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A direct and much simpler way was developed for the diastereoselective synthesis of spiro cyclopropan‐1,3′‐oxindoles from indolin‐2‐one/N‐protected indolin‐2‐ones and bromonitroalkene. The fused restrained cyclopropanes were obtained with high diastereomeric ratios (upto >99:1) and in reasonable to high isolated chemical yields (upto 94%). 相似文献
43.
Two new cadmium(II)–terephthalate complexes, ∞1{[Cd2(μ-terephthalate)2(L1)2]·9H2O} (1) and [{Cd(H2O)(L2)}2(μ-terephthalate)](terephthalate) · 10H2O (2), where L1 = (E)-N1,N1-diethyl-N2-(1-(pyridin-2-yl)ethylidene)ethane-1,2-diamine; L2 = N,N′-bis-(1-pyridin-2-yl-ethylidene)-ethane-1,2-diamine; have been synthesized by a conventional solution method. Characterization by single crystal X-ray crystallography shows that compound 1 is composed of 1-D polymeric zig-zag chains with distorted pentagonal-bipyramidal cadmium centers. Compound 2 consists of centrosymmetric dinuclear complexes with a distorted pentagonal-bipyramidal cadmium center in which one terephthalate ligand bridges the metal centres and another terephthalate anion with water of crystallization forms a H-bonding network. 相似文献
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Dispersion polymerization of acrylamide at 40 degrees C in t-butyl alcohol-water media of varying composition (50 to 90 vol% alcohol) using a partial isopropyl ester of poly(vinyl methyl ether-alt-maleic anhydride) as the stabilizer has been studied. The isopropyl ester derivative proves to be a better stabilizer than its precursor polymer. However, the particles were polydisperse in size. The number average diameter of the particles increases linearly with the solubility parameter of the dispersion medium. Dispersions of nanoparticles of polyacrylamide are produced when the t-butyl alcohol content of the dispersion medium is 90% by volume. Comparison of the particle diameter measured by transmission electron microscopy with that measured by dynamic light scattering in acetone reveals a thickness of the hairy stabilizer layer on the dispersion particles of 31 nm. 相似文献
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Suparna Baksi Swati Dutta Michael G.B. Drew 《Journal of organometallic chemistry》2007,692(5):1025-1032
Reaction of 2-(2′-hydroxyphenylazo)phenol with [Rh(PPh3)3Cl] in refluxing benzene in presence of triethylamine afforded a red complex in which the ligand is coordinated to rhodium as a tridentate O,N,O-donor. However, similar reaction of [Rh(PPh3)3Cl] with 2-(2′-carboxyphenylazo)-4-methylphenol yielded two complexes, viz. a blue one and a green one. In both the complexes the ligand is coordinated as C,N,O-donor. However, in the blue complex orthometallation takes place from the ortho-carbon atom, which bears -COOH group via decarboxylation and in green one orthometallation occurs from the other ortho-carbon. Structures of all the three complexes were determined by X-ray crystallography. In all the three complexes rhodium is sharing the equatorial plane with the tridentate ligand and a chloride, and the two triphenylphosphines are axially disposed. All of the complexes show intense MLCT transitions in the visible region. Cyclic voltammetry on these complexes shows a Rh(III)-Rh(IV) oxidation on the positive side of SCE and a reduction of the coordinated azophenolate ligand on the negative side. 相似文献
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By incorporating an isolator at an appropriate location, it is shown that it is possible to realize an efficient single-pass superfluorescent-doped fiber source with a major fraction of its emitted power in the forward direction. A theoretical model to estimate the performance of such a superfluorescent source (SFS) has been suggested and verified with experiments performed on an erbium-doped fiber in a novel pump bypass SFS configuration. Results on design issues such as optimum location of the isolator, pump power requirements, and spectral characteristics are also presented. 相似文献
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Karmakar Koushik Saif Sohail Das Priya Neogy Sarmistha Biswas Suparna 《Wireless Personal Communications》2022,123(1):325-356
