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21.
Ghosh SK Khatua PK Ghosh JK Bhattacharya SC 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(3):395-401
This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu2+, Co2+, Ni2+ and Mn2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal. 相似文献
22.
Borrowing hydrogen from alcohols, storing it on a catalyst and subsequent transfer of the hydrogen from the catalyst to an in situ generated imine is the hallmark of a transition metal mediated catalytic N-alkylation of amines. However, such a borrowing hydrogen mechanism with a transition metal free catalytic system which stores hydrogen molecules in the catalyst backbone is yet to be established. Herein, we demonstrate that a phenalenyl ligand can imitate the role of transition metals in storing and transferring hydrogen molecules leading to borrowing hydrogen mediated alkylation of anilines by alcohols including a wide range of substrate scope. A close inspection of the mechanistic pathway by characterizing several intermediates through various spectroscopic techniques, deuterium labelling experiments, and DFT study concluded that the phenalenyl radical based backbone sequentially adds H+, H˙ and an electron through a dearomatization process which are subsequently used as reducing equivalents to the C–N double bond in a catalytic fashion.An efficient method is developed for harvesting hydrogen, its storage and catalytic transfer by an odd alternant hydrocarbon. The strategy is reminiscent of transition metals in borrowing hydrogen mediated processes. 相似文献
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Shuvendu S. Bhattacharyya Bandana Mandal A. K. Das 《Fresenius' Journal of Analytical Chemistry》1996,355(2):180-182
An electrothermal atomic absorption spectrometric method is described for the determination of manganese in various coal fly ash samples after its separation with dissolved monothioxo--diketone as chelating ion exchanger. The detection limit is 1 ngml-1. To study the accuracy of the method, a reference material of similar composition was analysed and recovery of spiked manganese was performed. 相似文献
29.
Powder X-ray diffraction (XRD) and Raman spectroscopic study of order-disorder-phase transition with increase in the content of Gd in Nd2−yGdyZr2O7 solid solution is being reported. It has been observed from Rietveld analysis that with increase in concentration of Gd in Nd2−yGdyZr2O7, the value of the x parameter of the 48f oxygen changes from 0.332(1) to 0.343(1) with a sudden change in the slope for y=1.8, which indicates that the structure is transforming from ordered pyrochlore to disordered pyrochlore. In addition to that a sudden and drastic change in the Raman spectra including changes in the position and width of several Raman modes beyond y?1.8 has also been observed which has been correlated with increasing disorder. Based on these studies, it is suggested that there is a discontinuous order-disorder transition from ‘perfect pyrochlore’ to ‘defect pyrochlore’ phase in Nd2−yGdyZr2O7 solid solution. 相似文献
30.
Syntheses of Boc-protected 4-amino- and 5-amino-pyrrole-2-carboxylic acid methyl esters have been achieved and the structures of these compounds have been fully characterized by detailed NMR studies. 相似文献