanol concentration (X4). The optimal process parameters were determined to be as follows: extraction time, 93 min; liquid–solid ratio, 40 mL/g; extraction temperature, 48 °C; and ethanol concentration, 67%. With these conditions, the predictive optimal combination comprehensive evaluation value is 13.0217. It was clear that the LS-SVM model had higher accuracy in predictive and optimization capabilities, with higher antioxidant activity and lower relative deviations values, than did RSM. Hence, the LS-SVM model proved to be more effective for the analysis and improvement of the extraction process. 相似文献
12.
13.
Neha Gupta Saurav Kumar Choudhary Neeta Bhagat Muthusamy Karthikeyan Archana Chaturvedi 《Molecules (Basel, Switzerland)》2021,26(14)
The binding of heat stable enterotoxin (STa) secreted by enterotoxigenic Escherichia coli (ETEC) to the extracellular domain of guanylyl cyclase c (ECDGC-C) causes activation of a signaling cascade, which ultimately results in watery diarrhea. We carried out this study with the objective of finding ligands that would interfere with the binding of STa on ECDGC-C. With this view in mind, we tested the biological activity of a alkaloid rich fraction of Holarrhena pubescens against ETEC under in vitro conditions. Since this fraction showed significant antibacterial activity against ETEC, we decided to test the screen binding affinity of nine compounds of steroidal alkaloid type from Holarrhena pubescens against extracellular domain (ECD) by molecular docking and identified three compounds with significant binding energy. Molecular dynamics simulations were performed for all the three lead compounds to establish the stability of their interaction with the target protein. Pharmacokinetics and toxicity profiling of these leads demonstrated that they possessed good drug-like properties. Furthermore, the ability of these leads to inhibit the binding of STa to ECD was evaluated. This was first done by identifying amino acid residues of ECDGC-C binding to STa by protein–protein docking. The results were matched with our molecular docking results. We report here that holadysenterine, one of the lead compounds that showed a strong affinity for the amino acid residues on ECDGC-C, also binds to STa. This suggests that holadysenterine has the potential to inhibit binding of STa on ECD and can be considered for future study, involving its validation through in vitro assays and animal model studies. 相似文献
14.
Nanomagnetic‐supported Sulfonic Acid: Simple and Rapid Method for the Synthesis of α,α′‐Bis‐(substituted‐benzylidene) Cycloalkanones 下载免费PDF全文
Nanomagnetic‐supported sulfonic acid is found to be a powerful and reusable heterogeneous catalyst for the rapid synthesis of α,α′‐bis‐(substituted‐benzylidene)cycloalkanones under conventional heating and solvent free conditions. High yield, simple work up and easy recovery of the catalyst are the most obvious advantages of this procedure. 相似文献
15.
Hans-Detlev Gilsing Jürgen Angerer Dietrich Prescher 《Monatshefte für Chemie / Chemical Monthly》2002,133(8):1147-1155
Summary. The synthesis of two oxidized metabolites of bis-(2-ethylhexyl)-phthalate is described. The target structures were obtained
by esterification of the appropriate alcohol carrying a protected hydroxy group with phthalic anhydride, followed by deprotection
and further oxidation.
Received February 26, 2002. Accepted March 6, 2002 相似文献
16.
Günter Grampp Stephan Landgraf Tomasz Wesierski Beata Jankowska Ewa Kalisz Dana-Maria Sabou Boryana Mladenova 《Monatshefte für Chemie / Chemical Monthly》2002,133(10):1363-1372
Summary. The kinetics of the CrO(O2)2 formation by H2O2 and Cr2O7
2− in aqueous acidic media was measured at 293 ± 2 K in a pH range between 2.5 and 3.3. Using the stopped-flow method with rapid scan UV-VIS detection, the rate law of the formation
of CrO(O2)2 was determined. For the media HClO4, HNO3 and CH3COOH, the reaction order in the Cr2O7
2− concentration was found to be 0.5. For [H2O2] as well as for [H+], the reaction was first order in all acids used. In HCl and H2SO4 media the reaction was first order in Cr2O7
2−. At T = 293 ± 2 K the rate constant for the formation of Cr(O)(O2)2 was found to be (7.3 ± 1.9) · 102 M−3/2 s−1 in HClO4.
Corresponding author. E-mail: grampp@ptc.tu-graz.ac.at
Received January 30, 2002; accepted (revised) June 5, 2002 相似文献
17.
