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81.
N,N'-Dipicolyl, bis(stilbylvinylpyridylmethyl), and diquinaldyl methionine derivatives form stable Cu(II) complexes with metal ligation by three nitrogen atoms and the carboxylate. One-electron reduction results in the exchange of carboxylate for sulfide in the complexes. This ligand reorganization is accompanied by inversion of the helical orientation of the two arms containing nitrogen heterocycles, resulting in nearly mirror image circular dichroism spectra. This paper provides details for the synthesis of these complexes and the evidence for the remarkable stereochemical interconversion that accompanies the reduction reaction. Detailed analysis of the electronic spectra of the ligands and metal complexes is provided along with X-ray crystallographic structures of Cu(II) and Zn(II) complexes of the N,N'-dipicolylmethionine complexes. 相似文献
82.
The facile cross-coupling reactivity of triarylbismuth compounds with aryl iodides was achieved under mild heating conditions. The established catalytic protocol using Pd(OAc)2(Cy2NH)2 system exhibited high coupling reactivity with a variety of triarylbismuth and aryl iodide compounds under mild conditions. These coupling reactions were completed in short reaction time affording good to high yields of functionalized biaryl products. The studies of multi-coupling reactions with tris(4-iodophenyl)amine, 8 also furnished moderate to good yields of coupled products, 8a-8f. 相似文献
83.
84.
An indirect method for the determination of vanadium as vanadate by atomic absorption spectrometry is described. In neutral medium, vanadate forms a stable ion-association complex with copper (II) and biguanide, which is extractable into butanol with an efficiency higher than 99%. The copper content in the extract (and hence indirectly VO?3) is determined by aspirating it directly into an acetylene flame. The calibration graph is linear up to 3.4 μg ml?1 of VO?3. The limit of detection is 16 ng ml?1. Only chromium interferes. 相似文献
85.
Tanmay Chattopadhyay Manami Ghosh Arpita Banerjee Kazi Sabnam Banu Debasis Das Munirathinam Nethaji 《Transition Metal Chemistry》2007,32(4):531-535
Linkage isomers trans-bis(N-propyl-1,2-diaminoethane)dinitronickel(II) (brown, 1), trans-bis(N-isopropyl-1,2-diaminoethane)dinitritonickel(II) (blue-violet, 2a) and trans-bis(N-isopropyl-1,2-diaminoethane)dinitronickel(II) (brown, 2b) have been synthesized from solution and X-ray single crystal structure analysis of complex (1) has been performed. Simultaneous TG-DTA analyses reveal that complex (1) exhibits two successive phase transitions before to undergo decomposition (initial temperature of decomposition, Ti = 215
°C). The first one is reversible (82–98 °C; ΔH = 1.75 kJ mol−1 for heating and 93–77 °C; ΔH = −1.65 kJ mol−1 for cooling) and the second one is irreversible endothermic (135–150 °C kJ mol−1; ΔH = 1.80 kJ mol−1) phase transition. No visual color changes are observed in any of the two transitions. The causes related to the first phase
transition remain unexplored. However, on the basis of IR spectral studies the second phase transition is supposed to be due
to conformational changes of the diamine chelate rings. On the other hand, complexes (2a) and (2b) undergo decomposition without showing any phase transition [Ti = 185 and 195 °C for (2a) and (2b), respectively]. 相似文献
86.
Debasish Banerjee Bhim C. Mondal Debasis Das Arabinda K. Das 《Mikrochimica acta》2003,141(3-4):107-113
A new resin has been synthesized by functionalisation of polystyrene-divinylbenzene (8%) with imidazole 4,5-dicarboxylic
acid through –N=N– bonding. The resulting resin has been characterised by elemental analysis, thermogravimetric analysis,
infrared spectroscopy, hydrogen ion capacity and metal ion capacity. The speciation study of vanadium has been studied by
using this resin and the maximum exchange capacity was found to be 0.45 mmol g−1 for V4+ and that for V5+ was 1.57 mmol g−1 at pH 3 for both. The eluents malonic acid and sodium hydroxide have been used for the selective separation of vanadium(IV)
and vanadium(V) species respectively. The effects of diverse ions on the sorption and recovery of each species have been studied.
Finally, the developed method has been applied for the speciation and determination of these two species in natural water
samples.
Correspondence: Department of Chemistry, The University of Burdwan, Burdwan, India. e-mail: akdas100@yahoo.com
Received December 20, 2001; accepted October 11, 2002 相似文献
87.
88.
Transport in Porous Media - In this paper, an approximate integral equation solution for a horizontal, unsteady flow of two viscous incompressible fluids is derived. Wettability variation of the... 相似文献
89.
Santanu Mandal Ashok Kumar Rout Guillaume Pilet Debasis Bandyopadhyay 《Transition Metal Chemistry》2009,34(7):719-724
Two new mononuclear complexes of copper(II), namely [CuL2] (1) and [CuL′2] (2) have been synthesized by reacting copper perchlorate with furfurylamine and salicylaldehyde or 2-hydroxyacetophenone, where
L = (2-hydroxybenzyl-2-furylmethyl)imine and L′ = (2-hydroxymethylbenzyl-2-furylmethyl)imine, the respective asymmetric bidentate
Schiff bases that are formed in situ to bind the Cu(II) ion. The complexes have been characterized by elemental analysis,
IR spectroscopy and single crystal X-ray diffraction studies. Structural studies reveal that the mononuclear units of both
the complexes (1) and (2) adopt square planar geometry supported by weak intermolecular C–H···π interactions. 相似文献
90.
A polystyrene divinyl benzene (8%) copolymer has been functionalized by coupling it through NN group with 2-naphthol-3,6-disulfonic acid (NDSA). The resulting resin has been characterized by elemental analysis, thermogravimetric analysis and infrared spectra. The hydrogen ion, water regain and metal ion capacities of the resin have been determined. Two forms of chromium show different exchange capacities at different pH values, viz. Cr(III) selectively retained at pH 6.5 whereas Cr(VI) retained at pH 1.5. Hence complete separation of the two forms of chromium is possible. The kinetic studies show that the exchange of Cr(III) and Cr(VI) follows second-order kinetics. The metal ion concentration was measured by flame atomic absorption spectrometry. The method has been successfully applied for the speciation of chromium in natural water samples. 相似文献