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51.
A mild, selective, and green method for the reduction of unsaturated carboxylic acids with sodium borohydride–Raney nickel (W6) system in water is reported. This method is practical and safe and avoids use of organic solvents. 相似文献
52.
Antiaromatic molecules have been predicted to exhibit increased electron transport properties when placed between two nanoelectrodes compared to their aromatic analogues. While some studies have demonstrated this relationship, others have found no substantial increase. We use atomistic simulations to establish a general relationship between the electronic spectra of aromatic, antiaromatic, and quinoidal molecules and illustrate its implications for electron transport. We compare the electronic properties of a series of aromatic-antiaromatic counterparts and show that antiaromaticity effectively p-dopes the aromatic electronic spectra. As a consequence, the conducting properties of aromatic-antiaromatic analogues are closely related. For similar attachment points to the electrodes, an interference feature is expected in the HOMO-LUMO gap of one whenever it is absent in the other one. We demonstrate how the relative conductance of aromatic-antiaromatic pairs can be tuned and even reversed through the choice of chemical linker groups. Our work provides a general picture relating connectivity, (anti)aromaticity, and quantum interference and establishes new design rules for single molecule circuits. 相似文献
53.
Loganathan Ramu Narendra Kuppan Keralapura Parthasarathy Ramesh Rattihalli Chandramani Daivagna Ramananda 《Magnetic resonance in chemistry : MRC》2019,57(8):499-505
35Cl NQR frequency and spin lattice relaxation time in 3,4-dichloronitrobenzene have been measured as a function of temperature and pressure. Two NQR signals were observed in the temperature range 77 to 300 K and pressure up to 5.1 kbar at 300 K. The contributions to the relaxation from the torsional motion of the molecule and reorientational motion of the nitro group have been analyzed on the basis of the Woessner and Gutowsky model. The temperature dependence of the average torsional lifetimes of the molecules, transition probabilities, and the activation energy for the reorientation of the nitro group was estimated. The pressure dependence of the NQR frequency in 3,4-Dichloronitrobenzene shows a nonlinear increase in NQR frequency with increase in pressure, indicating increased contribution from the static effects at higher pressures. A thermodynamic analysis of the data was carried out to determine the constant-volume temperature coefficients of the NQR frequency. The spin–lattice relaxation was found to be weakly dependent on pressure. 相似文献
54.
Vinodini Shaktawat Dinesh Patidar Kananbala Sharma Narendra S. Saxena Thansewar. P. Sharma 《Central European Journal of Chemistry》2009,7(4):769-773
Pure Polyaniline (EB) and Polyaniline doped with different protonic acids (ESs) were chemically synthesized using ammonium peroxydisulphate (APS) as an oxidant. Junctions have been prepared by evaporating chalcogenide materials (ZnSe, CdSe) on conducting polyaniline (EB & ESs) pellets using a vacuum evaporation technique. I–V characteristics of junctions have been studied at room temperature using the Keithley electrometer 6517A. I–V measurements show the rectification effect. A junction of ES[PO4 3?] may be preferred over the other junctions due to its low ideality factor and maximum rectification ratio. 相似文献
55.
56.
Narendra Prasad Brian K. Nicholson C. John McAdam 《Journal of organometallic chemistry》2010,695(17):1961-5456
2-Ferrocenyl-substituted pyrylium salts are produced when orthomanganated chalcones are reacted with ethynylferrocene in CCl4. When the reaction is carried out in benzene, intermediate ferrocenyl-substituted (η5-pyranyl)Mn(CO)3 species can be isolated which give the pyrylium cations on oxidation. The electrochemistry of the 2-ferrocenyl-pyrylium cations shows both oxidation (of the ferrocenyl) and reduction (of the pyrylium) processes, and the UV-visible spectra show a broad band at ca 680 nm which can be assigned to an intramolecular charge transfer transition. 相似文献
57.
Suzuki–Miyaura cross-coupling reactions of aryl halides with arylboronic acids were performed in predominantly aqueous media employing two mono- and two dinuclear cyclopalladated complexes as catalysts. These complexes are [Pd(HL)Cl] (I), [Pd(L)(PPh3)] (II), [Pd2(μ-dppb)(L)2] (III) and [Pd2(μ-dppf)(L)2] (IV); where H2L, dppb and dppf represent 4-methoxy-N′-(mesitylidene)benzohydrazide, 1,4-bis(diphenylphosphino)butane and 1,1′-bis(diphenylphosphino)ferrocene, respectively. The reactions were conducted using potassium carbonate as base in presence of tetrabutylammonium bromide (TBAB) at 70/90 °C in dimethylformamide–water (1:20) mixture. Among the four catalysts used, the dinuclear complex IV turned out to be the most effective and afforded moderate to excellent yields with broad substrate scope. 相似文献
58.
Faysal Benaskar Volker Engels Narendra Patil Jan Meuldijk Lumbertus A. Hulshof Jaap. C. Schouten Andrew E.H. Wheatley 《Tetrahedron letters》2010,51(2):248-5988
The action of nanoparticulate copper catalysts with a mean particle size of 10 nm in the Ullmann ether synthesis is reported using multimode microwave heating and employing stable chloropyridine salts and unactivated phenol, with stabilized copper nanoparticles outperforming other copper catalysts in terms of stability and reusability. 相似文献
59.
60.
Photolysis studies on MAg4I5 films are reported. The electrical conductivities of MAg4I5 films have been found to change when exposed to mercury light. This is explained on the basis of a model similar to Mott-Gurney theory of photolysis for silver halides. The formation of silver specks has been confirmed by photomicrographic studies. 相似文献