Conformation of 4-ethoxy-4′-biphenylyl cyanide in the isotropic and anisotropic liquid-crystalline state — a rotational isomeric state simulation of 2H NMR spectra

The conformation of the ethoxy tail flanking the cyanobiphenyl core has been studied in the liquid-crystalline phase as well as in the isotropic solution. In solution, the vicinal coupling constant ³J_CH for the moiety C^phO CH (C^ph: phenyl carbon) provided the information regarding the rotation around the O C bond. Phenetole was mostly used as a model compound. The conventional rotational isomeric state (RIS) analysis yielded the energy difference between the gauche and trans state to be of the order of 1,6 to 1,4 kcal/mol in CDCl₃, C₆D₆ and dimethyl-d₆ sulfoxide. In this treatment, the rotational state around the neighboring bond (C^ph O) was taken to occur at 0 or π. The deuterated compound, 4-ethoxy-4′-biphenylyl-d₇ cyanide, was prepared and studied in the liquid-crystalline state by ²H NMR. The orientational order parameters of the mesogenic core were determined by the analysis of dipolar and quadrupolar splitting data due to aromatic deuterons. The quadrupolar splitting data were also obtained for the deuterated ethoxy tail. The conformation of the tail was elucidated according to the RIS simulation scheme previously proposed. The fraction of the trans conformation f_t was estimated to be 0,79 around the nematic-isotropic transition temperature (T_NI = 91,9°C). It was suggested that the conformation of the ethoxy tail remains nearly unaffected by the phase transition in the immediate vicinity of T_NI. The fraction f_t increases moderately toward an asymptotic value as temperature decreases.     

New Oxyhalide Solid Electrolytes with High Lithium Ionic Conductivity >10 mS cm−1 for All-Solid-State Batteries

All-solid-state batteries (ASSBs) with inorganic solid electrolytes (SEs) have attracted significant interest as next-generation energy storage. Halides such as Li₃YCl₆ are promising candidates for SE because they combine high oxidation stability and deformability. However, the ionic conductivities of halide SEs are not as high as those of other SEs, especially sulfides. Here, we discover new lithium-metal-oxy-halide materials, LiMOCl₄ (M=Nb, Ta). They exhibit extremely high ionic conductivities of 10.4 mS cm⁻¹ for M=Nb and 12.4 mS cm⁻¹ for M=Ta, respectively, even in cold-pressed powder forms at room temperature, which are comparable to or surpass those of organic liquid electrolytes used in lithium-ion batteries. Bulk-type ASSB cells using the oxyhalides as the cathode SE demonstrate an outstanding rate capability with a capacity retention of 80 % at 5 C/0.1 C. We believe that the proposed oxyhalides are promising SE candidates for the practical applications of ASSBs.     

Development of two fully automated quick,easy, cheap,effective, rugged,and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples

Quick, easy, cheap, effective, rugged, and safe extraction strategies are becoming increasingly adopted in various analytical fields to determine drugs in biological specimens. In the present study, we developed two fully automated quick, easy, cheap, effective, rugged, and safe extraction methods based on acetonitrile salting-out assisted liquid-liquid extraction (method 1) and acetonitrile salting-out assisted liquid-liquid extraction followed by dispersive solid-phase extraction (method 2) using a commercially available automated liquid-liquid extraction system. We applied these methods to the extraction of 14 psychotropic drugs (11 benzodiazepines and carbamazepine, quetiapine, and zolpidem) from whole blood samples. Both methods prior to liquid chromatography–tandem mass spectrometry analysis exhibited high linearity of calibration curves (correlation coefficients, > 0.9997), ppt level detection sensitivities, and satisfactory precisions (< 8.6% relative standard deviation), accuracies (within ± 16% relative error), and matrix effects (81–111%). Method 1 provided higher recovery rates (80–91%) than method 2 (72–86%), whereas method 2 provided higher detection sensitivities (limits of detection, 0.003–0.094 ng/mL) than method 1 (0.025–0.47 ng/mL) owing to the effectiveness of its dispersive solid-phase extraction cleanup step. These fully automated extraction methods realize reliable, labor-saving, user-friendly, and hygienic extraction of target analytes from whole blood samples.     

Effect of trifluoromethyl substituents on birefringence of polystyrene

Transparent thermoplastic polymers that exhibit no birefringence are ideal for optical components such as optical films for liquid crystal displays and various lenses. Copolymerization of a positive birefringent monomer with a negative monomer is an effective technique for obtaining low birefringent polymers, especially zero‐photoelastic birefringence polymers that exhibit no photoelastic birefringence even during elastic deformation. We prepared four types of trifluoromethyl‐substituted polystyrenes. By substituting hydrogens at the ortho or meta positions of the benzene ring of polystyrene, we demonstrated that poly(2‐(trifluoromethyl)styrene), poly(3‐(trifluoromethyl)styrene), and poly(3,5‐bis(trifluoromethyl)styrene) had negative photoelastic coefficients. However, poly(4‐(trifluoromethyl)styrene) had a positive photoelastic coefficient similar to that of polystyrene. Based on these results, we synthesized a zero‐photoelastic birefringence polymer of poly(2‐(trifluoromethyl)styrene‐co‐4‐(trifluoromethyl)styrene) (55/45 wt.) exhibiting no photoelastic birefringence in elastic deformation, in which the positive photoelastic birefringence of the poly(4‐(trifluoromethyl)styrene) unit was compensated for by the negative photoelastic birefringence of the poly(2‐(trifluoromethyl)styrene) unit. The discovery of polymers having negative photoelastic coefficients is valuable for the design and synthesis of zero‐photoelastic birefringence polymers. The four types of trifluoromethyl‐substituted polystyrenes are promising optical materials because they have high transparency (transmittance > 89–92% for 27–34‐µm thickness films) in the visible and near‐infrared regions and a high decomposition temperature of approximately 400°C. Copyright © 2016 John Wiley & Sons, Ltd.     

