Synthesis and chiroptical properties of optically active polymer liquid crystals containing azobenzene chromophores

A series of optically active methacrylic homopolymers, poly[(4‐{4′‐[(S)‐2‐methyl‐1‐butyloxycarbonyl]phenylazo}phenoxyl)x‐methylene methacrylate] (x = 0, 2, 6, or 11), were synthesized. The structures of the polymers were characterized by IR, ¹H NMR, UV, differential scanning calorimetry, and gel permeation chromatography. The chiroptical properties of the polymers in films were investigated with circular dichroism (CD) measurements. The CD and UV spectra of the films suggested that CD absorptions occurred in the films of the polymers with long spacers (x = 6 or 11) but not in the films of the polymers with short spacers (x = 0 or 2). After irradiation with linearly polarized light at 442 nm, the CD values were amplified in all the polymeric films. The amplificatory values of the CD bands in the absorption region (260–360 nm) of azobenzene chromophores suggested that the spacer length had an effect on both the transfer of chirality and photoinduced chirality in the polymeric films. The largest level of photoinduced chirality was induced in the polymer containing six methylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3210–3219, 2006     

Single-electron transistors fabricated with sidewall spacer patterning

We have implemented a sidewall spacer patterning method for novel dual-gate single-electron transistor (DGSET) and metal–oxide–semiconductor-based SET (MOSET) based on the uniform SOI wire, using conventional lithography and processing technology. A 30 nm wide silicon quantum wire is defined by a sidewall spacer patterning method, and depletion gates for two tunnel junctions of the DGSET are formed by the doped polycrystalline silicon sidewall. The fabricated DGSET and MOSET show clear single-electron tunneling phenomena at liquid nitrogen temperature and insensitivity of the Coulomb oscillation period to gate bias conditions. On the basis of the phase control capability of the sidewall depletion gates, we have proposed a complementary self-biasing method, which enables the SET/CMOS hybrid multi-valued logic (MVL) to operate perfectly well at high temperature, where the peak-to-valley current ratio of Coulomb oscillation severely decreases. The suggested scheme is evaluated by SPICE simulation with an analytical DGSET model, and it is confirmed that even DGSETs with a large Si island can be utilized efficiently in the multi-valued logic.     

High-throughput capillary electrophoresis for the identification and differentiation of seven species of Eimeria from chickens

A capillary electrophoretic approach has been evaluated for the identification of seven currently recognised species of Eimeria infecting chickens. The second internal transcribed spacer of ribosomal DNA is PCR-amplified from any of the seven species using a single set of oligonucleotide primers (one of which is fluorescently labelled). The amplicons are heat-denatured and subjected to capillary electrophoresis in a MegaBACE 1000 (Amersham). The chromatograms captured are stored electronically and then analysed using MegaBACE Fragment Profiler software. Using control DNA samples representing monospecific lines of Eimeria, specific peaks in the chromatograms were defined for the unequivocal identification of each of the seven species and their differentiation. Electrophoretic reading and analysis are carried out automatically, thus making it a time- and cost-effective method. This procedure should find applicability as a tool for the quality control of Eimeria vaccines, the monitoring of coccidiosis outbreaks and the high-throughput analysis of oocyst samples for epidemiological surveys.     

Novel phthalocyaninatobis(alkylcarboxylato)silicon(IV) compounds: NMR data and X-ray structures to study the spacing provided by long hydrocarbon tails that enhance their solubility

The reaction between trans-PcSiCl2 (1) and the potassium salts of six fatty acids (2 a-2 f) led to the trans-PcSi[OOC(CH2)nCH3]2 compounds (3 a-3 f), which were characterised by elemental analysis, IR, UV/Vis and 1H, 13C, and 29Si NMR spectroscopy. From a detailed study of the NMR spectra, the strong anisotropic currents of the Pc macrocycle were found to have an effect on up to the sixth methylenic group. As expected, the length of the hydrocarbon tail does not affect the chemical shift of the 29Si nucleus of any of the compounds, appearing at around -222.6. The structures of PcSi[OOC(CH2)nCH3]2, where n = 7, 10, 12, 13 and 20, were determined by X-ray crystallography. All the compounds were found to be triclinic with a P1 space group. In all cases the observed crystallographic pseudosymmetry is Ci and the asymmetric unit consists of half a molecule. The silicon atom is at the centre of a distorted octahedron and hence its coordination number is six. The carboxylate fragments are in a trans configuration with respect to the Pc macrocycle. The supramolecular structures are discussed in detail herein. The correlation between the 1H NMR chemical shifts and the position of the corresponding carbon atoms in the hydrocarbon tail reveals that the dicarboxylate substituents exhibit a spacer-like behaviour that enhances the solubility. A detailed study of the tail variable allowed us to evaluate the loss of radial shielding along the Pc2- ligand.     

