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41.
42.
A Copper‐Based Metal–Organic Framework Acts as a Bifunctional Catalyst for the Homocoupling of Arylboronic Acids and Epoxidation of Olefins 下载免费PDF全文
Srinivasulu Parshamoni Jyothi Telangae Suresh Sanda Prof. Dr. Sanjit Konar 《化学:亚洲杂志》2016,11(4):540-547
A copper(I)‐based metal–organic framework ({[Cu2Br2(pypz)]n?nH2O} (Cu—Br–MOF) [pypz=bis[3,5‐dimethyl‐4‐(4’‐pyridyl)pyrazol‐1‐yl] methane] has been synthesized by using an elongated and flexible bridging ligand. The structure analysis reveals that each pypz ligand acts as a tritopic ligand connected to two Cu2Br2 dimeric units, forming a one‐dimensional zig–zag chain, and these chains further connected by a Cu2Br2 unit, give a two‐dimensional framework on the bc‐plane. In the Cu2Br2 dimeric unit, the copper ions are four coordinated, thereby possessing a tetrahedral geometry; this proves to be an excellent heterogeneous catalyst for the aerobic homocoupling of arylboronic acids under mild reaction conditions. This method requires only 3 mol % of catalyst and it does not require any base or oxidant—compared to other conventional (Cu, Pd, Fe, and Au) catalysts—for the transformation of arylboronic acids in very good yields (98 %). The shape and size selectivity of the catalyst in the homocoupling was investigated. The use of the catalyst was further extended to the epoxidation of olefins. Moreover, the catalyst can be easily separated by simple filtration and reused efficiently up to 5 cycles without major loss of reactivity. 相似文献
43.
Yarram Narasimha Reddy Tenkayala Navya Kumari Pradeepkumar Thota Perla Jyothi Ajay Kumar Gupta 《Tetrahedron letters》2018,59(2):160-162
A new chemoenzymatic route for the preparation of cryptocaryalactones natural products using a kinetic resolution process as the key step is described. Novozyme-435 catalyzed hydrolysis of the prochiral (±)-monoester 7 afforded the precursors of cryptocaryalactones with high enantiomeric excess and excellent yields. The compounds (4S,6S)-7 and (4R,6R)-7 were converted to (+)-(6R,2′S)-cryptocaryalactone (1) and (?)-(6S,2′R)-cryptocaryalactone (2), respectively by employing Wittig-olefination, lactonization and acylation reactions. 相似文献
44.
The extraction characteristics of some selected metals from an aqueous buffered solution by LIX51. a fluorinated commercial
β-diketone extractant, have been investigated. The pH 1/2 (pH at which 50% of the metal ion is extracted) and the logK
ex
values for the extracted metals by 5% (v/v) L1X51 in methylisobutylkctone(MIBK) have been obtained. The order of extraction
of metals with LIX51 as a function of pH 1/2 value is: Cu(II) < Pd(II) < Co(II) < Zn(II) < Fe(H) < Ph(II) < Mn(II) < Cd(II)
< Ni(II). 相似文献
45.
