Mechanical deformation and multiple thermal restoration of organic crystals: reversible multi-stage shape-changing effect with luminescence-color changes

Shape-memory materials can be mechanically deformed and subsequently reverse the deformation upon changing the temperature. Shape-memory materials have attracted considerable attention for basic research and industrial applications, and polymer and alloy shape-memory materials have been well studied; however, it is formidably challenging to develop functional shape-memory materials, such as materials with multi-stage and anisotropic shape changes and shape changes accompanied by changes in color and light emission. Here, we found a reversible multi-stage shape-changing effect after mechanical deformation in a molecular crystal induced by multi-step thermal phase transitions with reversible shape changes and luminescence-color changes. Using single-crystal structure and thermal analyses as well as mechanical property measurements, we found that the reversible multi-stage shape-changing effect was achieved by a combination of a twinning deformation and multi-step thermal phase transitions. The changes in the crystal shape and luminescence suggest novel strategies for imparting known shape-memory materials with additional functionalities.

A reversible multi-stage shape-changing material based on an organic crystalline material is presented. Intriguingly, the interconversion among the three different shapes is accompanied by changes of the luminescence color.     

5,11-Diazadibenzo[hi,qr]tetracene: Synthesis,Properties, and Reactivity toward Nucleophilic Reagents

5,11-Diazadibenzo[hi,qr]tetracene was synthesized as a new nitrogen-substituted polycyclic heteroaromatic compound by Pd-catalyzed cycloisomerization of an alkyne precursor followed by oxidative cyclization with bis(trifluoroacetoxy)iodobenzene. The substitution of imine-type nitrogen atoms significantly enhanced its electron-accepting character and facilitated the direct nucleophilic addition of arylamines under strongly basic conditions to afford the desired amino-substituted products. The introduction of amino groups induced a remarkable red-shift in their absorption spectra; the tetrasubstituted product exhibited intense near-infrared absorbing property. Furthermore, the π-electronic system, which includes a redox-active 1,4-diazabutadiene moiety, underwent reversible interconversion to its corresponding reduced form upon reduction with NaBH₄ and aerobic oxidation.     

Ab initio study of small acetonitrile cluster anions

Ab initio electronic structure calculations have been performed for (CH(3)CN)(2) (-) and (CH(3)CN)(3) (-) cluster anions using a diffuse basis set. We found both the dipole-bound structures and internal structures, where in the former structure an excess electron is mainly distributed on the surface of the cluster while an excess electron is internally trapped in the latter configuration. The optimized structures found for cluster anions were compared to those for neutral clusters. Potential-energy surfaces were also plotted as a function of appropriate internal coordinates in order to understand the interconversions of the optimized structures of clusters. The relative stabilities of the optimized confirmers have been discussed on the basis of the characteristics of these potential surfaces, relative energies, and electron vertical detachment energies.     

Combinatorial synthesis of MUC1 glycopeptides: polymer blotting facilitates chemical and enzymatic synthesis of highly complicated mucin glycopeptides

The chemoselective polymer blotting method allows for rapid and efficient synthesis of glycopeptides based on a "catch and release" strategy between solid-phase and water-soluble polymer supports. We have developed a heterobifunctional linker sensitive to glutamic acid specific protease (BLase). The general procedure consists of five steps, namely (i) the solid-phase synthesis of glycopeptide containing BLase sensitive linker, (ii) subsequent deprotections and the release of the glycopeptide from the resin, (iii) chemoselective blotting of the glycopeptide intermediates in the presence of water-soluble polymers with oxylamino functional groups, (iv) sugar elongations using glycosyltransferases, and (v) the release of target glycopeptides from the polymer platform by selective BLase promoted hydrolysis. The combined use of the solid-phase chemical syntheses of peptides and the enzymatic syntheses of carbohydrates on water-soluble polymers would greatly contribute to the production of complicated glycopeptide libraries, thereby enhancing applicative research. We report here a high-throughput synthetic system for the various types of MUC1 glycopeptides exhibiting a variety of sugar moieties. It is our belief that this concept will become part of the entrenched repertoire for the synthesis of biologically important glycopeptides on the basis of glycosyltransferase reactions in automated and combinatorial syntheses.     

