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41.
K.?Jayalakshmi M.?Mahendra Basappa B.H.?Doreswamy M.A.?Sridhar J.?Shashidhara?Prasad K.S.?RangappaEmail author 《Journal of chemical crystallography》2005,35(1):67-70
The title compound (C22H19NOS) was synthesized, characterized and structure was determined by X-ray diffraction method. It crystallizes in the monoclinic space group P21/c with cell parameters a = 22.181(2) Å, b = 6.0760(4) Å, c = 13.349(3) Å, = 95.615(3)^, and {Z = 4}. The final residual factor is 0.0625 for 1724 reflections with I > 2(I). 4-thiazolidinone ring moiety shows twisted conformation. 相似文献
42.
A. Manohar V. Venkatachalam K. Ramalingam S. Thirumaran G. Bocelli A. Cantoni 《Journal of chemical crystallography》1998,28(12):861-866
Synthesis, spectral, and single crystal X-ray structural studies on (2,2-bipyridyl)bis (dimethyldithiocarbamato)zinc(II) (1) and (l,10-phenanthroline)bis(dimethyldithiocarbamato)zinc(II) (2) complexes are reported in this paper. The complex (1) crystallizes in the orthorhombic lattice, space group Pcca, a = 18.456(3), b = 6.529(2), and c = 17.092(2) Å. The complex (2) crystallizes in the monoclinic space group C2/c, a = 13.372(2), b = 13.850(2), c = 24.680(3) Å, and = 102.71(4)°. IR spectra of the complexes (1) and (2) show the thioureide (C-N) bands at 1489 and 1510 cm–1, respectively, which are lower than the value observed for the parent bisdithiocarbamate. Reduction in the thioureide stretching frequency is due to the increase in coordination around the zinc ion and the resultant increase in electron density. Thermal studies indicate that the 1,10-phenanthroline adduct is marginally more stable than the other complex. X-ray crystal structures of the two adducts show them to be octahedrally coordinated and monomeric in nature. The Zn-S distances are longer than those observed in the parent bisdithiocarbamate. The thioureide C-N bond distances in (1) and in (2) indicate the partial double bond character. The most important structural changes as a result of the adduct formation are observed in the Zn-S bond distances and S-Zn-S bond angles, in terms of very significant increases in Zn-S bond distances and reductions in S-Zn-S angles, compared to the parent bisdithiocarbamate. The observed changes are indicative of a strong steric force in operation in the adducts rather than electronic effects. 相似文献
43.
Jayalakshmi V Rama Krishna N 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,168(1):36-45
We describe an intensity-restrained optimization procedure for refining approximate structures of ligands within the protein binding pockets using STD-NMR intensity data on reversibly forming weak complexes. In this approach, the global minimum for the bound-ligand conformation is obtained by a hybrid structure refinement method involving CORCEMA calculation of intensities and simulated annealing optimization of torsion angles of the bound ligand using STD-NMR intensities as experimental constraints and the NOE R-factor as the pseudo-energy function to be minimized. This method is illustrated using simulated STD data sets for typical carbohydrate and peptide ligands. Our procedure also allows for the optimization of side chain torsion angles of protein residues within the binding pocket. This procedure is useful in refining and improving initial models based on crystallography or computer docking or other algorithms to generate models for the bound ligand (e.g., a lead compound) within the protein binding pocket compatible with solution STD-NMR data. This method may facilitate structure-based drug design efforts. 相似文献
44.
45.
Madhuresh K. Sethi Somashekar R. Bhandya Nagaraj Maddur Rohit Shukla Anish Kumar V.S.N. Jayalakshmi Mittapalli 《Tetrahedron: Asymmetry》2013,24(7):374-379
A novel chemo-enzymatic synthesis of (S)-rivastigmine using ketoreductases with NADH/NADPH as the proton donor has been demonstrated. An exclusive enzymatic process has been developed by exploring the possible ketoreductases by screening to identify enzymes useful for the preparation of the (S)-isomer intermediate, and scaling up of the enzymatic process for the production of an adequate, enantiomerically pure precursor of rivastigmine and for the total synthesis of (S)-rivastigmine. 相似文献
46.
