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1.
Topological “interfacial” polymer chemistry: Dependency of polymer “shape” on surface morphology and stability of layer structures when heating organized molecular films of cyclic and linear block copolymers of n‐butyl acrylate‐ethylene oxide 下载免费PDF全文
Qi Meng Satoshi Honda Yasuyuki Tezuka Takuya Yamamoto Atsuhiro Fujimori 《Journal of Polymer Science.Polymer Physics》2016,54(4):486-498
The “topological polymer chemistry” of amphiphilic linear and cyclic block copolymers at an air/water interface was investigated. A cyclic copolymer and two linear copolymers (AB‐type diblock and ABA‐type triblock copolymers) synthesized from the same monomers were used in this study. Relatively stable monolayers of these three copolymers were observed to form at an air/water interface. Similar condensed‐phase temperature‐dependent behaviors were observed in surface pressure–area isotherms for these three monolayers. Molecular orientations at the air/water interface for the two linear block copolymers were similar to that of the cyclic block copolymer. Atomic force microscopic observations of transferred films for the three polymer types revealed the formation of monolayers with very similar morphologies at the mesoscopic scale at room temperature and constant compression speed. ABA‐type triblock linear copolymers adopted a fiber‐like surface morphology via two‐dimensional crystallization at low compression speeds. In contrast, the cyclic block copolymer formed a shapeless domain. Temperature‐controlled out‐of‐plane X‐ray diffraction (XRD) analysis of Langmuir–Blodgett (LB) films fabricated from both amphiphilic linear and cyclic block copolymers was performed to estimate the layer regularity at higher temperatures. Excellent heat‐resistant properties of organized molecular films created from the cyclic copolymer were confirmed. Both copolymer types showed clear diffraction peaks at room temperature, indicating the formation of highly ordered layer structures. However, the layer structures of the linear copolymers gradually disordered when heated. Conversely, the regularity of cyclic copolymer LB multilayers did not change with heating up to 50 °C. Higher‐order reflections (d002, d003) in the XRD patterns were also unchanged, indicative of a highly ordered structure. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 486–498 相似文献
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Ryo Nozawa Keitaro Yamamoto Prof. Dr. Ji‐Young Shin Prof. Dr. Satoru Hiroto Prof. Dr. Hiroshi Shinokubo 《Angewandte Chemie (International ed. in English)》2015,54(29):8454-8457
Treatment of antiaromatic nickel(II) norcorrole with potassium cyanide provided nickel(II) 3‐cyanonorcorrole with perfect regioselectivity without the help of a catalyst. The reaction of the nickel(II) norcorrole with phenol or thiophenol in the presence of a base also yielded substitution products. The antiaromatic 16π conjugation system in the norcorrole core was preserved in the functionalized products. Introduction of phenylthio groups significantly decreased the HOMO–LUMO gap and enhanced the near IR absorption property. 相似文献
4.
Hiromi NAKANISHI Atsushi MORI Kouki TAKEDA Houdo TANAKA Natsuko KOBAYASHI Keitaro TANOI Takashi YAMAKAWA Satoshi MORI 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(4):160-174
Six months after the explosion of TEPCO’s Fukushima Dai-ichi nuclear power plant, radioactive
silver (110mAg), was detected in concentrations of 3754 Bq/kg in Nephila
clavata (the orb-web spider; Joro-gumo in Japanese) collected at
Nimaibashi, Iitate village in Fukushima Prefecture, whereas 110mAg in the soil was
43.1 Bq/kg. A survey of 35 faunal species in the terrestrial environment during the 3.5 years
after the accident showed that most of Anthropoda had two orders higher 110mAg in
their tissues than soils, although silver is not an essential element for their life. However,
tracing of the activity of 110mAg detected in spider Atypus karschi
collected regularly at a fixed location showed that it declined much faster than the physical
half-life. These results suggest that 110mAg was at once biologically concentrated
by faunal species, especially Arthropoda, through food chain. The factors affecting the
subsequent rapid decline of 110mAg concentration in faunal species are
discussed. 相似文献
5.
Sujoy Bandyopadhyay Rmi Mtivier Pragyan Pallavi Eduard Preis Keitaro Nakatani Katharina Landfester Abhijit Patra Ullrich Scherf 《Macromolecular rapid communications》2016,37(3):271-277
Conjugated polymer nanoparticles based on poly[9,9‐bis(2‐ethylhexyl)fluorene] and poly[N‐(2,4,6‐trimethylphenyl)‐N,N‐diphenylamine)‐4,4′‐diyl] are fabricated using anionic surfactant sodium dodecylsulphate in water by miniemulsion technique. Average diameters of polyfluorene and polytriarylamine nanoparticles range from 70 to 100 and 100 to 140 nm, respectively. The surface of the nanoparticles is decorated with triplet emitting dye, tris(2,2′‐bipyridyl)ruthenium(II) chloride. Intriguing photophysics of aqueous dispersions of these hybrid nanoparticles is investigated. Nearly 50% quenching of fluorescence is observed in the case of dye‐coated polyfluorene nanoparticles; excitation energy transfer is found to be the dominant quenching mechanism. On the other hand, nearly complete quenching of emission is noticed in polytriarylamine nanoparticle‐dye hybrids. It is proposed that the excited state electron transfer from the electron‐rich polytriarylamine donor polymer to Ru complex leads to the complete quenching of emission of polytriarylamine nanoparticles. The current study offers promising avenues for developing aqueous solution processed‐electroluminescent devices involving a conjugated polymer nanoparticle host and Ru or Ir‐based triplet emitting dye as the guest.
