Combinatorial development of chiral phosphoramidite-ligands for enantioselective conjugate addition reactions

Chiral phosphoramidite ligands embodying bispidine frame work and a binaphthyl phosphoramidite for Cu-catalysed enantioselective conjugate addition reactions were developed employing principles of combinatorial and solid phase chemistry.     

Total synthesis of stevastelin B3

The total synthesis of stevastelin B3 was achieved using, as a key step, a method developed by us for the synthesis of 2-methyl-1,3-diols by Ti(III)-mediated diastereo- and regioselective opening of trisubstituted 2,3-epoxy alcohols, to carry out the stereoselective construction of its propionate-derived fatty acid segment.     

Magnetic susceptibility of ruthenium(III) in tris-ethylenediamine salts. Effect of outer sphere ligands

The paramagnetic susceptibility of Ru(III) in tris-ethylenediamine salts has been measured as a function of temperature. In all cases the iodide salt exhibits a greater susceptibility than the bromide salt. This difference may be attributed to a larger degree of temperature independent paramagnetism in the iodide complex due to the presence of low lying charge transfer states.     

Enhancement of photocatalytic activity and regeneration of Fe-doped TiO2 (Ti1−xFexO2) nanocrystalline particles synthesized using inexpensive TiO2 precursor

Research on Chemical Intermediates - Fe-doped TiO2, Ti1?xFexO2 (x?=?0.00, 0.01, 0.03, 0.05, 0.07, and 0.09) photocatalysts with enhanced activity were synthesized via a...     

Rayleigh flow of one-fluid plasma

The unsteady hydromagnetic flow of a one-fluid plasma confined between two infinitely large and infinitely separated magnetic pole-pieces in investigated. The resistive and ion-cyclotron terms are retained in the governing equations. The time-dependent motion is set up by the impulsive change in velocity of one of the pole-pieces. By means of Laplace transform technique, a solution is obtained which provides the smooth transition from zero to infinite conductivity of the plasma in addition to the effects of viscosity and the Hall current. The resulting two-dimensional flow is found to be permeated by hydromagnetic waves generated by the interaction of the skin-effect, Alfvén propagation and ion-cyclotron gyration. At the stages of motion the shearing stress at the pole-piece is found to be oscillatory.     

Influence of electric field on the hydrogen bond network of methanol

The understanding of the structure of hydrogen (H) bonding liquids in electric (E) fields is important in the context of several areas of research, such as electrochemistry, surface science, and thermodynamics of electrolyte solutions. We had earlier presented a general thermodynamic framework for this purpose, and had shown that the application of E field enhances H-bond interactions among water molecules. The present investigation with methanol suggests a different result-the H-bond structure, as indicated by the average number of H bonds per molecule, goes through a maxima with increasing field strength. This result is explained based on the symmetry in the location of the H-bonding sites in the two types of molecules.     

Reduction of spin diffusion artifacts from 2D zfr-INADEQUATE MAS NMR spectra

The primary shortcoming of the z-filtered refocused INADEQUATE MAS NMR pulse sequence is the possibility of artifacts introduced during the z-filter due to spin diffusion where by extra peaks in the single-quantum dimension (from other sites in the molecule) appear correlated with a given double-quantum frequency. This is a problem when the spinning speeds are too slow (less than 15 kHz) to sufficiently average the proton-proton homonuclear dipolar couplings. This would be especially important when working with large volume rotors that are difficult to spin fast enough to completely average the homonuclear couplings. In our experiments we used the frequency-switched Lee-Goldberg (FSLG) method of homonuclear decoupling during the z-filter to remove the artifact peaks. This method has the advantage of being quite easy to setup and implement on most modern NMR spectrometers.     

HPTLC Densitometric Quantification of Hydrolyzable Tannins from Triphala churna

JPC – Journal of Planar Chromatography – Modern TLC - A simple high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous quantification of...     

2,6-Diacylnaphthalene-1,8:4,5-bis(dicarboximides): synthesis, reduction potentials, and core extension

2,6-Diacyl derivatives of naphthalene-1,8:4,5-bis(dicarboximide)s have been synthesized via Stille coupling reactions of the corresponding 2,6-distannyl derivative with acyl halides. Reaction of these diketones with hydrazine gave phthalazino[6,7,8,1-lmna]pyridazino[5,4,3-gh][3,8]phenanthroline-5,11(4H,10H)-dione fused-ring derivatives. The products were characterized by UV-vis absorption spectroscopy and electrochemistry, modeled using density functional theory calculations, and, in some cases, studied and compared using single-crystal X-ray diffraction.