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81.
Takakazu Yamamoto Takuma Yasuda Yoshimasa Sakai Shinji Aramaki 《Macromolecular rapid communications》2005,26(15):1214-1217
Summary: A π‐conjugated charge transfer‐type copolymer consisting of an electron‐donating thiophene and an electron‐accepting 1,3,4‐thiadiazole, P(ThdzTh), underwent facile electrochemical p‐ and n‐doping, as revealed by cyclic voltammetry. The copolymer gave a new ambipolar field‐effect transistor (FET), which showed typical IDS (source–drain current)–VDS (source–drain voltage) curves in both a p‐type working mode and an n‐type working mode. In the n‐type working mode, the polymer showed a carrier mobility of about 5 × 10−3 cm2 · V−1 · s−1 and an on/off ratio of about 3 × 104.
82.
Yamamoto T Lee BL Nurulla I Yasuda T Yamaguchi I Wada A Hirose C Tasumi M Sakamoto A Kobayashi E 《The journal of physical chemistry. B》2005,109(21):10605-10610
Two types of energy transfer in pi-conjugated polymers have been investigated using time-resolved photoluminescence (PL) techniques: type i, perpendicular-type energy transfer from the 2,3-di(p-tolyl)quinoxaline unit to the pi-conjugated main chain of poly[2,3-di(p-tolyl)quinoxaline-5,8-diyl], and type ii, parallel-type energy transfer from the oligo(pyridine-2,5-diyl) (O-Py) unit to the oligo(selenophene-2,5-diyl) (O-Se) unit in a block-type copolymer of O-Py and O-Se. Both types of energy transfer were very fast with a time constant shorter than approximately 0.1 ns; in particular, the type ii energy transfer took place with a time constant of approximately 5 ps. Both pi-conjugated polymers were considered to contain segments with various effective pi-conjugation lengths, and the energy transfer to the segment with a larger effective pi-conjugation length and a smaller pi-pi* transition energy required a longer transition time. A polarizing film was obtained by utilizing the perpendicular-type energy transfer. 相似文献
83.
We developed a compact three-stage Ti:sapphire amplifier laser system that produced peak power in excess of 100 TW for a pulse duration of less than 19 fs and an average power of 19 W at a 10-Hz repetition rate. A final 40-mm-diameter Ti:sapphire amplifier is pumped by a Nd:YAG master-oscillator-power-amplifier system that produces ~7-J output of 532-nm radiation. The spatial beam quality is approximately 2 times diffraction limited for the full amplified compressed output pulse. With f/3 optics, this system should therefore be capable of producing a focused intensity of ~3x10(20) W/cm(2) . 相似文献
84.
Takuma Tahara Dr. Shuichi Suzuki Prof. Dr. Masatoshi Kozaki Prof. Dr. Daisuke Shiomi Dr. Kenji Sugisaki Prof. Dr. Kazunobu Sato Prof. Dr. Takeji Takui Yota Miyake Prof. Dr. Yuko Hosokoshi Prof. Dr. Hiroyuki Nojiri Prof. Dr. Keiji Okada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7201-7209
The spin–spin and magnetic properties of two (nitronyl nitroxide)-(di-p-anisylamine-phenothiazine) diradical cation salts, ( DAA-PTZ ) + -NN⋅ MBr4− (M=Ga, Fe), have been investigated. These diradical-cation species were prepared by the cross-coupling of iodophenothiazine DAA-PTZ-I with NN-AuPPh3 followed by oxidation with the thianthrenium radical cation ( TA+⋅ MBr4−). These salts were found to be highly stable under aerobic conditions. For the GaBr4 salt, large ferromagnetic intramolecular and small antiferromagnetic intermolecular interactions (J1/kB=+320 K and J2/kB=−2 K, respectively) were observed. The magnetic property of the Fe3+ salt was analyzed by using a six-spin model assuming identical intramolecular exchange interaction (J3/kB=+320 K) and the other exchange interactions (J4/kB=−7 K and J5/kB=−4 K). A significant color change was observed in the UV/Vis/NIR absorption spectra upon electrochemical oxidation of the doublet DAA-PTZ-NN to the triplet ( DAA-PTZ ) + -NN . 相似文献
85.
Koseki T Onishi H Takahashi Y Uchida M Machida Y 《Chemical & pharmaceutical bulletin》2008,56(10):1384-1388
It was attempted to produce novel furosemide (FS) fast-disintegrating tablets by direct compression. The combination of FS, microcrystalline cellulose, croscarmellose sodium and xylitol was used as the basic formulation, and sucrose stearic acid ester (SSE) was chosen as an additional additive. The tablets with SSE were prepared by the simple addition of SSE, using a lyophilized mixture of FS and SSE or using a FS/SSE mixture obtained by evaporation of their ethanol solution. Only the tablets, produced using the FS/SSE mixture obtained by organic solvent (ethanol) evaporation, showed hardness of more than 30 N and a disintegration time of less than 20 s, which were the properties suitable for fast-disintegrating tablets. These properties were considered to result from well-mixed and fine-powdered SSE and FS. 相似文献
86.
