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991.
992.
Synthesis of novel isoxazole-benzoquinone hybrids via 1,3-dipolar cycloaddition reaction as key step
P. Ravi Kumar Manoranjan BeheraK. Raghavulu A. Jaya ShreeSatyanarayana Yennam 《Tetrahedron letters》2012,53(32):4108-4113
An efficient method for the preparation of novel 2-(5-arylisoxazol-3-yl)cyclohexa-2,5-diene-1,4-dione hybrids via 1,3-dipolar cycloaddition followed by an oxidation reaction using ceric ammonium nitrate (CAN) has been described. Using this method, various aryl as well as alkyl substituted isoxazole-benzoquinone hybrids were synthesized in high yields. 相似文献
993.
Dipravath Kumar SethSamaresh Bhattacharya 《Polyhedron》2011,30(15):2438-2443
The reactions of N-(aryl)pyridine-2-aldimines (L-R; R = OCH3, CH3, H, Cl and NO2), derived from pyridine-2-aldehyde and para-substituted anilines, with CuI in methanol under ambient conditions afford a series of brown complexes of the type [{Cu(L-R)I}2]. The structure of the [{Cu(L-OCH3)I}2] complex has been determined by X-ray crystallography. In these dimeric complexes the two copper centers are linked through an iodo-bridge, and the L-R ligands are coordinated to the metal center through the pyridine-nitrogen and imine-nitrogen. All the complexes show characteristic 1H NMR signals and intense MLCT transitions in the visible region. These complexes also show an emission near 465 nm, whilst they are excited at 340 nm, with relatively poor quantum yields (φ ∼0.002 at 298 K). Cyclic voltammetry on all the complexes shows two successive Cu(I)-Cu(II) oxidations on the positive side of SCE, and a reduction of the coordinated imine ligand on the negative side. These copper(I) complexes are found to efficiently catalyze Suzuki type C-C coupling reactions. 相似文献
994.
Biosorption of Cr(VI) ions from aqueous solutions: kinetics, equilibrium, thermodynamics and desorption studies 总被引:2,自引:0,他引:2
Cr(VI) is a major water pollutant from industrial effluent whose concentration is to be reduced within the permissible limit. Present study reports a systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process. The adsorption kinetic data were best described by pseudo-second order model. The values of mass transfer coefficient for Cr(VI) adsorption indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast. The effective diffusivity of Cr(VI) removal for all the adsorbents were of the order of 10(-10) m(2)/s which suggested chemisorption of the process. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion. Maximum monolayer adsorption capacities onto the natural adsorbents used were comparable to the other natural adsorbents used by other researchers. The thermodynamic studies and sorption energy calculation using Dubinin-Radushkevich isotherm model indicated that the adsorption processes were endothermic and chemical in nature. FT-IR studies were carried out to understand the type of functional groups responsible for Cr(VI) binding process. Desorption study was carried out with different concentration of NaOH solutions. Application study was carried out using electroplating industrial wastewater. 相似文献
995.
Efficacious Anticancer Drug Delivery Mediated by a pH‐Sensitive Self‐Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor
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Parikshit Moitra Krishan Kumar Prof. Paturu Kondaiah Prof. Santanu Bhattacharya 《Angewandte Chemie (International ed. in English)》2014,53(4):1113-1117
We present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy. 相似文献
996.
Convenient and straightforward tetrabutylammonium bromide (TBAB), benzyltrienthylammonium chloride (BTEAC), and cetyltrimethylammonium bromide (CTAB) catalyzed synthesis of 1,4-dihydropyridines (1,4-DHPs) in water was established for the first time. The catalytic potential of phase-transfer catalysts (PTCs) in three different concentrations was envisioned. Aryl aldehydes and hetero aryl aldehydes afforded good yields of 1,4-DHPs in TBAB and BTEAC reactions. In particular, furfuraldehyde and thienyl-2-carbaldehyde produced excellent yields. Isolation of the products through nonchromatographic methods, good to excellent yields, and benign reaction conditions are the major advantages of this protocol. 相似文献
997.
Poulomi Majumdar Anita Pati Rajani K. Behera Ajaya Kumar Behera 《Journal of heterocyclic chemistry》2013,50(3):703-712
A Cannizzaro‐type reaction of tetrahydro‐5(1H)‐quinolinones with para substituted benzaldehydes in the presence of a base formed the corresponding quinoline and aryl methanol rather than arylidene derivatives because of the oxidation of tetrahydroquinoline and reduction of benzaldehydes as a result of unprecedented hydride transfer from tetrahydroquinoline to arylaldehydes. The reaction proceeds best with the participation of substituents with +M effect in substrate molecule. 相似文献
998.
999.
An electrochemical pathway to prepare circular planar 90Sr/90Y sources for the calibration of surface contamination monitors 总被引:1,自引:0,他引:1
Manoj Kumar Shyamala S. Gandhi J. Nuwad J. Udhayakumar Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):709-719
In this communication, we describe a novel method to prepare circular planar 90Sr/90Y sources (? = 16 mm) exploiting the intrinsic properties of the anodized titanium to electro-deposit predicted quantity of 90Sr activity from an aqueous solution. The influences of various experimental parameters such as pH of the electrolyte, applied current density, electrodeposition time and carrier strontium concentration were thoroughly investigated to arrive at a condition resulting optimal deposition of the 90Sr/90Y activity on the substrate. An optimized electrochemical procedure to prepare ~3.7 MBq (~0.1 mCi) of circular planar 90Sr/90Y sources commensurate with regulatory safety requirement has been the positive outcome. 相似文献
1000.
Theodosis Giousis Georgia Potsi Antonios Kouloumpis Konstantinos Spyrou Yiannis Georgantas Nikolaos Chalmpes Konstantinos Dimos Myrsini‐Kiriaki Antoniou Georgios Papavassiliou Athanasios B. Bourlinos Hae Jin Kim Vijay Kumar Shankarayya Wadi Saeed Alhassan Majid Ahmadi Bart J. Kooi Graeme Blake Daniel M. Balazs Maria A. Loi Dimitrios Gournis Petra Rudolf 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2021,133(1):364-369
Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (Eg) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells. 相似文献