The novel TiO2 nanopartilces/nanowires (TNPWs) composite with ZrO2 nanoparticles (ZNPs) shell-coated photoanodes were prepared to fabricate high-performance dye-sensitized solar cell (DSSC) based on different types of electrolytes. Hafnium oxide (HfO2) is a new and efficient blocking layer material applied over the TNPWs-ZNPs core-shell photoanode film. TiO2 nanoparticles (TNPs) and TiO2 nanowires (TNWs) were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). DSSCs were fabricated using the novel photoanodes with an organic sensitizer D149 dye and different types of electrolytes namely liquid electrolyte, ionic liquid electrolyte, solid-state electrolyte, and quasi-solid-state electrolyte. The DSSC-4 made through the novel core-shell photoanode using quasi-solid-state electrolyte showed better photocurrent efficiency (PCE) as compared to the other DSSCs. It has such photocurrent-voltage characteristics: short circuit photocurrent (Jsc)?=?19 mA/cm2, the open circuit voltage (Voc)?=?650 mV, fill factor (FF)?=?65 %, and PCE (η)?=?8.03 %. The improved performance of DSSC-4 is ascribed to the core-shell with blocking layer photoanode could increased electron transport and suppressed recombination of charge carriers at the TNPWs-ZNPs/dye/electrolyte interface. 相似文献
47.
S. Vijayalaxmi P. Prakash S. K. Jayalakshmi V. H. Mulimani K. Sreeramulu 《Applied biochemistry and biotechnology》2013,171(2):382-395
The alkaliphilic Bacillus halodurans strain PPKS-2 was shown to produce extracellular extreme alkaliphilic, halotolerent, detergent, and thermostable mannanase activity. The cultural conditions for the maximum enzyme production were optimized with respect to pH, temperature, NaCl, and inexpensive agro wastes as substrates. Mannanase production was enhanced more than 4-fold in the presence of 1 % defatted copra meal and 0.5 % peptone or feather hydrolysate at pH 11 and 40 °C. Mannanase was purified to 10.3-fold with 34.6 % yield by ion exchange and gel filtration chromatography methods. Its molecular mass was estimated to be 22 kDa by SDS-PAGE. The mannanase had maximal activity at pH 11 and 70 °C. This enzyme was active over a broad range of NaCl (0–16 %) and thermostable retaining 100 % of the original activity at 70 °C for 3 h. Immobilization of whole cells proved to be effective for continuous production of mannanase. Since the strain PPKS-2 grows on cheaper agro wastes such as defatted copra meal, corn husk, jowar bagasse, and wheat bran, these can be exploited for mannanase production on an industrial scale. 相似文献
48.
Neelamegan Haridharan Venkatachalam Ramkumar Raghavachari Dhamodharan 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):918-926
A novel initiator containing pyrene, a fluorescent moiety, was prepared by reacting 1-aminopyrene and 2-bromoisobutyl bromide. The structure elucidation of the new initiator was carried out using various spectroscopic tools, as well as through single crystal X-ray diffraction studies. Novel, fluorescent amphiphilic block copolymers with a pyrene end-group, poly(styrene-b-acrylic acid) [P(S-b-AA)], poly(methyl methacrylate-b-dimethylaminoethyl methacrylate) [P(MMA-b-DMAEMA)], poly(styrene-b-tert-butyl acrylate) [P(S-b?t-BA)], poly(styrene-b-dimethylaminoethyl methacrylate) [P(S-b-DMAEMA)] were successfully synthesized by the atom transfer radical polymerization (ATRP) method, using CuBr as the catalyst and N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/N,N,N′,N″,N″-hexamethyltriethylenetetramine (HMTETA) as the complexing agent. The polymers were characterized by GPC, 1H-NMR, IR and UV-Vis spectroscopies. It was observed that as the polymerization time increased, both the conversion and the molecular weight increased linearly with time. The fluorescence properties of the polymers prepared were recorded. The physical properties and especially the pH dependent swelling properties of the amphiphilic block copolymers have been investigated. The utility of the block copolymers in the formation of stable dispersion of cadmium sulphide nanoparticles was investigated as a model study. 相似文献
49.
Several substituted terphenyl derivatives were prepared following two synthetic routes with five steps. Condensation of 4‐amino‐3‐bromo‐benzotrifluoride with 4‐(methylthio) phenyl boronic acid in the presence of sodium carbonate and palladium triphenylphosphine in toluene gave 4‐amino‐3‐(4‐methylthiophenyl)‐benzotrifluoride. Treatment of this compound with osmium tetroxide in the presence of 4‐methyl morpholine‐N‐oxide yielded the corresponding sulfone, which was converted into the iodo derivative using sodium nitrite. The iodo derivative thus obtained was treated first with propylmagnesium chloride and triethylborane and subsequently with hydroxylamine‐O‐sulfonic acid to furnish the target compounds. 相似文献
50.
Conformational energy calculations are presented for the head-to-head dimerized β helices for Gramicidin A transmembrane channel structures. The calculations take into account both left- and right-handed β helices, and various side-chain conformations. The energetics of the dimerization is studied by considering various docking geometries. It is concluded from these vacuum-energy calculations that the lowest energy conformation for the channel dimer is that comprised of left-handed β helices. 相似文献