Fast switching ferroelectric side-chain liquid-crystalline polymer and copolymer

New ferroelectric side-chain liquid-crystalline polymers, a copolymer and a homopolymer, with siloxane backbone and a triaromatic mesogen as the side group have been synthesized. The materials exhibit a chiral smectic C phase over a large temperature range extending to room temperature. They possess high values of spontaneous polarization: 105 nC cm^-2 for the homopolymer and 180 nC cm^-2 for the copolymer. The electro-optic switching time in the chiral smectic C phase is extremely fast (150 μs). In the smectic A phase, an electroclinic effect with switching times less than 100 μs and with field induced tilt angles of 18° is observed.     

Structural changes by sulfoxidation of phenothiazine drugs

Summary The side-chain conformations of psychoactive phenothiazine drugs in crystals are different from those of biologically inactive ring sulfoxide metabolites. This study examines the potential energies, molecular conformations and electrostatic potentials in chlorpromazine, levomepromazine (methotrimeprazine), their sulfoxide metabolites and methoxypromazine. The purpose of the study was to examine the significance of the different crystal conformations of active and inactive phenothiazine derivatives, and to determine why phenothiazine drugs lose most of their biological activity by sulfoxidation. Quantum mechanics and molecular mechanics calculations demonstrated that conformations with the side chain folded over the ring structure had lowest potential energy in vacuo, both in the drugs and in the sulfoxide metabolites. In the sulfoxides, side chain conformations corresponding to the crystal structure of chlorpromazine sulfoxide were characterized by stronger negative electrostatic potentials around the ring system than in the parent drugs. This may weaken the electrostatic interaction of sulfoxide metabolites with negatively charged domains in dopamine receptors, and cause the sulfoxides to be virtually inactive in dopamine receptor binding and related pharmacological tests.     

Capturing a metastable chiral polymorph of an achiral molecule--hexa-O-benzoyl-myo-inositol

myo-Inositol hexabenzoate having meso configuration produces chiral polymorph (form I) when crystallized rapidly but yields achiral polymorph (form II) when allowed to crystallize slowly; in the mother liquor form I slowly but completely disappears to give form II.     

A versatile and efficient synthesis of (2S)-2-(hydroxymethyl)-N-Boc-2,3-dihydro-4-pyridone

A versatile and efficient method for the preparation of (2S)-2-(hydroxymethyl)-N-Boc-2,3-dihydro-4-pyridone from l-(−)-phenylalanine 2 utilising the aromatic system as a masked β-keto aldehyde was developed. The key step in the sequence is an intramolecular cyclisation of 6 to give 2,3-dihydropyridin-4-ones.     

Ru2(ap)4(sigma-oligo(phenyleneethynyl)) molecular wires: synthesis and electronic characterization

Reported in this contribution are the synthesis, characterization, and charge transport properties of wire-like Ru2(ap)4(OPEn), where ap is 2-anilinopyridinate and OPE is -(CCC6H4)nSCH2CH2SiMe3 with n = 1 (1) and 2 (2). Scanning tunneling microscopy (STM) measurements of compound 2 inserted into a SAM of C11 thiol reveal that molecule 2 exhibits (i) the stochastic switching characteristic of wire molecules embedded in insulating SAMs and (ii) higher conductivity than the C11 thiol SAM. More importantly, analysis of the molecular electronic decay constant (beta) exhibits a decrease of at least 15% as compared to purely organic molecular analogues. Hence, the transport characteristics of molecules can be significantly improved for nanoscale electronics through the incorporation of a Ru2 fragment into conjugated backbone.     

Effectiveness of radiation processing in elimination of Campylobacter from poultry meat

Campylobacter, a common poultry intestine commensal, is a well known cause of human gastric illnesses across the globe. Consumption of contaminated poultry meat is a major cause of Campylobacter related infections. In the present study, radiation sensitivity of indigenous strains of C. jejuni and C. coli isolated from poultry was evaluated. The decimal reduction dose (D₁₀) values of different Campylobacter isolates at 0-4 °C in saline and blood broth were in the range of 0.120-0.210 kGy and 0.170-0.234 kGy, respectively. D₁₀ values in chicken meat homogenate for Campylobacter were in the range of 0.110-0.190 kGy. Chicken meat samples were inoculated with C. jejuni and exposed to gamma radiation to study the effectiveness of radiation treatment in elimination of Campylobacter. Radiation treatment with a dose of 1 kGy could achieve complete elimination of 10⁵ CFU of Campylobacter/g in poultry meat samples. No recovery of Campylobacter was observed, even after enrichment and selective plating in 1 kGy treated chicken meat samples stored at 4 °C up to 7 days. Present study shows that irradiation of poultry meat with 1 kGy can ensure safety of poultry meat.     

Evidence of continuous evolution of smectic A2 from smectic Ad

Abstract

We present here precise measurements of the layer spacing for two compounds, viz. 4-n-heptyloxyphenyl-4′-(4″-cyanobenzoyloxy)benzoate and 4-n-undecyloxyphenyl-4′-(4″-cyanobenzyloxy)benzoate. Contrary to earlier reports our data do not show any jump in the layer spacing at the expected A_d-A₂ transition temperature, showing thereby that for both compounds A₂ evolves continuously from the A_d phase.     

Synthetic studies of stereocalpin A and its C5-epimer: total synthesis of 11-epi- and 5,11-diepi-stereocalpin A

This Letter describes the synthetic studies of stereocalpin A and its C5-epimer. After various cyclization attempts, successful macrolactamization at 9-10 position was tried inorder to obtain stereocalpin A and its C5-epimer, which were accompanied by complete racemization and resulted in the synthesis of 11-epi- and 5,11-diepi-stereocalpin A. Highly functionalized octanoic acid motif of the depsipeptide was constructed by applying Paterson’s aldol methodology, owing to its diversity in synthesizing various analogs of aliphatic acid.     

Synthesis and applications of phosphatidylinositols and their analogues

There is an upsurge of interest in the chemistry and biochemistry of phosphoinotides, their analogues and the related enzymes due to their involvement in the inositol phosphates mediated cellular signal transduction pathways. The present review deals with the recent developments in the synthesis and applications of phosphatidylinositol and its derivatives. NCL commun, no. 6014