Spectral investigation of the effect of anion on the stability of non covalent assemblies of 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecine (benzo-15-crown-5) with sodium halides.

A series of complexes of 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecine (benzo-15-crown-5) with sodium halides was synthesized in acetonitrile. The effect of anion on the stability and spectral properties of complexes of benzo-15-crown-5 with sodium halides was investigated. The synthesis of complexes of sodium fluoride and sodium chloride are reported for the first time. Chloroform was used as solvent to study the assembly in solution state by 1H and 13C NMR techniques. Single crystal diffraction studies on the easily crystallizable bromide complex confirmed 1:1 stoichiometry of the complex. IR and Raman studies provided valuable evidence for a water molecule shared between the crown encapsulated cation and the counter ion to give a solvent shared ion pair (SSIP). The fluorescence spectra of the complexes were obtained in chloroform by excitation at 270nm to study the effect of complexation on the fluorescent properties of benzo-15-crown-5.

Solvatochromic and single crystal studies of 3-(4-bromophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde.

The structure of 3-(4-bromophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde was determined by using X-ray diffraction analysis. Photophysical studies of the title compound were investigated in the solvents with different polarities. The emission spectrum of the compound was recorded in polar solvent DMSO (356 nm). In different solvents the extinction coefficients and quantum yield of the compound vary from 1.88×10(4) to 3.53×10(4) and 0.01 to 0.25, respectively. The ratio of the dipole moment of excited state to the dipole moment of ground state was calculated by using solvatochromic shift methods.

High-performance liquid chromatography analysis of plant saponins: An update 2005-2010.

Saponins are widely distributed in plant kingdom. In view of their wide range of biological activities and occurrence as complex mixtures, saponins have been purified and separated by high-performance liquid chromatography using reverse-phase columns at lower wavelength. Mostly, saponins are not detected by ultraviolet detector due to lack of chromophores. Electrospray ionization mass spectrometry, diode array detector , evaporative light scattering detection, and charged aerosols have been used for overcoming the detection problem of saponins.

RP-HPLC analysis and antidiabetic activity of Swertia paniculata.

1,2,6,8-Tetrahydroxyxanthone (SR1) and 2,8-dihydroxy-1,6-dimethoxyxanthone (SR2) have been qualitatively and quantitatively determined in leaves and rhizomes of Swertia paniculata. The methanol extracts were analyzed on a C18 column using MeOH and H20 as mobile phase at a flow rate of 1 mL/min. Identification was achieved using an UV variable lambda detector set at 260 nm. Variation in the bioactive compounds with respect to season and altitude was determined, along with the examination of the antidiabetic activity of the plant. The maximum concentration of SR1 and SR2 was found in leaves collected from Tungnath (3600 m), Uttarakhand, India, in October. The blood sugar level in alloxan induced rats was decreased by 51.0% by the methanol extract of the leaves. Overall, results showed that the concentration of bioactive compounds increased with altitude. October was the period of prime potency and should be the time of harvest for S. paniculata.