Polymerization of 2,5‐diaminoterephthalic acid‐type monomers for the synthesis of polyamides containing ladder unit

To synthesize ladder‐type polyamides by construction of two amide bonds successively, 2,5‐diaminoterephthalic acid derivatives bearing anthranilic acid ester and isatoic anhydride moieties were synthesized and their polymerization was investigated. Polymerization of the methyl ester monomer proceeded in the presence of lithium hexamethyldisilazide (LiHMDS) as a base in tetrahydrofuran (THF). However, mass spectroscopic analysis of the product suggested that not only the bis(trimethylsilyl)amide anion of LiHMDS but also the methoxide anion eliminated at the second amide‐linkage formation reaction decomposed the isatoic anhydride unit of the growing oligomer by nucleophilic attack to disturb the polymerization. To reduce the nucleophilicity of the eliminated anion, methyl ester of the monomer was changed to phenyl ester and its polymerization was studied. The reaction conditions were optimized, and the best result was obtained when the polymerization was conducted in the presence of 1.0 equivalent of LiHMDS without additives in THF at 50 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2365–2372     

Changes in superstructure and mechanical properties of poly(ethylene‐2,6‐naphthalate) fibers with critical necking tension

Poly(ethylene‐2,6‐naphthalate) fibers were zone‐drawn under a critical necking tension (σ_c) defined as the minimum tension needed to generate a necking at a given drawing temperature (T_d). In the zone drawing under σ_c, the neck was observed from 110 to 160 °C. The superstructure in a neck zone induced at each T_d was studied. The σ_c value decreased exponentially with increasing T_d and dropped to a low level at a higher T_d. The draw ratio increased rapidly with T_d increasing above 90 °C, but the birefringence and degree of crystallinity decreased gradually. To study the molecular orientation in the neck zone, we measured a dichroic ratio (A_‖/A_?) of a C? O band at 1256 cm^?1 along a drawing direction in the neck zone with a Fourier transform infrared microscope. A_‖/A_? at T_d = 110 °C increased rapidly in the narrow neck zone, and that at T_d = 140 °C increased in the edge of the wide neck zone. Wide‐angle X‐ray diffraction patterns of the fibers obtained at T_d = 130 °C and lower showed three reflections due to an α form, but those at T_d = 140 and 150 °C had reflections due to the α form and a β form. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1629–1637, 2001     

Cross-coupling reaction of chloropyrazines with ethylenes

Various chloropyrazines and their N-oxides were submitted to the cross-coupling reaction with ethylenes, such as styrene, ethyl acrylate and acrylonitrile. While the chloro-phenylpyrazines and 2-chloropyrazine 1-oxides were slugglish in this reaction system, the expected products were obtained from almost all the 2-chloro-3,6-dialkylpyrazines and their 4-oxides in moderate to good yields.     

20 beta-hydroxysteroid dehydrogenase of neonatal pig testis: reverse catalytic (oxidation) reaction

Neonatal pig testicular 20 beta-hydroxysteroid dehydrogenase (20 beta-HSD) catalyzed the oxidation of 20 beta-hydroxysteroids, 17 alpha,20 beta-dihydroxypregn-4-en-3-one and 20 beta-hydroxypregn-4-en-3-one in the presence of beta-nicotinamide adenine dinucleotide phosphate (beta-NADP+). The behavior of 20 beta-HSD activity toward the substrate of 17 alpha,20 beta-dihydroxypregn-4-en-3-one differed from the catalytic reaction for 20 beta-hydroxypregn-4-en-3-one. The enzyme could catalyze not only 20 beta-hydroxysteroids but also 20 alpha-hydroxy-5-ene steroids, 20 alpha-hydroxypregn-5-en-3 beta-ol and 17 alpha,20 alpha-hydroxypregn-5-en-3 beta-ol with 22.1 and 8.7% of activity relative to 20 beta-hydroxypregn-4-en-3-one, respectively. The enzyme preferentially required beta-NADP+, and also utilized beta-nicotinamide adenine dinucleotide beta-NAD+ and beta-nicotinamide adenine dinucleotide 3'-phosphate (beta-3'-NADP+) nonspecifically as the cofactor. The optimum pH was observed at pH 7.5 with the substrate of 20 beta-hydroxypregn-4-en-3-one. The activation energies obtained from oxidation-reduction reactions of 20 beta-HSD for the substrate of 20 beta-hydroxypregn-4-en-3-one, progesterone and 17 alpha-hydroxyprogesterone were estimated at 13.8, 27.0 and 20.0 kcal/mol, respectively.     

Hamming graphs in Nomura algebras

Let A be an association scheme on q≥3 vertices. We show that the Bose-Mesner algebra of the generalized Hamming scheme H(n,A), for n?2, is not the Nomura algebra of any type II matrix.This result gives examples of formally self-dual Bose-Mesner algebras that are not the Nomura algebras of type II matrices.