Gramicidin, a linear polypeptide composed of hydrophobic amino acids with alternating L- and D- configurations, forms transmembrane ion channels. The crystal structure gramicidin-cesium complex has been determined at 2.0 angstrom resolution. In this structure, gramicidin 26 long tube comprised two chains arranged as antiparallel beta strands that are wrapped into left-handed helical coil 6.4 residues per turn. backbone the interior hydrophilic, solvent-filled pore side form relatively...

The dichloro[(-)-sparteine-N,N']copper(II) complex provides Henry adducts with high enantioselectivities (73-97% ee) in reaction between nitromethane and various aldehydes.

Three new lamellarin alkaloids, lamellarins gamma (1), alpha (2), and epsilon (3), along with eight known M (4), K (5), K-diacetate (6), K-triacetate (7), U (8), I (9), C-diacetate (10), X-triacetate (11), have been isolated from the Indian ascidian Didemnum obscurum. The structures of 1-11 were established using standard spectroscopic techniques. structure (7) was further confirmed by X-ray crystallographic analysis. antioxidant properties gamma, gamma-monoacetate, K, U, I, evaluated.

Structurally well defined and thermally stable Pd(II) complexes, derived from N4-tetradentate dicarboxyamide/dipyridyl ligands, were evaluated as catalysts for the Heck reactions of deactivated aryl chlorides olefins (see scheme). The concept using an anionic carboxyamide ancillary ligand palladium demonstrated here provides a new opportunity development phosphine-free transition-metal catalysis.

A two-step protocol for the diversity-oriented synthesis of annulated indoles following MCR-post MCR modification concept is described. The reaction initially proceeds through annulation 2-(2,2-dibromovinyl)aniline, an isocyanate, and a terminal alkyne in three-component tandem format via Cu/Pd-catalyzed cross coupling to afford N-1 C-2 functionalized indole. In subsequent step, enyne–urea derivative undergoes chemo- regioselective 6-endo cyclization O-cyclized product presence Au(I)/AgNO3...

In the present study we report existence of sixth polymorph aripiprazole (APPZ) as characterised by single-crystal X-ray diffraction, and its structural lattice energy comparison with five other polymorphs APPZ in Cambridge Structural Database (CSD). Incidentally, six well happens to be second most polymorphic system CSD after classic ROY molecule which has a record number seven polymorphs. The extensive polymorphism title compound is attributed very high degree conformational freedom,...

The butylidene-linker models 1-[2-(2,6-dimethylsulfanyl-9 H -purin-9-yl)-2-methylidenepropyl]-4,6-bis(methylsulfanyl)-1 -pyrazolo[3,4- d ]pyrimidine, C 18 20 N 8 S 4 , (XI), 7,7′-(2-methylidenepropane-1,3-diyl)bis[3-methyl-2-methylsulfanyl-3 -pyrrolo[2,3- ]pyrimidin-4(7 )-one], 22 6 O 2 (XIV), and 7-[2-(4,6-dimethylsulfanyl-1 ]pyrimidin-1-yl)-2-methylidenepropyl]-3-methyl-2-methylsulfanyl-3 )-one, 19 21 7 OS 3 (XV), show folded conformations in solution, as shown by 1 NMR analysis. This...

An effective inhibitor of cyclo-oxygenase. Mr=230.25 , monoclinic, P21, a= 13.3150(10), b = 5.7765 (4), c= 7.8732 (4)A, fl= 93.88 (1) °, V= 604.2 (1)A 3, Z= 2, Din= 1.25 (2) (flotation), D~= 1.265 Mg m -3, 2(Mo Ka 1) 0.70926/~, #(Mo Ka) 0.095 mm -1, F(000) 244, T= 296 K, final R(F) 0.061 for 1037 observed reflections. The rotation the carboxyl group with respect to benezene ring, which seems be connected anti-inflammatory potential, is similar other two substituted propionic acids already...

Structural reasons for the melting point variations in isostructural cocrystals of aripiprazole drug are investigated through combined spectroscopic and diffraction studies.

Olanzapine is an antipsychotic drug which shows donor–acceptor disparity in its polymorphic crystal structures. A strong hydrogen bonding acceptor, piperazine nitrogen, left unutilized. We reasoned that including hydroquinone as a coformer with two hydroxyl donor groups could overcome the and facilitate stronger phenol⋯piperazine phenol⋯diazepine supramolecular synthons between coformer. Our co-crystallization attempts were successful toluene solvent. Two distinct morphologies observed...

In this manuscript, we discuss two novel polymorphic crystal structures of metformin–embonate, a drug widely known for its use in anti-diabetic treatments. Form I crystallizes the monoclinic P21/c space group and form II triclinic P group. Both polymorphs contain 2 : 1 stoichiometry metformin embonic acid. Proton transfer results guanidinium carboxylate ion pair which has well aligned donor acceptor groups effective hydrogen bonding. Two types guanidinium–carboxylate variations are observed...

Four derivatives of 2,4,6-tris(benzylamino)-1,3,5-triazine are synthesized and detailed computational nonlinear optical investigations carried out. Computations indicate near degenerate conformations (C3 C1 symmetry) in all systems the gas phase; dipole moments also similar magnitude them except molecule 4 [2,4,6-tris(4-fluorobenzylamino)-1,3,5-triazine]. HRS measurements these molecules solution reveal moderately large β values; structure–property relations analyzed through computations....

In lamotrigine [systematic name: 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine], C(9)H(7)Cl(2)N(5), (I), the asymmetric unit contains one base molecule. lamotriginium chloride 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium chloride], C(9)H(8)Cl(2)N(5)(+).Cl(-), (II), cation and anion, while in nitrate, C(9)H(8)Cl(2)N(5)(+).NO(3)(-), (III), two crystallographically independent cations nitrate anions. all three structures, N-H...N hydrogen bonds form an R(2)(2)(8) dimer. (I)...

Two novel crystal structures of dutasteride (hemihydrate and hydrochloride salt, crystallised before after protonation respectively) are presented. Interestingly, in the only cyclic amide was protonated, but not phenyl amide. The is attributed to increase resonance that results significant acceptor strength (or basicity) O.

The analysis of Cambridge Structural Database (CSD) on cytosine–acid complexes indicated a strong competition between two-point 2-aminopyridinium–carboxylate synthon and three-point cytosinium–cytosine synthon. Statistics surprisingly showed higher probability for the rather than highly robust (66% vs. 33%). exact reasons contributing to this unusual preference are elucidated in present study with structural analyses four cytosine aromatic carboxylic acids viz., 2,5-dihydroxybenzoic acid...

Four derivatives of 2,4,6-tris(benzyloxy)-1,3,5-triazine are synthesized and detailed computational non-linear optical investigations carried out. Computations indicate four conformations with different energies in all the systems gas phase; individual dipole moments also magnitude. HRS measurements these molecules solution reveal moderately large β values; structure–property relations analyzed through computations. These have one added advantage nearly 100% transmission visible range, due...