Photoremovable NPEC group compatible with Ns protecting group in polyamine synthesis

Herein, we disclose an efficient combination of NPEC and Ns protecting groups in the synthesis of polyamine, by showing the orthogonal reactivity using N-NPEC-N-Ns alkylamines prepared from NPEC-NHNs. Selective photodeprotection of NPEC group in 12-mer polyamine and the complex conjugate has been further demonstrated toward the synthesis of novel polyamine natural product protoaculeine B.     

Reversible micelle-vesicle conversion of oleyldimethylamine oxide by pH changes

A preliminary study on the reversible micelle-vesicle conversion of oleyldimethylamine oxide [Kawasaki, H. et al. J. Phys. Chem. B. 2002, 106, 1524 ] is extended in the present study. In the presence of 0.01 M NaCl at a surfactant concentration of 0.05 M, a micelle-to-vesicle conversion with increasing degree of ionization alpha takes place in the following sequence: growth of fibrous micelle (alpha < 0.2), a fused network (alpha approximately 0.3), fibrous micelles + (perforated) vesicles (alpha = 0.4), and vesicles + lamellae (alpha = 0.5). Viscoelasticity correspondingly varies from the Maxwell-type behavior of the entangled network of fibrous micelles to the gel-like behavior of vesicle suspensions, via a fluid solution-like behavior of the fused network. This phase sequence is in contrast with the case of no added salt where no branching of micelles is observed, and long micelles and bilayers (vesicles + lamellae) coexist at alpha = 0.5. In water, a state of the lowest viscoelasticity occurs around alpha = 0.2 for both surfactant concentrations 0.05 and 0.15 M. Synergism between protonated and nonprotonated amine oxide headgroups is observed despite low ionic strengths. From the time course of the reversible micelle-vesicle conversion, vesicles seem to be formed from threadlike micelles within 25 h according to the shear moduli, while a longer conversion time is suggested by a flow property (viscosity). Shear thickening behavior is observed at alpha = 0.2 and 0.4 in 0.01 M NaCl but not in water.     

Fundamental properties of a touchable high‐power pulsed microplasma jet and its application as a desorption/ionization source for ambient mass spectrometry

Plasma‐based ambient desorption/ionization mass spectrometry (ADI–MS) has attracted considerable attention in many fields because of its capacity for direct sample analyses. In this study, a high‐power pulsed microplasma jet (HPPMJ) was developed and investigated as a new plasma desorption/ionization source. In an HPPMJ, a microhollow cathode discharge is generated in a small hole (500 µm in diameter) using a pulsed high‐power supply. This system can realize a maximum power density of 5 × 10⁸ W/cm³. The measured electron number density, excitation temperature and afterglow gas temperature of the HPPMJ were 3.7 × 10¹⁵ cm^‐3, 7000 K at maximum and less than 60 °C, respectively, which demonstrate that the HPPMJ is a high‐energy, high‐density plasma source that is comparable with an argon inductively coupled plasma while maintaining a low gas temperature. The HPPMJ causes no observable damage to the target because of its low gas temperature and electrode configuration; thus, we can apply it directly to human skin. To demonstrate the analytical capacity of ADI–MS using an HPPMJ, the plasma was applied to direct solid sample analysis of the active ingredients in pharmaceutical tablets. Caffeine, acetaminophen, ethenzamide, isopropylantipyrine and ibuprofen were successfully detected. Application to living tissue was also demonstrated, and isopropylantipyrine on a finger was successfully analyzed without damaging the skin. The limits of detection (LODs) for caffeine, isopropylantipyrine and ethenzamide were calculated, and LODs at the picogram level were achieved. These results indicate the applicability of the HPPMJ for high‐sensitivity analysis of materials on a heat‐sensitive surface. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of iron—cobalt ultrafine particles by decomposition of Fe(CO)5---Co(CO)3NO using a TEA CO2 laser

