Synthesis and properties of optically active 1,3-diols and their derivatives as chiral dopants for ferroelectric liquid crystals

New chiral dopants β-hydroxy ketones 1, 1,3-diols 2, 1,3-dioxanes 3 and 1,3-dioxan-2-ones 4 were designed and synthesized. Reaction of (R)-1,2-epoxyoctane with carbanions derived from 2-(4-substituted phenyl)-1,3-dithianes followed by hydrolysis of the resulting hydroxy dithianes afforded 1. Reduction of 1 gave the diols 2, which yielded 3 upon acetalization and 4 upon carbonation. The syn isomers of 2, 3, and 4 exhibited larger spontaneous polarizations, when applied as chiral dopants, than the anti isomers or hydroxy ketones 1.     

Two regioisomers of condensed thioheterocyclic triazine synthesized from 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one

In the crystal structure of 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one, C₉H₇N₃OS, (I), the 1,2,4‐triazine moieties are connected by face‐to‐face contacts through two kinds of double hydrogen bonds (N—H...O and N—H...S), which form planar ribbons along the a axis. The ribbons are crosslinked through C—H...π interactions between the phenyl rings. The molecular structures of two regioisomeric compounds, namely 6‐phenyl‐2,3‐dihydro‐7H‐1,3‐thiazolo[3,2‐b][1,2,4]triazin‐7‐one, C₁₁H₉N₃OS, (II), and 3‐phenyl‐6,7‐dihydro‐4H‐1,3‐thiazolo[2,3‐c][1,2,4]triazin‐4‐one, C₁₁H₉N₃OS, (III), which were prepared by the condensation reaction of (I) with 1,2‐dibromoethane, have been characterized by X‐ray crystallography and spectroscopic studies. The crystal structures of (II) and (III) both show two crystallographically independent molecules. While the two compounds are isomers, the unit‐cell parameters and crystal packing are quite different and (II) has a chiral crystal structure.     

Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene

We report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.     

Synthesis of febrifugine derivatives and a solution to the puzzle of the structural determination of febrifugine

The stereo-structure of piperidine lactone (3), a synthetic intermediate of the antimalarial agent febrifugine ((+)-1) with a piperidine ring in the trans relative configuration, was re-revised to the cis-form. We determined that isomerization to the trans-form from the cis-form occurred in the stage (6 from 5) of deprotection in Baker's synthesis.     

Targeted proteo-glycomics analysis of Sialyl Lewis X antigen expressing glycoproteins secreted by human hepatoma cell line.

Sialyl Lewis X (SLEX) antigen, Neu5Acalpha2-3Galbeta1-4 (Fucalpha1-3) GlcNAc-R, plays important roles in cell-to-cell interaction: for example, the E- and P-selectin-mediated influx of SLEX expressing leukocytes into inflamed areas. A human hepatocellular carcinoma cell line, HepG2 cells, was highly expressed SLEX on secreted glycoproteins and cell surface, in contrast with HuH-7 cells. We identified SLEX expressing glycoproteins in HepG2 cultured medium by two-dimensional polyacrylamide gel electrophoresis, followed by in gel digestion and peptide mass fingerprint using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS), including transferrin, alpha1-antitrypsin, alpha2-HS glycoprotein and beta-glycoprotein. We analyzed N-glycans of these glycoproteins by MALDI-TOFMS in combination with exoglycosidase digestion; our results indicate increases in poly-fucosylated and high-branched N-glycans. High alpha1,3-fucosylation in glycoproteins would be caused by increased expression of alpha1,3-fucosyltransferase activities in HepG2 cells.     

Synthesis of novel macromonomers and telechelics of poly(2-alkyl-2-oxazoline)s

Novel macromonomers and telechelics of poly(2-alkyl-2-oxazoline) (PROZO) were syn-thesized by utilizing termination of propagating species (2-oxazolinium ions) in the living polymerization of 2-alkyl-2-oxazoline (ROZO) with suitable nucleophiles. Two types of p-vinylbenzyl–type macromonomers were obtained by terminating living PROZO with sodium p-vinylbenzyl alkoxide or with sodium p-vinylbenzyl mercaptide. The synthesis of telechelics having a functional group (SH, COOH) on both ends of PROZO was achieved by using a bis(2-oxazolinium salt) initiator. The PROZO dithiol was synthesized by two methods: (1) termination of the living species on both ends with NaSH, and (2) aminolysis of PROZO bis(O-ethyldithiocarbonate) given by treatment of the living PROZO with potassium O-ethyldithiocarbonate. Termination of the living PROZO with the sodium salt of di-t-butyl malonate yielded a PROZO with di-t-butyl malonate moieties on both polymer ends, from which the PROZO dicarboxylic acid was derived via free tetracarboxylic acid. © 1995 John Wiley & Sons, Inc.     

Effect of an "ionic liquid" cation, 1-butyl-3-methylimidazolium, on the molecular organization of H2O

The excess partial molar enthalpy of 1-propanol (1P), , was measured at 28 degrees C in the ternary mixture of 1P-1-butyl-3-methylimidazolium chloride ([bmim]Cl)-H(2)O in the H(2)O-rich composition range. From these data we evaluated what we call the 1P-1P enthalpic interaction function, . Its changes induced by addition of [bmim]Cl of the pattern of were used as a probe to elucidate the effect of [bmim]Cl on the molecular organization of H(2)O. It was found that the effect of Cl(-) was not conspicuous within this methodology, and the observed dependence is predominantly due to the hydration of [bmim](+). The changes in the x(1P)-dependence of were compared with those brought about by temperature increase, or by the addition of fructose or glycerol. It was found that the effect of [bmim](+) is similar to that of fructose or increased temperature. We speculate that in the H(2)O-rich composition region a number of H(2)O molecules are attracted to the delocalized positive charge of the imidazolium ring and the bulk of H(2)O is influenced in such a manner that the global hydrogen bond probability is reduced.     

Synthesis of allenes from allylic alcohol derivatives bearing a bromine atom using a palladium(0)/diethylzinc system

A general and efficient synthesis of allenes using a palladium(0)/diethylzinc system is described. Treatment of mesylates or trichloroacetates of (E)- or (Z)-2-bromoalk-2-en-1-ols with diethylzinc in the presence of a catalytic amount of palladium(0) affords allenes bearing an aminoalkyl, alkyl, or aryl substituent(s) in good to high yields. No transfer of chirality from the stereogenic center carrying the mesyloxy group to the allene was observed.     

Quantitative confirmation of the crystal-amorphous interphase in semicrystalline poly(vinylidene fluoride) and poly (vinylidene fluoride)/poly (ethyl methacrylate) blends

Dielectric and thermal characterizations were performed for poly (vinylidene fluoride) (PVDF)/poly (ethyl methacrylate) (PEMA) blends of different composition. The characteristics of PVDF β relaxation were shown to be little affected in the semicrystalline blends with PEMA. The relaxation strength, however, depends strongly on the PEMA content and a linear relation was found between the intensity of the β relaxation and the weight fraction of the PVDF crystal-amorphous interphase. Phase structures of the PVDF/PEMA blends are also proposed. © 1994 John Wiley & Sons, Inc.