Wireless Personal Communications - Health monitoring systems based on Sensors, IoT and Cloud server have gained popularity in recent time. In this work patient either wear small sensors or they are... 相似文献
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Basu Suparna Singh Sanjay K. Singh Umesh 《Methodology and Computing in Applied Probability》2019,21(4):1377-1394
Methodology and Computing in Applied Probability - This article presents different estimation procedure for inverse Lindley distribution for Type-I hybrid censored data. We have obtained the... 相似文献
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Functionalized membranes containing carboxylate, phosphate and sulfonate groups were prepared by UV-initiator induced graft polymerization of the functional monomer (acrylic acid, ethylene glycol methacrylate phosphate (EGMP) and 2-acrylamido-2-methyl-1-propane sulfonic acid) with a crosslinker (methylenebisacrylamide) in the pores of poly(propylene) host membranes. The functionalized membranes thus obtained were characterized by gravimetry, FTIR spectroscopy, radiotracers and scanning electron microscopy for the degree of grafting and water uptake, presence of functional groups, ion-exchange capacity, and physical structure of the membranes, respectively. The uptakes of Cs+, Ag+, Sr2+, Cd2+, Hg2+, Zn2+, Eu3+, Am3+, Hf4+ and Pu4+ ions in the functionalized membranes were studied as a function of acidity of the equilibrating aqueous solution. Among the functionalized membranes prepared in the present work, the EGMP-grafted membrane (with phosphate groups) showed acid concentration dependent selectivity towards multivalent metal ions like Eu3+, Am3+, Hf4+ and Pu4+. The solvent extraction studies of EGMP monomer in methyl isobutyl ketone (MIBK) solvent indicated that divalent and trivalent metal ions form complexes with EGMP in 1:2 proportion, but the distribution coefficients of trivalent metal ions were significantly higher that for the divalent ions. The uptakes of Eu3+ ions in monomeric EGMP (dissolved in MIBK) and polymeric EGMP (in the forms of crosslinked gel and membrane) were studied as a function of concentration of H+ ions in the equilibrating solution. This study indicated that polymeric EGMP has better binding ability towards Eu3+ as compared to monomeric EGMP. The variation of distribution coefficients of Eu3+/Am3+ in gel and membrane as a function of H+ ion concentration in the equilibrating aqueous solution indicated that ionic species held in the membrane and gel were not same. These results indicated that proximity of functional groups (phosphate) plays an important role in metal ion binding with polymeric EGMP. 相似文献
50.
Suparna Bhattacharya Asim K. Bera S. Ghosh S. Chakraborty B.P. Mukhopadhyay A. Pal Asok Banerjee 《Journal of chemical crystallography》2000,30(10):655-663
The crystal structure of a unidecahydrated cocomplex between two Inosine-5-monophosphates (IMP) and one L-glutamic acid has been determined by X-ray crystallographic methods. The crystal belongs to the monoclinic space group P21 with cell dimensions a = 8.650(1), b = 21.900(1), c = 12.370(1) Å, and = 110.4°(9). This structure reveals extensive hydrogen bonding of glutamic acid to the nucleotide through direct and water-mediated interactions. The phosphate oxygens (O3B and O1B) seem to prefer nonspecific interaction with the functional sites of glutamic acid (OE2 ······O1B = 1.78 Å, NA······O3B = 2.73 Å, OH······O3B = 3.06 Å), whereas the bases prefer specific (O······N3B = 2.88 Å) binding. A solvent mediated N7A···W5···N7B hydrogen bond used for stabilization of the stacked purine bases has been observed as in other amino acid–nucleotide cocrystals. Glutamic acid occupies the same hydrophilic region in the nucleotide cocrystal as was found in glutamine–inosine monophosphate (Gln–IMP) and in serine–inosine monophosphate (Ser–IMP) complexes through substantial replacement of free and bound water molecules. This points to the dynamic hydrogen bonding nature of the water molecules and their stereochemical cooperation for the placement of amino acid through the polycoordination within the crystal. 相似文献