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91.
Abolghasem Davoodnia Sadegh Allameh Samineh Fazli Niloofar Tavakoli-Hoseini 《Chemical Papers》2011,65(5):714-720
A convenient method for the synthesis of tetrahydrobenzo[b]pyrans by a one-pot three-component cyclocondensation of dimedone, aryl aldehydes, and malononitrile in water using silica
gel-supported polyphosphoric acid (PPA-SiO2) as an efficient and reusable catalyst is described. The present methodology offers several advantages, such as a simple
procedure with ease of handling, short reaction time, high yields, and the absence of any volatile and hazardous organic solvents. 相似文献
92.
Davoodnia Abolghasem Heravi Majid M. Rezaei-Daghigh Leila Tavakoli-Hoseini Niloofar 《中国化学》2010,28(3):429-433
A green and improved method for the synthesis of β‐amido ketones through one‐pot multi‐component reaction of an enolizable ketone, aryl aldehyde, acetonitrile or benzonitrile in the presence of trimethylsilyl chloride using 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [(CH2)4SO3HMIM][HSO4], a Br?nsted‐acidic ionic liquid, as an effective and recyclable catalyst is described. The present methodology offers several advantages such as simple procedure with an easy work‐up, relatively short reaction time, and good to excellent yields. 相似文献
93.
The creation of monolithically integratable sources of single and entangled photons is a top research priority with formidable challenges: The production, manipulation, and measurement of the photons should all occur in the same material platform, thereby fostering stability and scalability. Here we demonstrate efficient photon pair production in a semiconductor platform, gallium arsenide. Our results show type-I spontaneous parametric down-conversion of laser light from a 2.2 mm long Bragg-reflection waveguide, and we estimate its internal pair production efficiency to be 2.0×10(-8) (pairs/pump photon). This is the first time that significant pair production has been demonstrated in a structure that can be electrically self-pumped and which can form the basis for passive optical circuitry, bringing us markedly closer to complete integration of quantum optical technologies. 相似文献
94.
Quantitative structure property relationships were proposed to calculate the binary interaction terms of the Jouyban-Acree model using coefficients of Abraham solvational models. The applicability of the proposed methods for reproducing solubility data of anthracene in binary solvents has been evaluated using 56 solubility data sets collected from the literature. The mean percentage deviation (MPD) of experimental and calculated solubilities, using predicted mole fraction solubility of anthracene in solvents 1 and 2, has been computed as a measure of accuracy and the MPD of the proposed methods were 5.5 and 4.2%. The accuracy of the method was compared with that of a previously reported method where the MPD was 14.4% and the mean differences between proposed and previous methods was statistically significant. To provide a predictive model, solubility of anthracene was computed using Abraham solvational models and employed to predict the solubility in binary solvents using derived model constants of Jouyban-Acree model and the obtained MPDs were 37.9 and 22.2%, respectively. 相似文献
95.
Haniyeh Fayazfar Abdollah Afshar Abolghasem Dolati 《Applied biochemistry and biotechnology》2014,173(6):1511-1528
Carbon nanotube/nanoparticle hybrid materials have been proven to exhibit high electrocatalytic activity suggesting broad potential applications in the field of electroanalysis. For the first time, modification of Ta electrode with aligned multi-walled carbon nanotubes/Au nanoparticles introduced for the sensitive determination of the antibiotic drug, cefazolin (CFZ). The electrochemical response characteristics of the modified electrode toward CFZ were investigated by means of cyclic and linear sweep voltammetry. The modified electrode showed an efficient catalytic activity for the reduction of CFZ, leading to a remarkable decrease in reduction overpotential and a significant increase of peak current. Under optimum conditions, the highly sensitive modified electrode showed a wide linear range from 50 pM to 50 μM with a sufficiently low detection limit of 1?±?0.01 pM (S/N?=?3). The results indicated that the prepared electrode presents suitable characteristics in terms of sensitivity (458.2?±?2.6 μAcm?2/μM), accuracy, repeatability (RSD of 1.8 %), reproducibility (RSD of 2.9 %), stability (14 days), and good catalytic activity in physiological conditions. The method was successfully applied for accurate determination of trace amounts of CFZ in pharmaceutical and clinical preparations without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis. 相似文献
96.
