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91.
Vijai K. Rai Fooleswar Verma Mansingh Satnami Manorama Singh Ankita Rai 《Tetrahedron letters》2018,59(18):1783-1786
A novel and efficient three-component coupling strategy for stereoselective synthesis of highly substituted tetrahydropyridines (THP) is reported in high yield (83–94%) with excellent diastereoselectivity (95–99%) in favor of anti-isomer. The reaction proceeds via sequential iminium-iminium-enamine mediated formation of three consecutive CC, CC and CN bonds in one-pot through reaction of [E]-α-cyano/nitro unsaturated aldehyde, activated methylene and aldimine/phenyl-N-tosyl-methanimine and opens up a new aspect for the utility of Morita-Baylis-Hillman (MBH) adducts in THP synthesis. 相似文献
92.
Ankita Singh Devla Bimal Rajesh Kumar Vipin K. Maikhuri M. Thirumal Nihar Nalini Senapati 《合成通讯》2013,43(18):2339-2346
The synthesis of novel 4-furano-coumarins and 3-furano-chromones has been achieved using silver-mediated oxidative C–H/C–H functionalization of 4-ethynylcoumarin/3-ethynylchromone with ethyl acetoacetate in 80%–90% and 82%–90% yields, respectively. The structure of the synthesized compounds was established on the basis of their spectral data analysis and the structure of one of the 4-furano-coumarins has been further confirmed on the basis of its X-ray crystallographic study. All eight synthesized 4-furano-coumarins and 3-furano-chromones exhibited moderate antitubercular activity against sensitive reference strain H37Rv of Mycobacterium tuberculosis. 相似文献
93.
We present here the effect of degradation on electronic properties of polymer solar cells. Investigations were performed on two types of solar cells based on the bulk‐heterojunction network of poly(3‐hexylthiophene) and phenyl [6,6] C61 butyric acid methyl ester, one with slow degradation whereas other with faster degradation. Samples were prepared in identical conditions with controlled atmosphere, but for faster degradation, one of the samples was exposed to ambient air (rich in O2 and H2O molecules) before deposition of top metal electrode. The sample with slow degradation showed linear degradation in short circuit current density (Jsc), whereas the sample with faster degradation exhibited exponential degradation in Jsc. Linear degradation happens due to degradation in the active layer only whereas the exponential degradation is because of through degradation of the solar cell. The effect of degradation is investigated on different diode parameters. Because of different degradation processes in the two samples, the variations in diode parameters with time are different. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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95.
A novel version of the Biginelli reaction using an unprotected aldose as a biorenewable aldehyde component and 2-methyl-2-phenyl-1,3-oxathiolan-5-one as a mercaptoacetylating active methylene building block with urea/thiourea is reported. The reaction is nanoclay-catalysed, expeditious and effected under solvent-free microwave irradiation conditions in a one-pot procedure to yield diastereoselectively, thiosugar-annulated multifunctionalized dihydropyrimidines via intramolecular domino cyclocondensation reactions of an isolable intermediate. 相似文献
96.
Emission properties of manganese-doped ZnS nanocrystals 总被引:1,自引:0,他引:1
Sapra S Prakash A Ghangrekar A Periasamy N Sarma DD 《The journal of physical chemistry. B》2005,109(5):1663-1668
We have performed steady-state and time-resolved fluorescence studies on undoped and Mn-doped ZnS nanocrystals with approximately 16 A diameter. While there is no band-edge emission, the intensity of the steady-state blue fluorescence from ZnS surface states decreases upon Mn incorporation, which gives rise to an orange emission. These results show that Mn incorporation competes very effectively with the donor-acceptor surface states for the energy transfer from the electron-hole pair excited across the band gap. In both undoped and doped samples, the time-resolved fluorescence studies establish the presence of a distribution of decay lifetimes possibly due to a number of emission centers in the nanocrystals. A faster short-time decay of the blue emission in the Mn-doped samples compared to that in the undoped sample suggests an additional decay channel for the surface states via an energy transfer from these states to the dopant levels. 相似文献
97.
Conformational changes of amide cavitands A – C were investigated at varied temperatures and in several solvents. While cavitands A and B , with comparatively smaller substituents such as Et and iPr, were always in vase conformation in non‐polar solvents such as CDCl3, CD2Cl2, (D8)THF, and C6D6, their thermoswitching (vase to kite) was observed in polar solvents such as (D7)DMF and (D6)DMSO or in the presence of acid (TFA) and H‐bonding inhibitor (TFE). Intra‐ and interannular H‐bonds of A and B were clearly observed by low‐temperature 1H‐NMR spectra in CDCl3. No conformational change of cavitand C with bigger substituent (tBu) was observed under any tested temperature range and in polar or non‐polar solvents; C was always in the kite conformation. 相似文献
98.
Manorama Singh Smita R. Bhardiya Ambika Asati Harendra Sheshma Ankita Rai Vijai K. Rai 《Electroanalysis》2021,33(2):464-472
Herein, we report construction of a ferrocene-reduced graphene oxide-Mn spinel modified glassy carbon electrode (Fc−G/Mn3O4/GCE) as a sensitive electrochemical probe for hydrazine detection via its oxidation. The synergistic effect of ferrocene, graphene oxide and Mn3O4 provides it a great electrocatalytic effect. The electrochemical investigations of Fc−G/Mn3O4/GCE were studied using cyclic voltammetry, while differential pulse voltammetry was utilized for recording the electrocatalytic sensing of hydrazine. The prepared Fc−G/Mn3O4 offers a platform for sensitive and selective detection of low-level hydrazine in two linear ranges from 0.045 to 108 μM and 108 to 653 μM with limit of detection 8.5 nM. Real sample analysis was also performed in local industrial water samples with satisfactory recovery results. 相似文献
99.
Arkabandhu Chowdhury Hamim Zafar B. K. Panigrahi K. R. Krishnanand Ankita Mohapatra Zhihua Cui 《Memetic Computing》2014,6(2):85-95
Dynamic economic dispatch (DED) is one of the major planning problem in a power system. It is a non-linear optimization problem with various operational constraints, which includes the constraints of the generators operating characteristics and the system constraints. Its principal aim is to minimize the cost of power production of all the participating generators over a time horizon of 24 h, while satisfying the system constraints. This problem deals with non-convex characteristics if generation unit valve-point effects are taken into account. The paper intends to solve the DED problem with valve-point effects, using our modified form of Local-best variant of Particle Swarm Optimization (Lbest PSO) algorithm. We have tested our algorithm on 5-unit, 10-unit and 110-unit test system with non-smooth fuel cost functions to prove the effectiveness of the suggested method over different state of the art methods. 相似文献
100.
A catalyst-free multicomponent reaction (MCR) capable of affording a wide range of novel benzo[a][1,3]oxazino[6,5-c]phenazine derivatives via one pot two-step domino protocol, in water is reported. Catalyst-free conditions along with green solvent system make the process ecofriendly as well as economical. Simple reaction conditions, easy work-up isolation, and purification of products are the significant advantages of the present protocol. 相似文献