Synthesis and electrochemical characterization of dipyrroles separated by diphenyleneoxide and diphenylenesulfide spacers via the Trofimov reaction

4,4′-Bis[2-(1-vinylpyrrolyl)]diphenyloxide, 4,4′-bis(2-pyrrolyl)diphenylsulfide, 4-(2-pyrrolyl)-4′-[2-(1-vinylpyrrolyl)]diphenylsulfide and 4,4′-bis[2-(1-vinylpyrrolyl)]diphenylsulfide have been synthesized in a one-pot procedure from oximes of corresponding diacetylphenylenoxide and -sulfide through their reaction with acetylene in the MOH-DMSO systems (M=Li, K) at 80-130 °C under pressure of 10-15 atm, thus illustrating applicability and general character of the reaction of synthesis of diverse dipyrrole-phenylene assemblies and their N-vinyl derivatives. Two of the pipyrroles are promising for creating new conducting polymers with sulfur and oxygen atoms in the conjugation chain and for the study of the influence of the diphenyleneheteroatom moiety on conductivity of final polymer products. For the dipyrroles with the diphenyleneheteroatom moieties and 1,4-phenylene spacer the luminescence characteristics were determined.     

新型非离子表面活性剂的合成与表征

环氧化合物;新型非离子表面活性剂的合成与表征;疏水间隔链;聚氧乙烯     

Syntheses and properties of ethoxylated double‐tail trisiloxane surfactants containing a propanetrioxy spacer

A new type of ethoxylated double‐tail trisiloxane surfactants containing a propanetrioxy spacer of the general formula ROCH₂CH(OR)CH₂O(CH₂CH₂O)_xCH₃ [R = Me₃SiOSiMe(CH₂)₃OSiMe₃, x = 8.4, 12.9, 22] has been synthesized. Their structures were characterized by ¹H‐NMR, ¹³C‐NMR and ²⁹Si‐NMR spectroscopy. The critical micelle concentration (CMC) values of these double‐tail trisiloxane surfactants were at the level of 10⁻⁵ mol l⁻¹, and the surface tension values of their aqueous solutions at CMC were in the range of 21‐24.9 mN m⁻¹. Only the double‐tail trisiloxane surfactant with average ethoxy units of 8.4 ( 1P ) possesseda good spreading ability (SA) value. Its SA values of aqueous solutions (5.0 × 10⁻³ mol l⁻¹) on parafilm and Ficus microcarpa leaf surfaces were more than 15 (within 10 min) and 13 (within 3 min), respectively. The trisiloxane surfactant 1P was also found to have the strongest hydrolysis resistant ability among all of the double‐tail trisiloxane surfactants prepared. Its aqueous solutions were stable for 130 days in an acidic environment (pH 4.0) and 59 days in an alkaline environment (pH 10.0) with surface tension values less than 23 mN m⁻¹. It is suggested that this surfactant can be used as a wetting agent or spreading agent in certain extreme pH environments. Copyright © 2011 John Wiley & Sons, Ltd.     

适宜海水钻井液体系新前置液实验和现场试验

前置液是影响固井质量的重要因素之一，对于海水钻井液体系，如何选用前置液是一个新的 课题. 提出了一种适宜于海水钻井液体系的新型前置液，对其在固井过程中的各种性能 进行了室内实验研究，结果表明：新型前置液与海水钻井液、固井水泥浆及盐水等环境流体 有良好的相容性，对井壁具有稳定作用，其中的固体颗粒及表面活性剂有利于冲刷海水钻井 液形成的泥饼. 在此基础上，将新型前置液应用于胜利油田的固井作业，进行现场试验，发 现：应用新型前置液后，环空水泥浆界面清晰，混浆段长度缩短，第2界面的胶结质量有明 显提高.     

Synthesis and Surface Properties of Novel N-Alkyl Quinoline-Based Cationic Gemini Surfactants

Two series of cationic dimeric (gemini) surfactants are prepared with respect to key surfactants properties, such as surface activity and solubilization. The influence of both the dimerization and the spacer group is examined in order to establish structure-property relationships. The surface tension and critical micelle concentration can be markedly reduced compared to the monomeric surfactants in the pure state. The critical micelle concentration (cmc) of each series has been determined using equilibrium surface tension measurements. Furthermore, air/water interface parameters including effectiveness (π_cmc), efficiency (P_C20), maximum surface excess (Γ _max ), and minimum surface area (A _min ) have been also derived using Gibb's adsorption equation at 25°C. Standard free energies of micellization and adsorption were calculated. Solubilization behaviors of the synthesized surfactants were measured towards paraffin oil as solubilized material using light transmission technique.     

Why do non-symmetric dimers intercalate? The synthesis and characterisation of the α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-(2-methylbutyl-4′-(4″-phenyl)benzoateoxy)alkanes

Ten new non-symmetric liquid crystal dimers belonging to the family of compounds α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-(2-methylbutyl-4′-(4″-phenyl)benzoateoxy)-alkanes have been synthesised and their transitional properties characterised. The dimers contain either a hexamethylene or octamethylene spacer, while the terminal substituents on the 4-benzylideneaniline fragment are H, CH₃, F, Cl and Br. The unsubstituted dimers are not liquid crystalline, while the remaining compounds exhibit enantiotropic nematic behaviour. The trends in the clearing temperatures, according to the chemical nature of the terminal substituent, are largely consistent with those established for conventional low molar mass liquid crystals. Three of the dimers also exhibit an intercalated smectic A phase, specifically the two bromo-substituted dimers and the chloro-substituted dimer containing a hexamethylene spacer. The driving force for the formation of this phase is considered to be, at least in part, the specific anisotropic interaction between the unlike mesogenic units. The absence of smectic behaviour for the isosteric methyl-substituted dimers reveals that steric factors alone cannot stabilise the intercalated smectic A phase.