Carbazolyl Benzo[1,2‐b:4,5‐b′]difuran: An Ambipolar Host Material for Full‐Color Organic Light‐Emitting Diodes

We have designed an ambipolar material, 3,7‐bis[4‐(N‐carbazolyl)‐phenyl]‐2,6‐diphenylbenzo[1,2‐b:4,5‐b′]difuran (CZBDF), and synthesized it by zinc‐mediated double cyclization. Its physical properties clarified that CZBDF possesses a wide‐gap character, well‐balanced and high hole and electron mobilities of larger than 10^?3 cm² V^?1 s^?1, and a high thermal stability. Using CZBDF as a host material for heterojunction OLED devices, a full range of visible emission was obtained. Notably, CZBDF also enabled us to fabricate RGB‐emitting homojunction OLEDs, with performances comparable or superior to the heterojunction devices composed of several materials.     

Synthesis and Characterization of Stereo Multiblock Poly(lactic acid)s with Different Block Lengths by Melt Polycondensation of Poly(L‐lactic acid)/Poly(D‐lactic acid) Blends

Stereo multiblock PLAs with different block lengths are synthesized by melt polycondensation of low‐molecular‐weight poly(L ‐lactic acid)/poly(D ‐lactic acid) blends with a wide variety of $\overline {M} _{{\rm w}} $ in the range of 1.1–5.2 × 10³ g · mol^–1. The average block length (ν_av) of the stereo multiblock PLAs increases with increasing $\overline {M} _{{\rm w}} $ of the blend and with the reaction temperature, whereas $\overline {M} _{{\rm w}} $ and PDI of the stereo multiblock PLAs increases with increasing $\overline {M} _{{\rm w}} $ of the blend, the reaction time, and the temperature. Stereo multiblock PLAs with ν_av > 7 are crystallizable to form stereocomplex crystallites, and the crystallinity and melting temperature of the stereo multiblock PLAs increases with increasing ν_av and $\overline {M} _{{\rm w}} $ of the stereo multiblock PLAs.

     

Incompatibility between Propericiazine Oral Solution and Tea-Based Drink

Here, we studied the incompatibility between an oral solution of propericiazine (PCZ), an antipsychotic drug, and various commercially available bottled tea-based drinks. When 0.5?mL of the PCZ oral solution (10?mg/mL) was mixed with 16.5?mL of a tea-based drink (such as green tea, oolong tea, and black tea), the residual PCZ content declined to approximately 50% in some mixed solutions. After mixing with other tea-based drinks, the residual PCZ content declined to approximately 30%, while in others, it changed very little. The residual PCZ content declined immediately after mixing with tea-based drinks, but the rate remained almost unchanged for the next 24?h. Furthermore, the pH of the mixture increased to 4.5-5.1 after the oral solution of PCZ (original pH 3.8) was diluted with various tea-based drinks. Afterwards, the pH did not change for 24?h. The mixture became cloudy immediately after diluting PCZ oral solution with tea-based drinks, and the insoluble substance gradually precipitated. In order to elucidate factors responsible for the decline in the content of PCZ, a (-)-epigallocatechin gallate solution, which is a main ingredient of green tea polyphenol, was mixed with the PCZ oral solution. After mixing, the residual PCZ content declined to approximately 60-75%. On the other hand, the content of PCZ did not decline when a (-)-epigallocatechin solution was mixed with the PCZ oral solution. The results from this study demonstrated that PCZ content was reduced after dilution in tea-based drinks because of the interaction between PCZ and polyphenol with a galloyl group in tea-based drinks.     

Excited state hydrogen transfer in fluorophenol.ammonia clusters studied by two-color REMPI spectroscopy

Two-color (1 + 1') REMPI mass spectra of o-, m- and p-fluorophenol.ammonia (1 ration) clusters were measured with a long delay time between excitation and ionization lasers. The appearance of NH(4)(NH(3))(n-1)(+) with 100 ns delay after exciting the S(1) state is a strong indication of generation of long-lived species via S(1). In analogy with the phenol.ammonia clusters, we conclude that an excited state hydrogen transfer reaction occurs in o-, m- and p-fluorophenol.ammonia clusters. The S(1)-S(0) transition of o-, m- and p-fluorophenol.ammonia (1 : 1) clusters were measured by the (1 + 1') REMPI spectra, while larger (1 ration) cluster (n = 2-4) were observed by monitoring the long-lived NH(4)(NH(3))(n-1) clusters action spectra. The vibronic structures of m- and p-fluorophenol.ammonia clusters are assigned based on vibrational calculations in S(0). The o-fluorophenol.ammonia (1 : 1) cluster shows an anharmonic progression that is analyzed by a one-dimensional internal rotational motion of the ammonia molecule. The interaction between the ammonia molecule and the fluorine atom, and its change upon electronic excitation are suggested. The broad action spectra observed for the o-fluorophenol.ammonia (1 : n) cluster (n>== 2) suggest the excited state hydrogen transfer is faster than in m- and p-fluorophenol.ammonia clusters. The different reaction rates between o-, m- and p-fluorophenol.ammonia clusters are found from comparison between the REMPI and action spectra.     

