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101.
Nobuyuki Otozawa Rio Hamajima Masataka Yoshioka Raito Kato Arisa Tanaka Hiroto Fukuma Toshiki Terao Kei Manabe Syuji Fujii Yoshinobu Nakamura Atsushi Takahara Tomoyasu Hirai 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1960-1964
This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using 1H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA. 相似文献
102.
103.
Kumagai Yuta Kimura Atsushi Taguchi Mitsumasa Watanabe Masayuki 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):341-348
Journal of Radioanalytical and Nuclear Chemistry - This study aims to demonstrate that zeolite has the potential to increase the efficiency of radiolysis treatment of aqueous organic pollutants by... 相似文献
104.
Partially bio‐based tri‐ and hexaallyl monomers: Synthesis from naturally occurring myo‐inositol and polyaddition with dithiols 下载免费PDF全文
Atsushi Sudo Yugo Shirakawa Tomio Sakue 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1524-1529
myo‐Inositol, a naturally occurring cyclic hexaol, was converted to 2,4,6‐tri‐O‐allyl‐myo‐inositol and 1,2,3,4,5,6‐hexa‐O‐allyl‐myo‐inositol. Polyaddition of the former product, a tri(allyl ether) bearing three hydroxyl groups, with dithiols yielded the corresponding networked polymers. Their glass transition temperatures (Tgs) were higher than those of networked polymers formed by the polyaddition of 1,3,5‐tri‐O‐methyl‐2,4,6‐tri‐O‐allyl‐myo‐inositol. This implied the reinforcement of the networks by hydrogen bonding between the hydroxyl groups. Polyaddition of the latter product, a hexa(allyl ether), with dithiols yielded the corresponding networked polymers with much higher Tgs than those of all of the aforementioned networked polymers. This implied that efficient use of the hexafunctional monomer leads to the formation of more densely crosslinked polymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1524–1529 相似文献
105.
Asei William Kawaguchi Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(3):410-416
1,3‐benzoxazine 1 , bearing 4‐pyridyl moiety on the nitrogen atom, was synthesized from p‐cresol, 4‐aminopyridine, and paraformaldehyde. The efficient synthesis was achieved by adding acetic acid to suppress the strong basicity caused by the presence of 4‐aminopyridine derivatives. Upon heating 1 at 180 °C, it underwent the thermally induced ring‐opening polymerization. The resulting polymer was composed of two types of repeating unit, i.e., (1) Mannich‐type one (‐phenol‐CH2‐NR‐CH2‐) that can be expected from the general ring‐opening polymerization of conventional benzoxazines and (2) a typical phenolic resin‐type one (‐phenol‐CH2‐phenol‐) induced by release of 4‐aminopyridine and paraformaldehyde (unit B). Another structural feature of the polymer was that it possessed a benzoxazine moiety at the chain end. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 410–416 相似文献
106.
Dual Chemical Modification of a Polytheonamide Mimic: Rational Design and Synthesis of Ion‐Channel‐Forming 48‐mer Peptides with Potent Cytotoxicity 下载免费PDF全文
Atsushi Hayata Dr. Hiroaki Itoh Shoko Matsutaka Prof.Dr. Masayuki Inoue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3370-3377
Polytheonamide B ( 1 ) is a natural peptide that displays potent cytotoxicity against P388 mouse leukemia cells (IC50=0.098 nm ). Linear 48‐mer 1 is known to form monovalent cation channels on binding to lipid bilayers. We previously developed a fully synthetic route to 1 , and then achieved the design and synthesis of a structurally simplified analogue of 1 , namely, dansylated polytheonamide mimic 2 . Although the synthetically more accessible 2 was found to emulate the channel function of 1 , its cytotoxicity was decreased 120‐fold. Herein, the chemical preparation and biological evaluation of seven analogues 3 – 9 of 2 are reported. Compounds 3 – 9 were modified at their N terminus and/or the side chain of residue 44 of 2 to alter their physicochemical properties. The total synthesis of 3 – 9 was accomplished in a unified fashion by a combination of solid‐phase and solution‐phase chemistry. Systematic evaluation of the hydrophobicities, single‐channel currents, ion‐exchange activities, and cytotoxicities of 3 – 9 revealed that their hydrophobicities are correlated with the total magnitude of ion exchange and determine their cytotoxic potency. Consequently, the most hydrophobic analogue 9 exhibited the lowest IC50 value, which is comparable to that of 1 . Therefore, these results clarified that the bioactivity of the polytheonamide‐based peptides can be rationally controlled by changing their hydrophobicity at the N and C termini of the 48‐amino‐acid sequence. 相似文献
107.
