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51.
C. Yohannan Panicker Hema Tresa Varghese Asha Raj K. Raju Tugba Ertan-Bolelli Ilkay Yildiz Ozlem Temiz-Arpaci Carlos M. Granadeiro Helena I.S. Nogueira 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):132-139
The FT-IR and FT-Raman spectra of 2-phenoxymethylbenzothiazole were recorded and analyzed. The surface enhanced Raman scattering (SERS) spectrum was recorded in a silver colloid. The vibrational wavenumbers of the compound have been computed using the Hartree–Fock/6-31G* basis and compared with the experimental values. The appearance of the Ag–O stretching mode at 237 cm−1 in the SERS spectrum along with theoretically calculated atomic charge density, leads us to suggest that the molecule is adsorbed through the oxygen atom with the molecular plane tilted on the colloidal silver surface. The direction of charge transfer contribution to SERS has been discussed from the frontier orbital theory. 相似文献
52.
Hypervalent‐Iodine(III)‐Mediated Oxidative Methodology for the Synthesis of Fused Triazoles 下载免费PDF全文
The organic chemistry of hypervalent organoiodine compounds has been an area of unprecedented development. This surge in interest in the use of hypervalent iodine compounds has mainly been owing to their highly selective oxidizing properties, environmentally benign character and commercial availability. Hypervalent iodine reagents have also been used as an alternative to toxic heavy metals, owing to their low toxicity and ease of handling. Hypervalent organoiodine(III) reagents are versatile oxidants that have been successfully employed to extend the scope of selective oxidative transformations of complex organic molecules in synthetic chemistry. This Focus Review concerns the tandem in situ generation and 1,5‐electrocyclization of N‐heteroaryl nitrilimines into fused triazoles. We describe the importance of recently developed hypervalent‐organoiodine(III)‐catalyzed oxidative cyclization reactions, building towards the conclusion that hypervalent iodine chemistry is a promising frontier for oxidative cyclization, in particular of hydrazones, for the synthesis of fused triazoles. 相似文献
53.
Synthesis of flower-like gold nanoparticles and their electrocatalytic activity towards the oxidation of methanol and the reduction of oxygen 总被引:1,自引:0,他引:1
This article describes the synthesis of branched flower-like gold (Au) nanocrystals and their electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Gold nanoflowers (GNFs) were obtained by a one-pot synthesis using N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid (HEPES) as a reducing/stabilizing agent. The GNFs have been characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical measurements. The UV-visible spectra show two bands corresponding to the transverse and longitudinal surface plasmon (SP) absorption at 532 and 720 nm, respectively, for the colloidal GNFs. The GNFs were self-assembled on a sol-gel-derived silicate network, which was preassembled on a polycrystalline Au electrode and used for electrocatalytic applications. The GNFs retain their morphology on the silicate network; the UV-visible diffuse reflectance spectra (DRS) of GNFs on the silicate network show longitudinal and transverse bands as in the case of colloidal GNFs. The GNFs show excellent electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Oxidation of methanol in alkaline solution was observed at approximately 0.245 V, which is much less positive than that on an unmodified polycrystalline gold electrode. Reduction of oxygen to H2O2 and the further reduction of H2O2 to water in neutral pH were observed at less negative potentials on the GNFs electrode. The electrocatalytic activity of GNFs is significantly higher than that of the spherically shaped citrate-stabilized Au nanoparticles (SGNs). 相似文献
54.
K. Suvardhan K. Suresh Kumar D. Rekha K. Kiran B. Jaya Raj P. Chiranjeevi 《Journal of Analytical Chemistry》2007,62(4):336-341
Newly synthesized 2-propylpiperidine-1-carbodithioate (2-PPC) was used for the extraction of Cr(III), Ni(II), and Zn(II) from
various water samples. In the present investigation, the use of a syringe loaded with sorbent for the separation and enrichment
of Cr(III), Ni(II), and Zn(II) prior to their determination by inductively coupled plasma-atomic emission spectrometry (ICP-AES)
was proposed to substitute the batch and column techniques. The described method was compared with the column technique with
respect to fastness, simplicity, recovery, and risk of contamination. The syringe was loaded with 1.0 g of sorbent in order
to retain the analyte elements. Next, 7.0 mL of sample solution (pH 5.0 ± 0.2) was drawn into the syringe in 15 s and discharged
over 15 s. Then, an eluent (3.0 M HCl) was drawn into the syringe and ejected back to desorb the analyte elements. At the
optimum conditions, the percentage recoveries of Cr(III), Ni(II), and Zn(II) were in the range of 94.50 to 99.62% with a standard
deviation (S.D.) of 0.03%. The elements could be concentrated by drawing and discharging several portions of sample successively
and eluting only one time. The detailed study of various interferences proved the method to be highly selective. The risk
of contamination is less than that with the column technique. The method was successfully applied to the determination of
Cr(III), Ni(II), and Zn(II) in spiked and natural water samples. The results obtained are in good agreement with those obtained
by the reported methods at the 95% confidence level.