A kinetic method is presented for the determination of Cu(II) in water. It is based on the catalytic effect of Cu(II) on
the oxidation of mercaptosuccinic acid by chromate in acidic media. The extent of the reaction is followed spectrophotometrically
at 345 nm and pseudo-first order rate coefficients are determined as a function of catalyst concentration. The optimum operating
conditions regarding ionic strength, temperature and concentration of reagents were established. Interference by several ionic
species was studied and the effects of Fe(III) and Pb(II) were suppressed by complexation with pyrophosphate. Calibration
lines were obtained for both low (30–640 μg · l−1) and high (640–1500 μg · l−1) catalyst concentrations. The relative standard deviation for 625 μg · l−1 Cu(II) is 6.1% (n = 5). The detection limit is 22 μg · l−1. The method was applied to real samples of river water of the mining region of Baia-Mare, Northern Romania. The results were
compared to those obtained by an officially standardized AAS method. Good agreement was attained. The method is inexpensive,
fairly rapid and sensitive. Moreover, its working range covers the exact range of concentrations usually encountered in the
mentioned geographic area.
Received July 28, 2000; accepted December 10, 2001; published online June 24, 2002 相似文献
18.
Mara Gutirrez-Snchez Aurelio Romero-Castro Jos Correa-Basurto Martha Cecilia Rosales-Hernndez Itzia Irene Padilla-Martínez Jessica Elena Mendieta-Wejebe 《Molecules (Basel, Switzerland)》2021,26(22)
Compound 5-{[(2E)-3-bromo-3-carboxyprop-2-enoyl]amino}-2-hydroxybenzoic acid (C1), a new 5-aminosalicylic acid (5-ASA) derivative, has proven to be an antioxidant in vitro and an anti-inflammatory agent in mice. The in vivo inhibition of myeloperoxidase was comparable to that of indomethacin. The aim of this study was to take another step in the preclinical evaluation of C1 by examining acute toxicity with the up-and-down OECD method and pharmacokinetic profiles by administration of the compound to Wistar rats through intravenous (i.v.), oral (p.o.), and intraperitoneal (i.p.) routes. According to the Globally Harmonized System, C1 belongs to categories 4 and 5 for the i.p. and p.o. routes, respectively. An RP-HPLC method for C1 quantification in plasma was successfully validated. Regarding the pharmacokinetic profile, the elimination half-life was approximately 0.9 h with a clearance of 24 mL/min after i.v. administration of C1 (50 mg/kg). After p.o. administration (50 mg/kg), the maximum plasma concentration was reached at 33 min, the oral bioavailability was about 77%, and the compound was amply distributed to all tissues evaluated. Therefore, C1 administered p.o. in rats is suitable for reaching the colon where it can exert its effect, suggesting an important advantage over 5-ASA and indomethacin in treating ulcerative colitis and Crohn’s disease. 相似文献
19.
Krecar D Rosner M Draxler M Bauer P Hutter H 《Analytical and bioanalytical chemistry》2006,384(2):525-530
The germanium concentration and the position and thickness of the quantum well in molecular beam epitaxy (MBE)-grown SiGe
were quantitatively analyzed via low-energy Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS). In
these samples, the concentrations of Si and Ge were assumed to be constant, except for the quantum well, where the germanium
concentration was lower. The thickness of the analyzed quantum well was about 12 nm and it was situated at a depth of about
60 nm below the surface. A dip showed up in the RBS spectra due to the lower germanium concentration in the quantum well,
and this was evaluated. Good depth resolution was required in order to obtain quantitative results, and this was obtained
by choosing a primary energy of 500 keV and a tilt angle of 51° with respect to the surface normal. Quantitative information
was deduced from the raw data by comparing it with SIMNRA simulated spectra. The SIMS measurements were performed with oxygen
primary ions. Given the response function of the SIMS instrument (the SIMS depth profile of the germanium delta (δ) layer),
and using the forward convolution (point-to-point convolution) model, it is possible to determine the germanium concentration
and the thickness of the analyzed quantum well from the raw SIMS data. The aim of this work was to compare the results obtained
via RBS and SIMS and to show their potential for use in the semiconductor and microelectronics industry. The detection of
trace elements (here the doping element antimony) that could not be evaluated with RBS in low-energy mode is also demonstrated
using SIMS instead. 相似文献
20.
Melamine trisulfunic acid is employed as a recyclable catalyst for the condensation reaction of aromatic aldehydes with 3‐methyl‐l‐phenyl‐2‐pyrazolin‐5‐one. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4′‐(arylmethylene)‐bis‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ols) in 80‐96% yields. 相似文献