Majid M. Heravi Mina Saeedi Narges Karimi Masumeh Zakeri Yahya S. Beheshtiha Abolghasem Davoodnia 《合成通讯》2013,43(4):523-529
1-(4-Sulfonic acid)butyl-3-methylimidazolium hydrogen sulfate ([(CH2)4SO3HMIM][HSO4]) efficiently catalyzed a four-component Hantzsch reaction of aldehyde, ethylacetoacetate, dimedone, and ammonium acetate to afford the corresponding polyhydroquinoline derivatives. 相似文献
97.
Convenient and regioselective synthesis of indolizine and pyrrolo[2,1-a]isoquinoline/quinoline derivatives by one-pot multicomponent reaction of N-substituted pyridinium and isoquinolinum/quinolinium salts with alkyl propiolates in the presence triphenylphosphine is described. 相似文献
98.
Valiallah Hosseininasab Alison C. McQuilken Abolghasem Bakhoda Jeffery A. Bertke Qadir K. Timerghazin Timothy H. Warren 《Angewandte Chemie (International ed. in English)》2020,59(27):10854-10858
S‐Nitrosothiols (RSNOs) serve as air‐stable reservoirs for nitric oxide in biology. While copper enzymes promote NO release from RSNOs by serving as Lewis acids for intramolecular electron‐transfer, redox‐innocent Lewis acids separate these two functions to reveal the effect of coordination on structure and reactivity. The synthetic Lewis acid B(C6F5)3 coordinates to the RSNO oxygen atom, leading to profound changes in the RSNO electronic structure and reactivity. Although RSNOs possess relatively negative reduction potentials, B(C6F5)3 coordination increases their reduction potential by over 1 V into the physiologically accessible +0.1 V vs. NHE. Outer‐sphere chemical reduction gives the Lewis acid stabilized hyponitrite dianion trans‐[LA‐O‐N=N‐O‐LA]2? [LA=B(C6F5)3], which releases N2O upon acidification. Mechanistic and computational studies support initial reduction to the [RSNO‐B(C6F5)3] radical anion, which is susceptible to N?N coupling prior to loss of RSSR. 相似文献
99.
100.
A simple modified TiO(2) nanotubes electrode was fabricated by electrodeposition of Pd, Pt and Au nanoparticles. The TiO(2) nanotubes electrode was prepared using the anodizing method, followed by modifying Pd nanoparticles onto the tubes surface, offering a uniform conductive surface for electrodeposition of Pt and Au. The performance of the modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The Au/Pt/Pd/TiO(2) NTs modified electrode represented a high sensitivity towards individual detection of dopamine as well as simultaneous detection of dopamine and uric acid using 0.1 M phosphate buffer solution (pH 7.00) as the base solution. In both case, electro-oxidation peak currents of dopamine were linearly related to accumulated concentration over a wide concentration range of 5.0 × 10(-8) to 3.0 × 10(-5) M. However in the same range of dopamine concentration, the sensitivity had a significant loss at Pt/Pd/TiO(2) NTs electrode, suggesting the necessity for Au nanoparticles in modified electrode. The limit of the detection was determined as 3 × 10(-8) M for dopamine at signal-to-noise ratio equal to 3. Furthermore, the Au/Pt/Pd/TiO(2) NTs modified electrode was able to distinguish the oxidation response of dopamine, uric acid and ascorbic acid in mixture solution of different acidity. It was shown that the modified electrode possessed a very good reproducibility and long-term stability. The method was also successfully applied for determination of DA in human urine samples with satisfactory results. 相似文献