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1.
Kamlakar Avasthi Diwan S. Rawat Tilak Chandra Ashoke Sharon Prakas R. Maulik 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o311-o313
In 5-benzyl-1,7-dimethyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-d]pyrimidine-4,6-dione, C14H14N4O2, which crystallizes in space group P, weak intermolecular C—H⋯O hydrogen bonds generate dimers. The isomeric compound 1-benzyl-5,7-dimethyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-d]pyrimidine-4,6-dione, C14H14N4O2, crystallizes in space group P21/n, and shows no such dimerization. Instead, it exhibits C—H⋯π interactions with the phenyl ring. In both structures, the molecules are linked by aromatic π–π-stacking interactions. 相似文献
2.
Shashank Tripathi Achu Chandran Tilak Joshi Anil Kumar Ajay Dhar 《Liquid crystals》2013,40(9):1255-1262
In this article, a newly synthesised ferroelectric liquid crystal (FLC) material, namely LAHS 22, has been characterised. The characterisation of the FLC material has been performed using dielectric relaxation spectroscopy, differential scanning calorimetry and polarisation optical microscopy. We observed an enhancement in the dielectric and electro-optical properties of the FLC material by incorporating gold nanoparticles (GNPs)-decorated multiwalled carbon nanotubes (MWCNTs). The GNPs-decorated MWCNTs cause an increment in dielectric dispersion (up to kHz), absorption, spontaneous polarisation and rotational viscosity of the FLC material. The pure and GNPs-decorated MWCNTs doped FLC cells were analysed by means of various dielectric spectroscopic and optical measurements. The observed enhancement in the dielectric and electro-optical properties of the FLC material has also been studied with concentration of GNPs-decorated MWCNTs in FLC material. The GNPs-decorated MWCNTs/FLC composites are not only of fundamental importance, but also useful materials for device applications such as liquid crystal displays and memory devices. 相似文献
3.
Summary We consider a (possibly) vector-valued function u: RN, Rn, minimizing the integral
, 2-2/(n*1)<p<2, whereD
i
u=u/x
i
or some more general functional retaining the same behaviour, we prove higher integrability for Du: D1 u,..., Dn–1 u Lp/(p-1) and Dnu L2; this result allows us to get existence of second weak derivatives: D(D1 u),...,D(Dn–1u)L2 and D(Dn u) L
p.This work has been supported by MURST and GNAFA-CNR. 相似文献
4.
Sanjay K. Bharti Saurabh K. Patel Gopal Nath Ragini Tilak Sushil K. Singh 《Transition Metal Chemistry》2010,35(8):917-925
Six Cu(II) complexes of Schiff base ligands of arylidene-2-(4-(4-bromo/methoxy-phenyl)thiazol-2-yl) hydrazines have been synthesized,
characterized and screened for DNA cleavage and antimicrobial activities. The chemical structures of the complexes were deduced
by physicochemical and spectroscopic methods. Elemental analyses indicated that the stoichiometry of the complexes is CuL2 (L = Schiff base ligand). The DNA cleavage activities of the complexes were evaluated by agarose gel electrophoresis in the
presence and absence of oxidant (H2O2) and free radical scavenger (DMSO). All the six complexes showed significant nuclease activity in the presence of H2O2, and two of the complexes showed moderate nuclease activity even in the absence of oxidant. The complexes did not show nuclease
activity in the presence of free radical scavenger. The compounds were tested for activity against selected bacteria and fungi. 相似文献
5.
6.
A. I. El-Shora Rex A. Palmer Harkishan Singh Tilak Raj Bhardwaj Dharam Paul 《Journal of chemical crystallography》1984,14(1):89-115
The crystal structures of two forms of 17-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene (HS-625) are reported. In HS-625 (aqueous solvate) form 1, moleculeA, and HS-625 (anhydride) form 2, moleculeB, the pyrrolidine group is 3- substituted, while in HS-625 (anhydride) form 2, moleculeC has its pyrrolidine ring -substituted. HS-625 form 1 is orthorhombic, space groupP212121, witha=7.089(4),b=11.502(6),c=28.975(16) Å,Z=4; form 2 is triclinic, space groupP1, witha=14.013(8),b=12.572(6),c=6.688(4) Å, =95.187(20), =103.491(21); =86.210(20)°,Z=2. MoleculesA andB have similar geometry, differences in moleculeC being related to strain caused by the unusual 3- ring substituent which also produces a pronounced kink in the backbone of the molecule. An unusual feature of the analysis of form 1 is the location of the water hydrogens in the difference electron density well above background. None of the OH hydrogens was located. Both structures are hydrogen bonded, but the pyrrolidine nitrogen N(31) in moleculeC is heavily congested and is unable to act as an acceptor. The hydroxyethyl side chain, important for activity, has a different conformation in the three molecules (t,g, t,-g, andt,t respectively). 相似文献
7.
8.
A selective synthesis of α-anomers of indoline nucleosides is described. Ribonucleosides of indoline, dimethylindoline and 5-bromoindoline are readily prepared in good yield by reacting indoline bases directly with the protected sugar, 2,3-O-(1-methylethylidene) 5-O-(triphenylmethyl)-D-ribofuranose in dry ethanol or methylene chloride in presence of molecular sieves at 40-60 °C. 相似文献
9.
Unsuccessful attempts have been made to synthesize the pyrrolo analogues of equilenin and 3-desoxyequilenin. The synthesis of several carbazole derivatives required in this connexion is described. 相似文献
10.