The text was submitted by the authors in English. 相似文献
55.
Reaction of hexaamminecobalt(III) chloride with the silver salt of methanesulphonic acid in aqueous medium (1:3 molar ratio) forms hexaamminecobalt(III) methanesulphonate, [Co(NH3)6](CH3SO3)3, in high yield. This cobalt(III) complex has been characterized by spectroscopic techniques (UV/visible, IR and NMR) and its solubility product determined. The X-ray crystal structure shows that the [Co(NH3)6]3+ cations interact at the second sphere by sharing edges with the anions, via N–H O hydrogen bonds. The structure is related to that of [Co(NH3)6]Cl(CH3SO3)2, but is modified to accommodate additional anions in place of Cl−. 相似文献
56.
Verma Neha Sharma Vishal Kumar Raj Sharma R. Joshi M. C. Umapathy G. R. Ohja Sunil Chopra Sundeep 《Analytical and bioanalytical chemistry》2019,411(16):3477-3495
Analytical and Bioanalytical Chemistry - The detection of computer-generated document forgeries has always been a challenging task for forensic document examiners (FDE). With the aim to support the... 相似文献
57.
R. Malathi G. Anitha K. Anand Solomon G. Suresh S. S. Rajan S. Narasimhan J. Josepha Lourdu Raj Geetha Gopalakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):o70-o72
Nimbolide [systematic name: (4α,5α,6α,7α,15β,17α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,13,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], C27H30O7, was isolated from the leaves of Azadirachta indica, and its isomer, isonimbolide [systematic name: (4α,5α,6α,7α,15α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,16,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], was prepared from a novel rearrangement reaction of nimbolide, using boron trifluoride etherate and tetrabutylammonium bromide. The reaction conditions are probably responsible for the ether cleavage, double‐bond rearrangement and reformation of the ether linkage. As a result, there are conformational changes in two cyclopentane rings and the side‐chain –CH2COOMe group. In isonimbolide, an (24) hydrogen‐bond motif is observed. 相似文献
58.
Ram C. Maurya Dinesh C. Gupta Rajesh Shukla Raj K. Shukla Nalmas Anandam Mannar R. Maurya 《Transition Metal Chemistry》1986,11(12):463-464
Summary A new series of cyano-substituted nitrosylchromium(I) complexes having octahedral stereochemistry around the metal ion, and of general formula, [CrNO(CN)2(L)2(H2O)] (L =o-,m- andp-phenetidines oro-,m-, andp-anisidines) have been isolated in the solid state by interaction of potassium pentacy-anonitrosylchromate(I) monohydrate with the appropriately substituted aniline. The complexes, which have been characterised by elemental analysis, conductance, molecular weight determination, magnetic measurements, e.s.r. and i.r. spectral studies, contain chromium(I) in a low-spin d5-configuration. 相似文献
59.
Summary Novel bimetallic alkoxides of copper(II) of the type Cu[M(OPr-i)6]2 (M = Nb or Ta) have been synthesised by the interaction of CuCl2 (1 mol) with K[M(OPr-i)6] (2 mol). These bimetallic isopropoxides undergo facile alcohol interchange with primary alcohols such as MeOH, EtOH,n-PrOH andn-BuOH. However, witht-BuOH, the reaction cannot be driven to completion even under prolonged continuous azeotropic fractionation of the liberatedi-PrOH and the final product corresponded in analysis to Cu[Ta(OPr-i)2(OBu-t)4]2.I.r., electronic and electron spin resonance spectral and magnetic susceptibility measurements indicate a distorted octahedralD
4h geometry for copper(II) in these bimetallic alkoxides. 相似文献
60.
Raj K. Sehgal Sisir K. Sengupta R. Karl Dieter 《Journal of heterocyclic chemistry》1985,22(3):665-667
A single step synthesis of 2-deaminoactinomycin D ( 3a ) and 2-deamino-2-nitroactinomycin D ( 2a ) arising from actinomycin D ( 1a, AMD ) is reported. Structural confirmation was made by nmr, ir and chemical conversion to known materials. 相似文献