The present article describes the synthesis, spectral, coordination and thermal aspects of N,N′-polymethylene bis(1-phenyl-3-methyl-4-trifluoroacetylimino-2-pyrazoline-5-ol)oxovanadium(IV) or copper(II) Schiff base complexes with alkyl
backbones ranging from two to four carbons have been characterized on the basis of elemental analysis, magnetic moments, molar
conductivity measurements, spectra (FTIR, ESR, UV-Visible, MS), VPO and thermal studies. The vapour pressure osmometry (VPO)
and mass spectral studies indicate that the complexes are monomeric. An ESR study of all these complexes of VO(IV) and Cu(II)
are consistent with the square pyramidal and square planar geometries of these metal ions, respectively. In addition, the
kinetics and thermodynamic parameters for the different thermal decomposition steps of the complexes have been studied employing
Horowitz-Metzger and Freemen-Carroll methods. 相似文献
A selective, precise, and accurate high-performance thin-layer chromatographic (HPTLC) method has been developed for the analysis of L-dopa in Mucuna pruriens seed extract and its formulations. The method involves densitometric evaluation of L-dopa after resolving it by HPTLC on silica gel plates with n-butanol-acetic acid-water (4.0+1.0+1.0, v/v) as the mobile phase. Densitometric analysis of L-dopa was carried out in the absorbance mode at 280 nm. The relationship between the concentration of L-dopa and corresponding peak areas was found to be linear in the range of 100 to 1200 ng/spot. The method was validated for precision (inter and intraday), repeatability, and accuracy. Mean recovery was 100.30%. The relative standard deviation (RSD) values of the precision were found to be in the range 0.64-1.52%. In conclusion, the proposed TLC method was found to be precise, specific and accurate and can be used for identification and quantitative determination of L-dopa in herbal extract and its formulations. 相似文献
Transition metal [M = VO (IV) and/or Cu (II)] complexes with Schiff base ligand, (Z)‐2‐((2‐hydroxybenzylideneamino)phenol (H2L) have been entrapped in the super cages of zeolite‐Y by Flexible Ligand Method. Synthesized materials have been characterized by preferential physico‐chemical techniques such as inductively coupled plasma optical emission spectroscopy (ICP‐OES), elemental analyses (CHN), fourier transmission infrared spectroscopy (FTIR), electronic and UV‐reflectance spectra, Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron micrographs (SEMs), X‐ray diffraction patterns (XRD) and thermogravimetric analysis (TGA). The catalytic competence of zeolite‐Y entrapped transition metal complexes was examined in Baeyer‐Villiger (BV) oxidation of cyclopentanone using 30% H2O2 as an oxidant beside neat complexes to check the aptitude of heterogeneous catalysis over the homogeneous system. The effect of experimental variables such as mole ratio of substrate to an oxidant, amount of catalyst, reaction time, varying oxidants and solvents on the conversion of cyclopentanone was also tested. Under the optimized reaction conditions, one of the zeolite‐Y entrapped transition metal complex viz. [VO(L)H2O]‐Y [where L = (Z)‐2‐((2‐hydroxybenzylideneamino)phenol] was found to be a potential contender by providing 80.22% conversion of cyclopentanone (TON: 10479.42), and the selectivity towards δ‐valerolactone was 83.56%. 相似文献
A pyrene functionalized oxacalix[4]arene architecture (DPOC) was utilized as a fluorescence probe for selective recognition of cyanide ions. The receptor DPOC shows excellent selectivity towards cyanide ion with a red shift of 108 nm in absorption band along with a significant change in colour from light yellow to pink. The fluorescence titration experiments further confirm the lower limit of detection as 1.7µM with no significant influences of competing anions. 1 H-NMR titration experiments support the deprotonation phenomena, as the -NH proton disappears upon successive addition of cyanide ions. The DFT calculation also indicates a certain increment of -NH bond length upon interaction with cyanide ions. The spectral properties as well as colour of DPOC-CN? system may be reversed upon the addition of Ag+/ Cu2+ ions up to 5 consecutive cycles. Moreover, DPOC coated “test strips” were prepared for visual detection of cyanide ions.
SESAME (Synchrotron Light for Experimental Science and Applications in the Middle East) is an international synchrotron radiation project under the auspices of UNESCO. The physical site is located in Amman, Jordan. At press time, the building was scheduled for completion by March 2007. 相似文献
A direct and efficient route for the construction of racemic and optically active L-telluromethionine (L-Te-Met) starting from the readily available hydrochloride salt of α-amino-γ-butyrolactone and lithium methyltellurolate is described. The reaction has been successfully scaled up to afford gram quantities of L-Te-Met in 75–80% yield. 相似文献
Fluorescence properties of five 4-acyl pyrazolone based hydrazides (H2SBn) and their Fe (III) heterochelates of the type [Fe(SBn)(L)(H2O)]·mH2O [H2SBn = nicotinic acid [1-(3-methyl-5-oxo-1-phenyl-4,5-di hydro-1H-pyrazol-4yl)-acylidene]-hydrazide; where acyl = –CH3, m = 4 (H2SB1); –C6H5, m = 2 (H2SB2); –CH2–CH3, m = 3 (H2SB3); –CH2–CH2–CH3, m = 1.5 (H2SB4); –CH2–C6H5, m = 1.5 (H2SB5) and HL = 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid] were studied at room temperature. The fluorescence spectra of heterochelates show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (S*), pre-exponential factor (A), enthalpy (H*) and Gibbs free energy (G*) have been reported. 相似文献