A comparative study for elastic electron collisions on the isoelectronic CNN, NCN, and CCO radicals

In this work, we present a theoretical study on elastic electron collisions from three isoelectronic free radicals (CNN, NCN, and CCO) in the low incident energy range. More specifically, calculated differential, integral, and momentum transfer cross sections are reported in the 1-30 eV energy range. Calculations are performed in the static-exchange and static-exchange-polarization levels. The iterative Schwinger variational method is used to solve the scattering equations. Our study reveals that the calculated cross sections for the three targets are significantly different at incident energies below 10 eV. Above that energy, a remarkable similarity among the calculated results is seen.     

Synthesis of N3-substituted uridine and related pyrimidine nucleosides and their antinociceptive effects in mice

Seventy eight N(3)-substituted derivatives of uridine (1), thymidine (2), 2'-deoxyuridine (3), 6-azauridine (4), 2',3'-O-isopropylideneuridine (5), and arabinofuranosyluracil (6) were synthesized and their antinociceptive effects were evaluated. N(3)-(2',4'-Dimethoxyphenacyl)uridine (1l), N(3)-(2',4'-dimethoxyphenacyl)2'-deoxyuridine (3l), and N(3)-(2',5'-dimethoxyphenacyl)arabinofuranosyluracil (6m) possessed 93, 86, and 82% of the antinociceptive effects tested by hot plate, respectively. The antinociceptive effects of three derivatives were 5.8, 5.4, and 5.1-folds of the effect of N(3)-phenacyluridine (1h) (16%), respectively. The structure-activity relationship of N(3)-substituted pyrimidine nucleosides was also discussed.     

Effect of UV anneal on plasma CVD low-k film

Plasma-enhanced chemical vapor deposition (PE-CVD) low-dielectric (low-k) film was irradiated with ultra violet (UV) light of wavelength 172 nm to enhance mechanical strength and reduce dielectric constant (k value). The thickness measurement method for the UV annealed low-k film is discussed. The effects of UV irradiation on dielectric constant, shrinkage, stress, density, pore size, mechanical strength, and structure are clarified and the mechanism is discussed.     

A validated LC‐MS/MS method for the determination of canagliflozin,a sodium–glucose co‐transporter 2 (SGLT‐2) inhibitor,in a lower volume of rat plasma: application to pharmacokinetic studies in rats

Canagliflozin is a novel, orally selective inhibitor of sodium‐dependent glucose co‐transporter‐2 (SGLT2) for the treatment of patients with type 2 diabetes mellitus. In this study, a validated liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for the quantitative analysis of canagliflozin in a lower volume of rat plasma (0.1 mL) was established and applied to a pharmacokinetic study in rats. Following liquid–liquid extraction by tert‐butyl methyl ether, chromatographic separation of canagliflozin was performed on a Quicksorb ODS (2.1 mm i.d. × 150 mm, 5 µm size) using acetonitrile–0.1% formic acid (90:10, v/v) as the mobile phase at a flow rate of 0.2 mL/min. The detection was carried out using an API 3200 triple‐quadrupole mass spectrometer operating in the positive electrospray ionization mode. Selected ion monitoring transitions of m/z = 462.0 [M + NH₄]⁺ → 191.0 for canagliflozin and m/z = 451.2 [M + H]⁺ → 71.0 for empagliflozin (internal standard) were obtained. The validation of the method was investigated, and it was found to be of sufficient specificity, accuracy and precision. Canagliflozin in rat plasma was stable under the analytical conditions used. This validated method was successfully applied to assess the pharmacokinetics of canagliflozin in rats using 0.1 mL rat plasma. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of polystyenes with different stereoregularities by anionic polymerization

The stereoregularity of polystyrene prepared by anionic polymerization was determined by means of ¹³C-NMR spectroscopy. The stereoregularity changed with such polymerization conditions as catalyst, solvent, and temperature. Sodium naphthalene as catalyst gave a syndiotactic-rich polystyrene of 66–68% syndiotactic dyads independently of solvent and temperature, while potassium and cesium naphthalenes as catalyst produced polystyrenes with different stereoregularities ranging from syndiotactic-rich to isotactic-rich configurations, depending on solvent and temperature. The mechanism of anionic polymerization which caused the difference in stereoregularity was discussed from the viewpoint of growing ionic species.