Atsushi Yashiro Dr. Yuya Tanaka Prof. Tomofumi Tada Prof. Shintaro Fujii Prof. Tomoaki Nishino Prof. Munetaka Akita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(37):9666-9673
In this work, the design, synthesis, and single-molecule conductance of ethynyl- and butadiynyl-ruthenium molecular wires with thioether anchor groups [RS=n-C6H13S, p-tert-Bu−C6H4S), trans-{RS−(C≡C)n}2Ru(dppe)2 (n=1 ( 1R ), 2 ( 2R ); dppe: 1,2-bis(diphenylphosphino)ethane) and trans-(n-C6H13S−C≡C)2Ru{P(OMe)3}4 3hex ] are reported. Scanning tunneling microscope break-junction study has revealed conductance of the organometallic molecular wires with the thioacetylene backbones higher than that of the related organometallic wires having arylethynylruthenium linkages with the sulfur anchor groups, trans-{p-MeS−C6H4-(C≡C)n}2Ru(phosphine)4 4 n (n=1, 2) and trans-(Th−C≡C)2Ru(phosphine)4 5 (Th=3-thienyl). It should be noted that the molecular junctions constructed from the butadiynyl wire 2R , trans-{ Au −RS−(C≡C)2}2Ru(dppe)2 ( Au : gold metal electrode), show conductance comparable to that of the covalently linked polyynyl wire with the similar molecular length, trans-{ Au −(C≡C)3}2Ru(dppe)2 63 . The DFT non-equilibrium Green's function (NEGF) study supports the highly conducting nature of the thioacetylene molecular wires through HOMO orbitals. 相似文献
108.
Abstract In this study, the formation of polyion complex micelles from a pair of poly(L-lysine) homopolymers (P(Lys)) and poly(ethylene glycol)-poly(aspartic acid) block copolymers (PEG-P(Asp)) with varying chain length was demonstrated in aqueous medium. There exists the lower critical chain length in the charged segments of both P(Lys) and PEG-P(Asp) to form stable polyion complex micelles in nanometric scale. The scaled average characteristic line width (ΓTK2) was independent on the detection angles for all combinations, suggesting that the formed polyion complex micelles may have a spherical shape. Furthermore, the transitional diffusion coefficient (DT) had no concentration dependence, indicating the micelle system was free from secondary aggregates (the cluster of micelles). It is of interest that the micellar size was almost constant (ca. 50 nm) regardless of the change in the chain length of the charged segments. Size distribution was extremely narrow, and the values of variance μ2/Γ 2) were always less than 0.1. Laser-Doppler electrophoresis measurements revealed that the polyion complex micelles were electrically neutral, suggesting that the PEG corona surrounding the polyion complex core may contribute to their stable dispersion in an aqueous medium through steric repulsion of the tethered hydrophilic chain, in this case, PEG. This system was considerably stable against the change in ionic strength, and it maintained a constant diameter in the region below 0.4 M NaCl. However, they dissociated under high ionic strength condition as 0.6 M NaCl. The system may have potential utility to include charged peptides and nucleotides in the core, delivering these biologically useful substances into a target site in the body. 相似文献
109.
110.
Selective and very convenient methods of iodination of calix[4]arenes using ICl or NIS have been demonstrated, preparing mono(p-iodo) and 1,3-di(p-iodo) derivatives of calix[4]arenecrown-4 and -5, as well as mono(p-iodo) derivative of tris(O-propyl)calix[4]arene in good yields. 相似文献