Crystallization behaviors of poly(3-hydroxybutyrate) and poly(l-lactic acid) in their immiscible and miscible blends

By adjusting the molecular weight of the poly(l-lactic acid) (PLLA) component in poly(3-hydroxybutyrate) (PHB)/PLLA blends, we investigated the crystallization behaviors of the two components in their immiscible and miscible 50:50 blends by real time infrared (IR) spectroscopy. In the immiscible PHB/PLLA blend, the stepwise crystallization of PHB and PLLA was realized at different crystallization temperatures. PLLA crystallizes first at a higher temperature (120 degrees C). Its crystallization mechanism from the immiscible PHB/PLLA melt is not affected by the presence of the PHB component, while its crystallization rate is substantially depressed. Subsequently, in the presence of crystallized PLLA, the isothermal melt-crystallization of PHB takes place at a lower temperature (90 degrees C). It is interesting to find that there are two growth stages for PHB. At the early stage of the growth period, the Avrami exponent is 5.0, which is unusually high, while in the late stage, it is 2.5, which is very close to the reported value (n approximately 2.5) for the neat PHB system. In contrast to the stepwise crystallization of PHB and PLLA in the immiscible blends, the almost simultaneous crystallization of PHB and PLLA in the miscible 50:50 blend was observed at the same crystallization temperature (110 degrees C). Detailed dynamic analysis by IR spectroscopy has disclosed that, even in such apparently simultaneous crystallization, the crystallization of PLLA actually occurs faster than that of PHB. It has been found that, both in the immiscible and miscible blends, the crystallization dynamics of PHB are heavily affected by the presence of crystallized PLLA.     

When does an intermediate become a transition state? Degenerate isomerization without competing racemization during solvolysis of (S)-1-(3-nitrophenyl)ethyl tosylate

(S)-1-(3-Nitrophenyl)ethyl tosylate [(S)-2-OTs] was prepared in >99% enantiomeric excess and the change in the chiral purity of this compound was monitored during solvolysis in 50:50 trifluoroethanol/water. The barely detectable formation of 0.5% (R)-2-OTs after two half times for the solvolysis reaction was used to calculate a rate constant of k(rac) approximately equal to 4 x 10-6 s-1. This is 80-fold smaller than kiso = 3.2 x 10-4 s-1 for the isomerization that exchanges oxygen-16 and oxygen-18 of 3-NO2C6H413CH(Me)OS(18O)2Tos during solvolysis and 10-fold smaller than the minimum value of k(rac) = 4.6 x 10-5 s-1 predicted if isomerization and racemization products form by partitioning of a common ion-pair intermediate of a stepwise reaction. It is concluded that the isomerization reaction proceeds mainly by a pathway that avoids formation of this putative intermediate. It is suggested that the solvolysis reaction of 2-OTs may proceed by a stepwise preassociation mechanism where solvent "reorganization" precedes substrate ionization to form an ion-pair intermediate.     

Evaluation of bitterness suppression of macrolide dry syrups by jellies

The purpose of this study was to evaluate the bitterness-suppressing effect of three jellies, all commercially available on the Japanese market as swallowing aids, on two dry syrups containing the macrolides clarithromycin (CAM) or azithromycin (AZM). The bitterness intensities of mixtures of the dry syrups and acidic jellies were significantly greater than those of water suspensions of the dry syrups in human gustatory sensation tests. On the other hand, the mixture with a chocolate jelly, which has a neutral pH, was less bitter than water suspensions of the dry syrups. The bitterness intensities predicted by the taste sensor output values correlated well with the observed bitterness intensities in human gustatory sensation tests. When the concentrations of CAM and AZM in solutions extracted from physical mixtures of dry syrup and jelly were determined by HPLC, concentrations in the solutions extracted from mixtures with acidic jellies were higher than those from mixtures with a neutral jelly (almost 90 times higher for CAM, and almost 7-10 times higher for AZM). Thus, bitterness suppression is correlated with the pH of the jelly. Finally, a drug dissolution test for dry syrup with and without jelly was performed using the paddle method. There was no significance difference in dissolution profile. It was concluded the appropriate choice of jelly with the right pH is essential for taste masking. Suitable jellies might be used to improve patient compliance, especially in children. The taste sensor may be used to predict the bitterness-suppressing effect of the jelly.     

Preparation of Polymer-Supported Chiral 1,2-Diamine as an Efficient Ligand for Asymmetric Hydrogenation Catalyst

An enantiopure 1,2-diamine having two phenolic hydroxy groups was synthesized, and attached to chloromethylated poly(styrene) through a benzyl ether linkage. The polymer-supported Ru precatalysts were prepared from the polymeric chiral 1,2-diamine and RuCl₂/BINAP complex. In the presence of t-BuOK the polymeric catalyst system worked well in asymmetric hydrogenation of aromatic ketones in a mixed solvent of 2-propanol and DMF. The insoluble polymeric catalyst was readily separated from the reaction mixture and reused at least several times without loss of the catalytic activity.