M. Siva Pratap Reddy V. Rajagopal Reddy I. Jyothi Chel‐Jong Choi 《Surface and interface analysis : SIA》2011,43(9):1251-1256
Schottky rectifiers are fabricated on n‐type GaN using Ni/Pd metallization scheme and its characteristics have been investigated by current‐voltage (I‐V), Capacitance‐Voltage (C‐V), X‐Ray Diffraction (XRD) and SIMS measurements as a function of annealing temperature. The calculated Schottky barrier height of the as‐deposited contact was found to be 0.60 eV (I‐V), 0.71 eV (C‐V) with an ideality factor of 1.44. However, the barrier height slightly increases after annealing at 300, 400 and 500 °C. On the basis of the experimental results, a high‐quality Schottky contact with barrier height and ideality factor of 0.81 eV (I‐V), 0.88 eV (C‐V) and 1.13 respectively, can be obtained after annealing at 600 °C for 1 min in a nitrogen atmosphere. Further, after annealing at 700 °C, it is found that the barrier height slightly decreased to 0.74 eV (I‐V) and 0.85 eV (C‐V). From the above observations, one can note that Ni/Pd Schottky contact exhibits excellent electrical properties after a rapid thermal annealing at 600 °C. According to the SIMS and XRD analysis, the formation of gallide phases at the Ni/Pd/n‐GaN interface could be the reason of the barrier height increase at elevated annealing temperatures. The Atomic Force Microscopy (AFM) results show that the overall surface morphology of Ni/Pd Schottky contacts on n‐GaN is fairly smooth. The above observations reveal that Ni/Pd Schottky metallization scheme was a good choice for the fabrication of high‐temperature and high‐power device applications. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
46.
Dodecylsulphate-intercalated zinc hydroxysalt, Zn5(OH)8(DS)2·mH2O delaminates to give monolayer colloidal dispersions in alcohols such as 1-butanol and ethylene glycol. The extent of delamination and the stability of the colloidal dispersion are comparable to those of layered double hydroxides. The solvothermal decomposition of the colloidal dispersion of the hydroxysalt in ethylene glycol yields a bimodal ZnO having a nanotubular structure decorated with nanosheets. 相似文献
47.
Jyothi Sowdari Sreenivasulu Thata Yamini Gudi Padmavathi Venkatapuram Padmaja Adivireddy 《Journal of heterocyclic chemistry》2020,57(4):1882-1892
Some new benzoxazolyl isoxazoles, benzothiazolyl isoxazoles and benzimidazolyl isoxazoles connected by amide bonds ( 7-9 ) were prepared from N-benzazolylcarbamoylmethylcinnamamides ( 1-3 ) adopting eco-friendly synthetic methodologies. In fact, cycloaddition of nitrile oxide generated from araldoxime using iodosobenzene and cetyltrimethylammonium bromide to 1-3 followed by treatment with iodine in dimethyl sulfoxide led to the formation of title compounds with good yields and in shorter reaction times. The structures of all the synthesized compounds were confirmed by spectral parameters, viz, IR, NMR, and mass spectra and were assayed for antimicrobial activity. Among all the tested compounds, 8a and 8c displayed excellent antibacterial activity, whereas 9a and 9c showed promising antifungal activity. 相似文献
48.
Substituted 1H-benzimidazoles, pyrazolones, and pyrazoles have been synthesized by the condensation of ortho-phenylenediamines and phenylhydrazines, respectively, with ethyl 4-chloro-3-oxobutanoate in good yields. The present approach is novel, straightforward, and being reported for the first time with ethyl 4-chloro-3-oxobutanoate. 相似文献
49.
Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO2:LaPO4 ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO2 in TiO2-LaPO4 composite precursors was found to be stable even on annealing at 800 °C. The glass substrates, coated with TL1 (TiO2-LaPO4 composition with 1 mol% LaPO4) and TL50 (composite precursor containing TiO2 and LaPO4 with molar ratio 1:1) sols and annealed at 400 °C, produced contact angles of 74° and 92°, respectively, though it is only 62° for pure TiO2 coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 °C, has shown the highest UV photoactivity with an apparent rate constant, kapp=24×10−3 min−1, which is over five times higher than that observed with standard Hombikat UV 100 (kapp=4×10−3 min−1). The photoactivity combined with a moderate contact angle (85.3°) shows that this material has a promise as an efficient self-cleaning precursor. 相似文献
50.
Chung Kyeong Woo Yoon Ho-Sung Kim Chul-Joo Jyothi Rajesh Kumar 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):245-255
Journal of Radioanalytical and Nuclear Chemistry - Separation and purification of thorium from monazite leach liquors was investigated by counter current extraction process. The Primene JM-T... 相似文献