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131.
132.
P. Srihari Dinesh C. Bhunia P. Sreedhar S.S. Mandal J. Shyam Sunder Reddy J.S. Yadav 《Tetrahedron letters》2007,48(46):8120-8124
Aryl propargylic methanols undergo C- and O-nucleophilic substitution reactions in the presence of a catalytic amount of iodine in short reaction times with good yields. 相似文献
133.
G. Dinesh Kumar Dr. Marzena Banasiewicz Prof. Denis Jacquemin Prof. Daniel T. Gryko 《化学:亚洲杂志》2021,16(4):355-362
For the first time diketopyrrolopyrroles (DPPs) have been synthesized directly from nitriles possessing (aza)crown ethers leading to macrocycle-dye hybrids. Depending on the nature of the linkage between DPP and macrocyclic ring, various coordination effects are found. The strong interaction of the cations possessing Lewis acid character such as Li+, Mg2+ and Zn2+ with 2-aminopyridin-4-yl-DPPs, leading to a bathochromic shift of both emission and absorption, as well as to strong enhancement of fluorescence was rationalized in terms of strong binding of these cations to the N=C−NR2 functionality. The same effect has been observed for protonation. Depending on the size and the structure of the macrocyclic ring the complexation of cations by aza-crown ethers plays an important but secondary role. The interaction of Na+ and K+ with 2-aminopyridin-4-yl-DPPs leads to moderate enhancement of fluorescence due to the aza-crown ethers binding. The very weak fluorescence of DPP bearing 2-dialkylamino-pyridine-4-yl substituents is due to the closely lying T2 state and the resulting intersystem crossing. 相似文献
134.
135.
The kinetics of the oxidative degradation of d -fructose by nanoparticles of MnO2 has been studied in dilute sulfuric acid medium and also in the presence of surfactants of cetyl trimethyl ammonium bromide (CTAB), Triton X-100 (TX-100), and Tween 20. Amorphous nanoparticles of MnO2 in the form of spherical particulates of size 50–200 nm, as detected by a transmission electron microscope, have been found to exist, supported on two-dimensional gum acacia sheets. The reaction is first order in MnO2 but complex order with respect to fructose and H+. The reaction is inhibited due to adsorption of reaction products on the surface of MnO2 nanoparticles. The reaction takes place through an intermediate complex formation between β-d -fructopyranose and protonated MnO2. A one-step two-electron transfer reaction ultimately leads to the formation of an aldonic acid and formic acid. The entropy of activation plays the key role for the reaction in the absence of surfactants. In the surfactant-mediated reaction, partitioning of both the reactants takes place between the aqueous and micellar pseudophases and reaction occurs following Berezin's model. Binding of fructose with the surfactants in the Stern/palisade layer takes place through the ion–dipole interaction and H-bonding while protonated MnO2 remains at the outer side of the Stern/palisade layer within the micelle. Both the enthalpy and entropy changes associated with the fructose–water interaction, fructose–micelle interaction, and micelle–water interaction finally control the fructose–micelle binding. 相似文献
136.
A green synthesis of 1,2,3-triazolyl-pyridine hybrids and evaluation of their antibacterial activity
137.
In a non-aqueous medium, oxidation kinetics of thioglycolic, thiolactic and thiomalic acids by benzimidazolium dichromate have been studied. In the temperature range of 20°C–50°C, oxidation kinetics were examined by spectrophotometry. In terms of oxidant, the reaction is dependent on the unitary order. In the case of thioacids, we find the Michaelis-Menten type kinetics. Hydrogen-ions act as catalyst in this process. The reaction rate slows down as the Mn2+ ion concentration increases. The reaction does not cause acrylonitrile to polymerize. The formation of a thioester into the pre-equilibrium followed by its progressive degradation was postulated as a mechanism. 相似文献
138.
Pressure-induced structural aspects and elastic properties of NaCl-type (B1) to CsCl-type (B2) structure in praseodymium chalcogenides and pnictides are presented. Ground-state properties are numerically computed by considering long-range Coulomb interactions, Hafemeister and Flygare type short-range overlap repulsion, and van der Waals interaction in the interionic potential. From the elastic constants, Poisson's ratio ν, the ratio RG/B of G (shear modulus) over B (bulk modulus), anisotropy parameter, shear and Young's moduli, Lamé's constant, Kleinman parameter, elastic wave velocity and thermodynamical property such as Debye temperature are calculated. Poisson's ratio ν and the ratio RG/B indicate that PrX and PrY are brittle in B1 phase and ductile in B2 phase. To our knowledge, this is the first quantitative theoretical prediction of the ductile (brittle) nature of praseodymium chalcogenides and pnictides and still awaits experimental confirmation. 相似文献
139.
Ram N. Patel Anurag Singh Krishna K. Shukla Dinesh K. Patel Vishnu P. Sondhiya 《Transition Metal Chemistry》2010,35(5):577-584
Abstract
Two new copper(II) complexes, [Cu(Hhida)(BenzImH)]·H2O (1) and [Cu(Hhida)(EtImH)]·2H2O (2) have been synthesized by the interaction of basic copper carbonate with N-(2-hydroxyethyl)-2-aminodiacetic acid (Hhida2−) and benzimidazole (BenzImH) or (2-ethylimidazole (EtImH)). The structures of both complexes were studied by single crystal X-ray diffraction. The geometry around the copper(II) atom can be best described as distorted square pyramidal as indicated by the value of the trigonal index τ = 0.32 for (1) and 0.21 for (2). Spectroscopic and electrochemical studies were performed in order to correlate structural features of the complexes with their superoxide scavenger activity. The ability of the complexes to scavenge superoxide anions was also evaluated. 相似文献140.
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