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111.
Verbalactone, a new macrocyclic dilactone was synthesized efficiently in a steroselective manner involving a Barbier-Grignard reaction, a Sharpless asymmetric dihydroxylation, monotosylation, epoxidation, ring opening of the epoxide, hydrolysis and lactonization. A δ-lactone, (+)-(3R,5R)-3-hydroxy-5-decanolide was also formed along with the dimeric lactone. 相似文献
112.
Fabrication of transparent and flexible carbon‐doped ZnO field emission display on plastic substrate 下载免费PDF全文
Transparent and flexible carbon doped ZnO (C:ZnO) field emission device was successfully fabricated on an arylite substrate. Excellent adhesion of deposited C:ZnO on the flexible substrate was achieved with low sputtering power and Ar flow rate. In the fabricated device, nanostructured C:ZnO and as‐deposited thin films were used as field emitter and phosphor screen, respectively. The C:ZnO thin film showed a transparency of about 80% at 550 nm wavelength and average sheet resistance of 1.96 kΩ/□. The C:ZnO phosphor screen emitted red light during the field emission measurement, correlating the dominant cathodoluminescence peak at 646 nm. Thus, a promising transparent and flexible field emission display can be realized with C:ZnO based material.
113.
Avijit Maiti Jessica Stubbe Nicols I. Neuman Pankaj Kalita Prakash Duari Carola Schulzke Vadapalli Chandrasekhar Biprajit Sarkar Anukul Jana 《Angewandte Chemie (International ed. in English)》2020,59(17):6729-6734
Diradicals have been of tremendous interest for over a century ever since the first reports of p‐ and m‐phenylene‐bridged diphenylmethylradicals in 1904 by Thiele and 1915 by Schlenk. Reported here are the first examples of cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon, a Kekulé diradical, and Schlenk's hydrocarbon, a non‐Kekulé diradical, without using CAAC as a precursor. The CAAC analogue of Thiele's hydrocarbon has a singlet ground state, whereas the CAAC analogue of Schlenk's hydrocarbon contains two unpaired electrons. The latter forms a dimer, by an intermolecular double head‐to‐tail dimerization. This straightforward synthetic methodology is modular and can be extended for the generation of redox‐active organic compounds. 相似文献
114.
A class of higher order compact (HOC) schemes has been developed with weighted time discretization for the two‐dimensional unsteady convection–diffusion equation with variable convection coefficients. The schemes are second or lower order accurate in time depending on the choice of the weighted average parameter μ and fourth order accurate in space. For 0.5?μ?1, the schemes are unconditionally stable. Unlike usual HOC schemes, these schemes are capable of using a grid aspect ratio other than unity. They efficiently capture both transient and steady solutions of linear and nonlinear convection–diffusion equations with Dirichlet as well as Neumann boundary condition. They are applied to one linear convection–diffusion problem and three flows of varying complexities governed by the two‐dimensional incompressible Navier–Stokes equations. Results obtained are in excellent agreement with analytical and established numerical results. Overall the schemes are found to be robust, efficient and accurate. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
115.
Here, we propose a new complex path to achieve better absorption during the propagation of a wavepacket. In the proposed modified smooth exterior scaling (SES) method, scaling function, θ(x), has been chosen as a real function rather than complex (as used in a conventional smooth exterior scaling method). It greatly reduces the artificial reflections from the boundary edges. This modified SES method is applied to study the multiphoton dissociation of H(2)(+) in intense laser field. The resonance states are calculated accurately. 相似文献
116.
A magnetic field-induced singlet-to-antiferromagnetic quantum magnetic phase transition has been considered. It has been shown
that the phenomenon can be described within an approach similar to the Landau theory of phase transitions. The case of an
oblique magnetic field has been studied and the critical field-angle phase diagram has been determined. The phase diagram
agrees with the experimental one observed in DTN. 相似文献
117.
Tirtha Bhattacharjee Pranjit Barman Tapan Thakuria Rupam Sarma Ranjan Dutta Kalita Bipul Sarma 《Heteroatom Chemistry》2013,24(6):502-509
4′‐Methylazobenzene‐2‐sulfenyl thio‐cyanate (MABS‐SCN) was synthesized in an aqueous medium and characterized by 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and elemental analysis. The crystal structure was confirmed by single crystal X‐ray diffraction and its geometry was optimized in ground state by Hartree–Fock model and (B3LYP) density functional theory, and in solution (ethanol) using polarized continuum model at restricted HF using the basis set 6–31+G*. The compound crystallizes in orthorhombic space group Pbca, with unit cell parameters a = 7.165 (7) Å, b = 18.846 (2) Å, c = 20.379 (2) Å, V = 2752.1 (5) Å3, and Z = 8. It attains a planar thiadiazolium salt structure due to strong ortho azo–sulfur interaction imparting exceptional thermal stability, nonreactive solubility in aqueous medium, and high melting crystalline solid nature. A weak intramolecular C H…S type interaction, one C H…S type, four C H…N type intermolecular hydrogen bonds, and van der Waal's interactions are believed to be the stabilizing force for the crystal structure. MABS‐SCN was also tested for antimicrobial activity. 相似文献
118.
A. A. Timopheev S. M. Ryabchenko V. M. Kalita A. F. Lozenko P. A. Trotsenko O. V. Stognei A. V. Sitnikov 《Physics of the Solid State》2011,53(3):494-503
This paper reports on the results of the magnetostatic measurements for Co-Al-O nanogranular films over a wide range of concentrations
of the ferromagnetic component x. It has been revealed that grains in the films are characterized by the growth-induced anisotropy with easy axes directed
perpendicular to the film plane. The maximum field of the single-grain perpendicular anisotropy reaches ∼2.5 kOe for samples
in the vicinity of the percolation threshold (x ≈ 61 at % Co). It has been established that the characteristic features of the superparamagnetic behavior of an ensemble
of oriented Stoner-Wohlfarth particles are retained for the sample with x ≈ 61 at % Co in the presence of the demagnetization field associated with the net magnetization of the film. The influence
of the demagnetization field of the film on the shape of the magnetization reversal curves, the coercivity, and the blocking
temperature has been investigated and simulated. The results of the simulation are consistent with the experimental data. 相似文献
119.
meso‐Pyrrole‐Substituted 22‐Oxacorroles: Building Blocks for the Synthesis of BODIPY‐Bridged 22‐Oxacorrole Dyads 下载免费PDF全文
Hemanta Kalita Prof. Mangalampalli Ravikanth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7399-7402
Novel boron‐dipyrromethene (BODIPY)‐bridged 22‐oxacorrole dyads, using meso‐pyrrolyl 22‐oxacorrole as a key synthon, have been synthesized. The reactivity of the meso‐pyrrolyl group of 22‐oxacorrole was exploited to synthesize the first examples of BODIPY‐bridged 22‐oxacorrole dyads in ≈40 % yield. The dyads are stable and exhibited interesting spectral and electrochemical properties. 相似文献
120.
Mohosin Layek A.V. Dhanunjaya Rao Dipak Kalita Aminul Islam Manojit Pal 《Tetrahedron letters》2009,50(34):4878-238
We report copper-catalyzed intramolecular cyclization of 8-alkynyl-1,2,3,4-tetrahydroquinolines, obtained via a Pd/C-mediated Sonogashira coupling in water, to afford 2-substituted 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolines. Further functionalization of the compounds synthesized was carried out under Heck, Sonogashira, and Suzuki reaction conditions. 相似文献