Field-force alignment of disc-type pi systems.

The ability of electric fields to align nonpolar semiconducting molecules was demonstrated using hexa(para-n-dodecylphenyl)hexabenzocoronene (HBC-PhC12) as a model compound. A solution of HBC-PhC12 was applied to a glass surface by drop-casting and the molecules were oriented into highly ordered structures by an electric field during solvent evaporation. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) showed a long-range alignment where the disclike molecules were organized in columns perpendicular to the direction of the imposed electric field. The high anisotropy of the uniaxially aligned films was characterized by cross-polarized light microscopy. The birefringence of the HBC-PhC12 films was related to the presence of extended domains of unidirectionally aligned columns in which the aromatic cores of the HBC-PhC12 molecules were perpendicular to the columnar axis. The packing and the arrangement of the molecules in the field-force ordered films were proven by electron diffraction and X-ray analyses.     

Structural studies on polymer whiskers by transmission electron microscopy. II. Unit cell of poly(p‐hydroxybenzoic acid) whisker crystal at room temperature

A set of conspicuous reflections, which are not indexed using the cell constants reported so far for poly(p‐hydroxybenzoic acid), were found in the electron diffraction (ED) patterns of its whisker crystal. A new unit cell [a = 1.487 nm, b = 0.572 nm, and c (chain axis) = 1.258 nm, α = β = γ = 90°] was proposed to explain the reflections in question, based on a set of the ED patterns viewed along the different zone axes, which were obtained by tilting the whisker around its long axis. The density of the whisker was experimentally measured to be 1.500 g/cm³, showing that four molecular stems are running through the new unit cell. From the extinction rule, the highest space group was assumed to be Pbca. In this case, the projection of the new unit cell onto the ab‐plane gives a two‐dimensional unit cell with pgm and is basically in agreement with those proposed so far. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2456–2462, 1999     

Physalinol A,a 1,10-seco-physalin with an epidioxy from Physalis alkekengi L. var. franchetii (Mast.) Makino

Physalinol A (1), a novel 1, 10-seco-physalin with a peroxy bridge, was isolated from the organic extracts of Physalis alkekengi L. var. franchetii (Mast.) Makino. The structure was determined on the basis of 1D and 2D NMR spectra and HR-ESI-MS data. The absolute configuration of 1 was evidenced by X-ray diffraction data and further confirmed by ECD calculations. The isolated compound 1 has no cytotoxicity against HCT-116 and PC-3 cancer cell lines and a weak antimicrobial activity against Escherichia coil. In addition, compound 1 also exhibited a weak anti-inflammatory action in lipopolysacaride (LPS)-induced RAW 264.7 macrophages with an IC₅₀ value of 57.3?±?1.03?μM.     

Heterocycles with a bridged nitrogen atom. 12. Recyclization of 5-methyloxazolo[3,2-a]pyridinium cation in the presence of acetylacetone. Crystal structure of 1-acetyl-2,5-dimethylindolizine

Reaction of 5-methyl-2-(p-nitrophenyl)oxazolo[3,2-a]pyridinium perchlorate with acetylacetone gives 1-acetyl-2,5-dimethylindolizine, the structure of which was proved by X-ray analysis.For communication 11 see [1].Dedicated to the anniversary of Professor M. A. Yurovskaya.M. V. Lomonosov State University, Moscow 119899, Russia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 401–405, March, 2000.     

Chemistry of acyl(imidoyl)ketenes. 6. Synthesis and the molecular structure of ethyl 2-oxo-2,5-dihydrofuro[2,3-b]quinoxaline-3-carboxylate

Thermal decarbonylation of ethyl 1,2,4-trioxo-1,2,4,5-tetrahydropyrrolo[1,2-a]quinoxaline-3-carboxylate afforded ethyl 2-oxo-2,5-dihydrofuro[2,3-b]quinoxaline-3-carboxylate. The structure of the resulting compound was established by X-ray diffraction analysis.     

ChemInform Abstract: Electron Diffraction Study of the Molecular Structure of Zirconium Perchlorate in the Gas Phase.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Binuclear and polynuclear transition metal complexes with macrocyclic ligands. 5. Novel complexes of asymmetric polydentate macrocyclic Schiff bases. Step-by-step synthesis

Reactions of 2,6-bis(3-aminopropylaminocarbonyl)pyridine (1) with 4-tert-butyl-2,6-diformylphenol and 2,5-diformylpyrrole in the presence of Ba(ClO₄)₂ in EtOH afford barium complexes with asymmetric macrocyclic Schiff bases as soft and hard ligands. The reaction of compound 1 with Cu(OCOCMe₃)₂ involves closure of a tetrahydropyrimidine ring to give a mononuclear complex, which was structurally characterized by X-ray diffraction analysis.     

Study of alkaloids of Siberian and Altai flora. 8. Crystal and molecular structure of elatidal methylimine hydrate

The crystal and molecular structure of elatidal methylimine hydrate was established by X-ray diffraction analysis and a previous assumption of the E configuration of the methylimino group was confirmed.