6.
Prof. Shingo Saito Toshiki Sakamoto Naoki Tanaka Ryo Watanabe Takuya Kamimura Kazuki Ota Kathryn R. Riley Keitaro Yoshimoto Yuiko Tasaki-Handa Masami Shibukawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(39):10058-10067
In DNA aptamer selection, existing methods do not discriminate aptamer sequences based on their binding affinity and function and the reproducibility of the selection is often poor, even for the selection of well-known aptamers like those that bind the commonly used model protein thrombin. In the present study, a novel single-round selection method (SR-CE selection) was developed by combining capillary electrophoresis (CE) with next generation sequencing. Using SR-CE selection, a successful semi-quantitative and semi-comprehensive aptamer selection for thrombin was demonstrated with high reproducibility for the first time. Selection rules based on dissociation equilibria and kinetics were devised to obtain families of analogous sequences. Selected sequences of the same family were shown to bind thrombin with high affinity. Furthermore, data acquired from SR-CE selection was mined by creating sub-libraries that were categorized by the functionality of the aptamers (e. g., pre-organized aptamers versus structure-induced aptamers). Using this approach, a novel fluorescent molecular recognition sensor for thrombin with nanomolar detection limits was discovered. Thus, in this proof-of-concept report, we have demonstrated the potential of a “DNA Aptaomics” approach to systematically design functional aptamers as well as to obtain high affinity aptamers. 相似文献
7.
Dr. Juliette Guérin Dr. Anne Léaustic Prof. Stéphanie Delbaere Dr. Jérôme Berthet Dr. Régis Guillot Dr. Cyril Ruckebusch Dr. Rémi Métivier Prof. Keitaro Nakatani Dr. Maylis Orio Dr. Michel Sliwa Dr. Pei Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12279-12288
A terthiazole‐based molecular switch associating 6π electrocyclization, excited state intramolecular proton transfer (ESIPT), and strong metal binding capability was prepared. The photochemical and photophysical properties of this molecule and of the corresponding nickel and copper complexes were thoroughly investigated by steady‐state and ultrafast absorption spectroscopy and rationalized by DFT/TDDFT calculations. The switch behaves as a biphotochrome with time‐dependent photochemical outcome and displays efficient ESIPT‐based fluorescence photoswitching. Both photochemical reactions are suppressed by nickel or copper metalation, and the main factors contributing to the quenching of the electrocyclization are discussed. 相似文献
8.
Yusuke Imai Atsushi Terahara Keitaro Matsui Nobuhiko Ueno 《European Polymer Journal》2009,45(3):630-3519
Transparent organic-inorganic nanocomposites were successfully synthesized from sulfonic acid-modified poly(bisphenol A carbonate) (SPC) and TiO2 or ZrO2 nanoparticles. The dispersibility of nanoparticles was significantly improved by both the surface treatment of nanoparticles with phosphoric acid 2-ethylhexyl esters (PAEH) and the introduction of a sulfonic acid moiety into the PC chain. It was found that in some cases, crystallization of the matrix caused a reduction in transparency. Efficient dispersion of nanoparticles and the absence of crystallization resulted in highly transparent nanocomposites with up to 42 wt% TiO2 and 50 wt% ZrO2 nanoparticles. The refractive indices of the nanocomposites based on SPC increased with the increasing amount of nanoparticles. Theoretical equation based on Maxwell-Garnett effective medium theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The prepared nanocomposites had lower thermal stability than the host matrix polymers. 相似文献
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Zircon-type compounds LnCrO4 (Ln=Nd, Sm, and Dy) were prepared. Their precise crystal structures at room temperature were determined from X-ray diffraction measurements. These compounds have a tetragonal system with space group I41/amd. Magnetic susceptibility and specific heat measurements have been performed for all the compounds in the temperature range between 1.8 and 300 K. For NdCrO4, an antiferromagnetic transition was found at 25.2 K. SmCrO4 and DyCrO4 show magnetic transitions at 15.0 and 22.8 K, respectively. In addition, structural phase transitions were observed at 58.5 and 31.2 K, respectively. For DyCrO4, the crystal structure below the transition temperature was determined by low-temperature powder X-ray diffraction measurements to be orthorhombic with space group Imma. 相似文献