Ultrafine particles of iron—cobalt alloy were synthesized and isolated at room temperature in a maximum yield of 90% by the dielectric breakdown of a mixture of Fe(CO)₅ (5 Torr) and Co(CO)₃NO (0.5 Torr) on irradiation with a tightly-focused laser beam of a transversely-excited-atmospheric (TEA) CO₂ laser. CO and NO are also obtained as volatile products. Transmission electron micrographs of the iron-cobalt particles show the existence of fine and well-organized spherical particles. The distribution of the particle size is relatively uniform in the range 6–9 nm with a mean particle size of 8 nm. In X-ray diffractometry, the ultrafine particles are found to be mainly f.c.c. γ-iron—cobalt alloy which is normally stable in the range 1183–1234 K to 1673–1773 K. The b.c.c. -iron—cobalt, iron oxides and cobalt oxides are observed as minor products (γ-iron—cobalt to iron---cobalt OXIDES=8:1:1). The ratio of iron and cobalt atoms in the particles can be changed by changing the mixture of Fe(CO)₅ and Co(CO)₃NO. The ratio of γ-iron—cobalt to -iron—cobalt to iron—cobalt oxide also depends on the ratio of iron and cobalt atoms in the particles.     

Wide-bore capillary hydrodynamic chromatography with ICP-MS detection for evaluation of lanthanide uptake by molecular aggregates

Wide-bore capillary hydrodynamic chromatography (W-HDC) resolves analytes on the basis of a difference in the extent of radial diffusion simply by their passage through an empty capillary. The combination of this method with ICP-MS proves efficient for the evaluation of the interaction of metal ions with molecular aggregates. Lecithin vesicles are suitable molecular aggregates for the uptake of the lanthanide ions in the presence of the first row transition metal ions, suggesting that the present method is applicable to the screening of the molecular aggregate system suitable for selective extraction of a particular targeted small molecule. The visual inspection of the elution profiles gives us qualitative but useful information on the interaction between the vesicle and metal ions. In addition, studying the slope of the front edge of an elution curve provides more quantitative implications.     

Biomolecular embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 degrees C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate).     

Crystal Structure and Structural Transformation of [(CH3)3NH]2[CuZn(CN)5]

A newly synthesized coordination polymer, [(CH₃)₃NH]₂[CuZn(CN)₅], was investigated using ¹³C and ⁶³Cu solid‐state NMR techniques and single‐crystal X‐ray diffractometry. It consists of a three‐dimensional (3D) net composed of tetrahedral Cu^I and Zn^II ions and CN^– ligands bridging between the two metal ions. (CH₃)₃NH⁺ ions are trapped in the inner space of the 3D net. Three coordination sites of each metal ion are used for the formation of the 3D net and the remaining site is occupied by a unidentate CN^– ligand. The structure of the 3D net is chiral and categorized as srs in the notation of the Reticular Chemistry Structure Resource (RCSR). In water vapor or open air at room temperature under ambient pressure, a powder of [(CH₃)₃NH]₂[CuZn(CN)₅] showed a structural transformation to [(CH₃)₃NH][CuZn(CN)₄] · 1.5H₂O, which is a known compound with a diamond‐like 3D net of [CuZn(CN)₄]^– composed of tetrahedral Cu^I and Zn^II ions and bridging CN^– ligands. ⁶³Cu solid‐state NMR spectroscopy revealed that the Cu‐CN‐Zn orientation of the bridging CN^– ligands was conserved after the structural transformation.     

Electrooxidative glycosylation through C-S bond cleavage of 1-arylthio-2,3-dideoxyglycosides. Synthesis of 2',3'-dideoxynucleosides

[reaction: see text] The electrooxidative glycosylation of newly designed 1-arylthio-substituted 2,3-dideoxyglycosides is described. The halide salt-mediated electrooxidation utilizing either of the alpha- or beta-thiodideoxyglycosides proceeded smoothly at -78 degrees C to give dideoxynucleosides in a beta-selective manner, presumably through a 1-halo-substituted glycosyl donor.