1,3‐Bis[2‐(2‐hydroxybenzylideneamino)phenoxy]propane

The title compound {systematic name: 2,2′‐[1,3‐propanediyldioxydi‐o‐phenylenebis(nitrilomethylidyne)]diphenol}, C₂₉H₂₆N₂O₄, exists as the phenol–imine form in the crystal, and there are strong intramolecular O—H⋯N hydrogen bonds, with O⋯N distances of 2.545 (2) and 2.579 (2) Å. The C=N imine bond distances are in the range 1.276 (2)–1.279 (2) Å and the C=N—C bond angles are in the range 123.05 (16)–124.64 (17)°. The configurations about the C=N bonds are anti (1E).     

Morphology and thermal characterization of montmorillonite/polybenzimidazole nanocomposite

In this study, thermal and morphological properties of organically modified montmorillonite (mMMT)/poly(2,5-benzimidazole) (ABPBI) composite were investigated. The morphology and structure of mMMT/ABPBI composites were characterized by infrared, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis techniques. At low mMMT loading levels, exfoliation was the predominant mechanism of mMMT dispersion. At high mMMT loading levels, nonintercalated microcomposite morphology is partially favored in expense of the intercalated nanocomposite. Thermal degradation of nanocomposite occured in three stages. In the second stage of thermal degradation, the onset temperature of degradation for the mMMT/ABPBI nanocomposites was lower than that of ABPBI polymer. In the last stage, the improvement in thermal stability by the introduction of mMMT into the ABPBI was different from the second stage. The activation energy for degradation of ABPBI increased from 62.6 to 77.7 kJ mol^?1 after loading of 5 mass% of mMMT into ABPBI matrix under air atmosphere.     

The structure of a new crystalline cevane alkaloid: its identity with persicanidine B and harepermine

The structure of a new crystalline base (melting point (mp) 167-169 degrees C) obtained from Fritillaria imperialis was elucidated as (20R, 25R)-5alpha,17beta-cevanine-3beta,6beta-diol, X-ray diffraction analysis of the mono-hydrate. The base was found to be identical with persicanidine B and also with harepermine.     

Solution processable organic field-effect transistors utilizing an alpha,alpha'-dihexylpentathiophene-based swivel cruciform

A pentathiophene-based swivel cruciform, which allows rotation between the cruciform arms, was synthesized. Homogeneous microcrystalline films were processed from solution, and field-effect transistors utilizing this dimer gave hole mobilities up to 0.012 cm2/V.s.     

The indenobenzazepine-spirobenzylisoquinoline rearrangement; stereocontrolled syntheses of (±)-raddeanine and (±)-yenhusomine

Stereoselective rearrangement of indenobenzazepine cis ketols $\text{2}$ and $\text{5}$ with TPAA in pyridine produces spirobenzylisoquinolines $\text{3}$ and $\text{6}$, respectively. The latter product is also obtained by rearrangement of trans ketol $\text{7}$. The transformation of ketols $\text{5}$ and $\text{7}$ must, therefore, proceed through the intermediacy of aziridinium cation $\text{9}$. A similar process obtains in the transformation of $\text{2}$ to $\text{3}$. NaBH₄ reduction of $\text{3}$ gives (±)-raddeanine ($\text{4}$). Rearrangement of diol $\text{10}$ supplies $\text{4}$ directly. (±)-Yenhusomine ($\text{13}$) is obtained from the reamangement of either diol, $\text{11}$ or $\text{12}$. In like fashion, diols $\text{14}$ and $\text{15}$ supply spirobenzylisoquinoline $\text{17}$.     

Solution and ellipticity properties of the self-duality equations of Corriganet al. in eight dimensions

We study the two sets of self-dual Yang-Mills equations in eight dimensions proposed in 1983 by E. Corriganet at. and show that one of these sets forms an elliptic system under the Coulomb gauge condition, and the other (overdetermined) set can have solutions that depend at most onN arbitrary constants, whereN is the dimension of the gauge group, hence the global solutions of both systems are finite dimensional. We describe a subvarietyP ₈ of the skew-symmetric 8 x 8 matrices by an eigenvalue criterion and we show that the solutions of the elliptic equations of Corriganet al. are among the maximal linear submanifolds ofP ₈. We propose an eighth-order action for which the elliptic set is a maximum.     

A modular "toolbox" approach to flexible branched multimacrocyclic hosts as precursors for multiply interlocked architectures

Tetralactam macrocycles can be functionalized by a variety of cross-coupling reactions. A modular "toolbox" strategy is presented that allows 1) several tetralactam macrocycles to be covalently connected with each other or with a central spacer, 2) the macrocycles to be substituted with or connected to different chromophores, and 3) metal-coordination sites to be attached to the macrocycles. With this approach a series of different oligo-macrocyclic hosts was obtained with great structural diversity and enormous potential for further functionalization. Rotaxanes made on the basis of these macrocycles have been synthesized to demonstrate their utility in building more complex supramolecular architectures.