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31.
Study on One‐pot Biginelli‐like Synthesis of Pyrazolo[3,4‐d]pyrimidines in Bronsted Acidic Ionic Liquid Under Sonication and its Mechanism 下载免费PDF全文
Bhautik B. Thummar Umesh P. Tarpada Dipak K. Raval 《Journal of heterocyclic chemistry》2014,51(6):1740-1746
Pyrazolo[3,4‐d]pyrimidine derivatives were synthesized using ionic liquid, 1‐butylimidazolium tetrafluoroborate, under ultrasound irradiation at ambient condition without any added catalyst. Mechanistic pathway based on the catalytic role of ionic liquid has been proposed. This method offers the advantages of simple procedure, milder reaction condition, easier workup and improved yield over the conventional method. The ionic liquid could be recycled at least three times with marked retention in its activity. 相似文献
32.
P.N. Joshi N.K. Ramaswamy M.K. Raval T.S. Desai P.M. Nair U.C. Biswal 《Journal of photochemistry and photobiology. B, Biology》1993,20(2-3):197-202
Wheat seedlings, grown for 7 days in the light, were allowed to senesce in the light or dark, and the change in the photosystem II (PS II) photochemistry of chloroplasts isolated from the primary leaves of these seedlings was investigated. The decrease in oxygen evolution and the fast fluorescence results indicated that the impairment of PS II in the leaves of seedlings senescing in the light was different from that in the leaves of seedlings senescing in the dark. Thermoluminescence studies showed a structural modification in the QB protein of chloroplasts isolated from leaves senescing in the light and an alteration in the S state transition of chloroplasts isolated from leaves senescing in the dark. 相似文献
33.
The phonon spectra for liquid Li and Na have been computed through the phenomenological model of Bhatia and Singh for disordered
systems like liquids and glasses and the obtained results have been compared with the available data obtained by inelastic
neutron scattering (INS) and inelastic X-ray scattering (IXS) experiments. The effective pair potentials and their space derivatives
are important ingredients in the computation of the dispersion curves. The pair potentials are obtained using the pseudo-potential
theory. The empty core model proposed by Ashcroft is widely used for pseudo-potential calculations for alkali metals. But,
it is thought to be unsuitable for Li because of its simple 1s electronic structure. However, it can be used with an additional
term known as Born-Mayer (BM) core term. The influence of the BM core term on the phonon dispersion is discussed. The same
pseudo-potential formalism has been employed to obtain the dispersion relation in liquid Li0.61Na0.39 alloy. Apart from the phonon spectra, the Ashcroft-Langreth structure factors in the alloy are derived in the Percus-Yevick
approximation. 相似文献
34.
C.A. Fustin S. Haq A. Wingen C. Grgoire R. Raval P. Dumas J.S. Hannam D.A. Leigh P. Rudolf 《Surface science》2005,580(1-3):57-62
The adsorption of a benzylic amide [2]catenane on a Au(1 1 1) single crystal has been studied using infrared reflection absorption spectroscopy. The evolution of the infrared spectra during catenane deposition at different temperatures of the gold substrate (300 and 90 K) has been compared. Evidence of the catenane deformation upon chemisorption have been found at 300 K only. At 90 K the catenane is weakly adsorbed without any deformation. 相似文献
35.
Understanding the composition and stability of mixed water-hydroxyl layers is a key step in describing wetting and how surfaces respond to redox processes. Here we show that, instead of forming a complete hydrogen bonding network, structures containing an excess of water over hydroxyl are stabilized on Cu(110) by forming a distorted hexagonal network of water-hydroxyl trimers containing Bjerrum defects. This arrangement maximizes the number of strong bonds formed by water donation to OH and provides uncoordinated OH groups able to hydrogen bond multilayer water and nucleate growth. 相似文献
36.
CO oxidation on PtO2(110) has been studied using density functional theory calculations. Four possible reaction mechanisms were investigated and the most feasible one is the following: (i) the O at the bridge site of PtO2(110) reacts with CO on the coordinatively unsaturated site (CUS) with a negligible barrier; (ii) O2 adsorbs on the bridge site and then interacts with CO on the CUS to form an OO-CO complex; (iii) the bond of O-OCO breaks to produce CO2 with a small barrier (0.01 eV). The CO oxidation mechanisms on metals and metal oxides are rationalized by a simple model: The O-surface bonding determines the reactivity on surfaces; it also determines whether the atomic or molecular mechanism is preferred. The reactivity on metal oxides is further found to be related to the 3rd ionization energy of the metal atom. 相似文献
37.
38.
A Small Molecule Walks Along a Surface Between Porphyrin Fences That Are Assembled In Situ 下载免费PDF全文
Dr. Sam Haq Bareld Wit Hongqian Sang Dr. Andrea Floris Prof. Yu Wang Prof. Jianbo Wang Dr. Lluïsa Pérez‐García Prof. Lev Kantorovitch Prof. David B. Amabilino Prof. Rasmita Raval 《Angewandte Chemie (International ed. in English)》2015,54(24):7101-7105
An on‐surface bimolecular system is described, comprising a simple divalent bis(imidazolyl) molecule that is shown to “walk” at room temperature via an inchworm mechanism along a specific pathway terminated at each end by oligomeric “fences” constructed on a monocrystalline copper surface. Scanning tunneling microscopy shows that the motion of the walker occurs along the [1$\bar 1$ 0] direction of the Cu surface with remarkably high selectivity and is effectively confined by the orthogonal construction of covalent porphyrin oligomers along the [001] surface direction, which serve as barriers. Density functional theory shows that the mobile molecule walks by attaching and detaching the nitrogen atoms in its imidazolyl “legs” to and from the protruding close‐packed rows of the metal surface and that it can transit between two energetically equivalent extended and contracted conformations by overcoming a small energy barrier. 相似文献
39.
40.
D A Craig P M Colletti D Ratto J S Gordonson J K Raval O P Sharma 《Magnetic resonance imaging》1988,6(5):567-573
Postero-anterior radiographs and magnetic resonance imaging (MRI) of the chest were performed in nine biopsy proven cases of sarcoidosis. MRI was more sensitive than a postero-anterior chest roentgenogram in detecting hilar and mediastinal adenopathy but less informative in detecting pleural and parenchymal disease. 相似文献