Dr. Chihiro Maeda Keiji Nagahata Takuma Shirakawa Prof. Tadashi Ema 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7887-7891
Helical carbazole-based BODIPY analogues were readily synthesized via aza[7]helicenes. The structures of azahelicene-incorporated BF2 dyes were elucidated by x-ray diffraction analysis. DFT calculations revealed that the π-conjugated system expanded from the helicene moiety to the BODIPY framework. The azahelicene-fused boron complexes showed the Cotton effects and the circularly polarized luminescence (CPL) in the visible region. Furthermore, an axially chiral binaphthyl group was attached to the helically chiral dyes, which enhanced the chiroptical properties. 相似文献
87.
The cycloisomerization of 1,4-enyne 1 in the presence of platinum(II) catalyst afforded 1,2,3-trisubstituted 1H-indene 2 and 2' in good to excellent yields. The reaction proceeded through an unprecedented 1,2-alkenyl rearrangement that afforded a novel reaction topology of 1,4-enynes. 相似文献
88.
Takuma KobayashiShuichi Matsumura 《Polymer Degradation and Stability》2011,96(12):2071-2079
Novel biodegradable and biobased thermoplastic elastomers, poly[dodecanolide-12-hydroxystearate (12HS)], poly(pentadecanolide-12HS) and poly(hexadecanolide-12HS) with Mws of 140,000-290,000 g mol−1 were prepared by the enzymatic copolymerization of a macrolide as the hard segment and methyl 12HS as the soft segment. Their thermal properties, such as Tm and Tc, were measured by DSC. Physicochemical and mechanical properties, such as crystallinity, were also measured. The polymer structures were analyzed with respect to the sequence of the two monomers by 1H NMR spectroscopy using an europium shift reagent. The randomness of the two monomer units in the polymer chain increased with the polymerization time. Both Young’s modulus and tensile strength decreased with increasing 12HS content in the copolymer. In contrast, elongation at break increased with increasing 12HS content, thus demonstrating the copolymers’ elastomeric properties. These copolymers showed biodegradabilities by activated sludge, which also increased with increasing 12HS content. 相似文献
89.
Torigoe H Rahman SM Takuma H Sato N Imanishi T Obika S Sasaki K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(9):2742-2751
Due to the instability of pyrimidine motif triplex DNA at physiological pH, triplex stabilization at physiological pH is crucial in improving its potential in various triplex-formation-based strategies in vivo, such as gene expression regulation, genomic DNA mapping, and gene-targeted mutagenesis. To this end, we investigated the thermodynamic and kinetic effects of our previously reported chemical modification, 2'-O,4'-C-aminomethylene-bridged nucleic acid (2',4'-BNA(NC)) modification of triplex-forming oligonucleotide (TFO), on triplex formation at physiological pH. The thermodynamic analyses indicated that the 2',4'-BNA(NC) modification of TFO increased the binding constant of the triplex formation at physiological pH by more than 10-fold. The number and position of the 2',4'-BNA(NC) modification in TFO did not significantly affect the magnitude of the increase in the binding constant. The consideration of the observed thermodynamic parameters suggested that the increased rigidity and the increased degree of hydration of the 2',4'-BNA(NC)-modified TFO in the free state relative to the unmodified TFO may enable the significant increase in the binding constant. Kinetic data demonstrated that the observed increase in the binding constant by the 2',4'-BNA(NC) modification resulted mainly from the considerable decrease in the dissociation rate constant. The TFO stability in human serum showed that the 2',4'-BNA(NC) modification significantly increased the nuclease resistance of TFO. Our results support the idea that the 2',4'-BNA(NC) modification of TFO could be a key chemical modification to achieve higher binding affinity and higher nuclease resistance in the triplex formation under physiological conditions, and may lead to progress in various triplex-formation-based strategies in vivo. 相似文献
90.
Efficient luminescence from a copper(I) complex doped in organic light-emitting diodes by suppressing C-H vibrational quenching 总被引:1,自引:0,他引:1
Wada A Zhang Q Yasuda T Takasu I Enomoto S Adachi C 《Chemical communications (Cambridge, England)》2012,48(43):5340-5342
Efficient luminescence was realized by suppressing not only excited-state distortion but also C-H vibrational quenching in a Cu complex. Organic light-emitting diodes containing the Cu complex as an emitting dopant exhibited a maximum external quantum efficiency of 7.4%. 相似文献