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21.
One-pot, three-component synthesis of spiro[diindenopyridine-indoline]triones has been reported via the reaction of 1,3-indandione, aromatic amines, and isatins with (PEG-OSO3H) as an efficient, polymeric acid surfactant–based catalyst in water and also in presence of acidic ionic liquid [NMP]H2PO4, which acts both as a medium and catalyst under conventional heating and ultrasonic irradiation. The reactions were complete in short reaction times with excellent yield of products. Surfactant-based PEG-OSO3H could be recycled and reused several times without any significant loss of activity. The compounds exhibit fluorescence in methanol with large Stokes shift. 相似文献
22.
Vijay Nair Sreeletha B. Panicker Sindhu Mathai 《Research on Chemical Intermediates》2003,29(2):227-231
The bromination of cyclopropanes using potassium bromide and cerium(IV) ammonium nitrate (CAN) in a two-phase system consisting of water and dichloromethane affording 1,3-dibromides in excellent yields is reported. 相似文献
23.
An electrochemical creatinine sensor based on a molecularly imprinted polymer (MIP)‐modified sol‐gel film on graphite electrode was developed. The surface coating of MIP over sol‐gel was advantageous to obtain a porous film with outwardly exposed MIP cavities for unhindered selective rebinding of creatinine from aqueous and biological samples. A fast differential pulse, cathodic stripping voltammetric response of creatinine can be obtained after being preanodized the sensor in neutral medium containing appropriate amount of creatinine at +1.8 V versus SCE for 120 s. A linear response over creatinine concentration in the range of 1.23 to 100 μg mL?1 was exhibited with a detection limit of 0.37 μg mL?1 (S/N=3). 相似文献
24.
The development of an easy-to-use, rapid, robust and inexpensive technique is required which can measure the basal concentration of uric acid (UA) lower than 1.0 x 10(-7)M ( approximately 0.017 mgL(-1)) in biological samples to attend the problem of hypouricemia. In the present work an artificial receptor for UA, silica gel-bonded molecularly imprinted polymer (MIP), was used as a sorbent for molecularly imprinted solid-phase extraction (MISPE) in column chromatography. The use of a sensor based on a MIP-modified hanging mercury drop electrode (HMDE), as reported from our laboratory, could estimate UA with detection limit as low as 0.024 mgL(-1) under the optimized conditions of differential pulse, cathodic stripping voltammetric (DPCSV) measurement. However, in the current investigation, with the use of the combination of MISPE followed by detection with a MIP-based HMDE sensor, the minimum detectable concentration could go down to 0.0008 mgL(-1) (RSD=0.63%, S/N=3). The same MIP receptor for both MISPE and the corresponding sensor was able to enhance the preconcentration of analyte substantially so as to attain the desired level of sensitivity; and that to without any interference (cross-reactivity) from other structurally related analogues including the major interferent like ascorbic acid prevalent in the aqueous environment of biological samples. 相似文献
25.
M. S. Sujamol Y. Sindhu C. J. Athira K. Mohanan 《Russian Journal of Inorganic Chemistry》2011,56(8):1276-1283
An azo derivative was synthesized by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with 2-naphthol and this
new ligand formed a series of metal complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) salts. These complexes were characterized
on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-Visible, IR and 1H NMR spectral data. Analytical data revealed that all the complexes exhibited 1: 1 metal-ligand ratio. Spectral studies showed
that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated
to the metal ion in a tridentate fashion. On the basis of electronic spectral data and magnetic susceptibility measurements,
suitable geometry was proposed for each complex. The ligand and its cobalt(II) complex were subjected to X-ray diffraction
study. The thermal behaviour of the ligand and its copper(II) complex was examined by thermogravimetry. The ligand and its
copper(II) and nickel(II) complexes were applied to silk fabric and their fastness properties were evaluated. 相似文献
26.
Metal complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) with a Schiff base derived from isatin and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene were synthesised and characterised by elemental analysis, conductance measurements, magnetic susceptibility, UV-Vis, IR, 1H NMR and EPR spectral studies. The spectral data revealed that the ligand acted as a neutral tridentate, coordinating to the metal ion through the azomethine nitrogen, ester carbonyl and carbonyl oxygen of the isatin moiety. The EPR spectral data indicated that metal-ligand bonds have considerable covalent character. The copper(II) complex was subjected to X-ray diffraction and cyclic voltammetric studies. The ligand and the metal complexes were screened for their antibacterial activity and it has been observed that the metal complexes are more potent bactericides than the ligand. 相似文献
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29.
Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in
strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in gadolinium.
The higher order elastic constants are used to find out the generalized Gruneisen parameters of the elastic waves propagating
in different directions in gadolinium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma
is obtained. The results are compared with the available reported values. 相似文献
30.
R. S. Sindhu Dr. K. B. Pandeya R. P. Singh 《Monatshefte für Chemie / Chemical Monthly》1977,108(2):361-366
Complex formation of indium(III) with three disubstituted pyridines, viz., 2,3-dihydroxypyridine, 2-amino-3-hydroxypyridine and 3-hydroxypyridine-2-thiol has been studied polarographically (=0.1; temp.=25±0.1°C). All the systems show reversible electrode behaviour.DeFord andHume method as modified byIrving has been applied for determining composition and stability constants. Distribution of different species as a function of ligand concentration has been calculated and shown graphically.With 4 Figures 相似文献