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Porphyrin Arch-Tapes: Synthesis, Contorted Structures, and Full Conjugation
Fukui, Norihito,Kim, Taeyeon,Kim, Dongho,Osuka, Atsuhiro American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.26
<P>Porphyrin tapes possessing meso-meso beta-beta beta-beta triple direct linkages have been targets of extensive studies because of their fully conjugated characteristic pi-electronic networks. In this paper, we report porphyrin arch tapes that bear additional carbonyl group(s) or methylene group(s) inserted between one of the beta-beta linkage(s) of the porphyrin tapes. The carbonyl-inserted porphyrin arch-tapes were efficiently synthesized by double fusion reactions of beta-to-beta carbonyl-bridged porphyrin oligomers with DDQ and Sc(OTf)(3), and were converted to the methylene-bridged porphyrin arch-tapes via Luche reduction with NaBH4 and CeCl3 followed by ionic hydrogenation with HBF4 center dot OEt2 and BH3 center dot NEt3. While the conventional porphyrin tapes display rigid and planar structures and low solubilities, these porphyrin arch-tapes show remarkably contorted structures, flexible conformations, and improved solubilities because of the presence of the incorporated seven-membered ring(s). Interestingly, the methylene inserted arch-tapes exhibited conjugative electronic interactions that were comparable to those of porphyrin tapes probably owing to through-space interaction in the contorted conformations. The carbonyl-inserted arch-tapes displayed distinctly larger conjugative interactions owing to an active involvement of the carbonyl group(s) in the electronic conjugation. A similar trend was observed in the nonlinear optical properties, as evidenced by their two-photon absorption cross sections. Furthermore, as a benefit of the contorted structures, these porphyrin arch-tapes can catch C-60 fullerene effectively. Naturally, the electron-rich methylene-bridged arch-tapes exhibited larger association constants than the electron-deficient carbonyl-bridged arch-tapes. Among these arch-tapes, a methylene-bridged syn-Ni(II) porphyrin trimer recorded the largest association constant of (1.5 +/- 0.4) X 10(7) M-1 in toluene at 25 degrees C.</P>
Fukui, Norihito,Lee, Seung-Kyu,Kato, Kenichi,Shimizu, Daiki,Tanaka, Takayuki,Lee, Sangsu,Yorimitsu, Hideki,Kim, Dongho,Osuka, Atsuhiro Royal Society of Chemistry 2016 Chemical science Vol.7 No.7
<▼1><P>Oxidation of 10,15,20-triaryl Ni(<SMALL>II</SMALL>)-porphyrins bearing an electron-withdrawing substituent at the 5-position with DDQ and FeCl<SUB>3</SUB> gave 10,12- and 18,20-doubly phenylene-fused Ni(<SMALL>II</SMALL>)-porphyrins regioselectively.</P></▼1><▼2><P>Oxidation of 10,15,20-triaryl Ni(<SMALL>II</SMALL>)-porphyrins bearing an electron-withdrawing substituent at the 5-position with DDQ and FeCl<SUB>3</SUB> gave 10,12- and 18,20-doubly phenylene-fused Ni(<SMALL>II</SMALL>)-porphyrins regioselectively. A doubly phenylene-fused <I>meso</I>-chloro porphyrin thus prepared was reductively coupled to give a <I>meso</I>–<I>meso</I> linked dimer, which was further converted to a quadruply phenylene-fused <I>meso</I>–<I>meso</I>, β–β, β–β triply linked Zn(<SMALL>II</SMALL>)–diporphyrin <I>via</I> inner-metal exchange followed by oxidation with DDQ and Sc(OTf)<SUB>3</SUB>. As compared to the usual <I>meso</I>–<I>meso</I>, β–β, β–β triply linked Zn(<SMALL>II</SMALL>)-diporphyrin, this π-extended porphyrin dyad exhibits a smaller HOMO–LUMO gap and a larger two-photon absorption cross-section.</P></▼2>
Loss Analysis of Hybrid Electric Vehicle Inverters
Fumio Asakura,Norihito Kimura,Yuji Hayashi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The analysis of electrical losses of hybrid electric vehicle (HEV) inverters is significant for improved fuel efficiency for HEVs. To analyze the breakdown of electrical losses in LA-4 Cycle or under other similar driving conditions, measurement and calculation methods have been developed to ascertain losses attributable to different parts of HEV inverters. To determine electrical losses, the methods use voltages and currents in HEV inverters measured with a vehicle-mounted virtual and real simulator (VRS)
Hydrothermal (K1−xNax)NbO3 Lead-free Piezoelectric Ceramics
Takafumi Maeda,Norihito Takiguchi,Takeshi Morita,Mutsuo Ishikawa,Tobias Hemsel 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.41
As a lead-free piezoelectric ceramic, (K,Na)NbO3 is a promising material because of its good piezoelectric properties. In this study, (K1−xNax)NbO3 ceramics were synthesized from a mixture of KNbO3 and NaNbO3 powders prepared by using the hydrothermal reaction. The hydrothermal reaction enables the production of high quality powders for the ceramic fabrication process. To obtain (K1−xNax)NbO3 ceramics, the KNbO3 and the NaNbO3 powders were mixed and sintered together. X-Ray diffraction analysis revealed that the solid solution ceramic (K1−xNax)NbO3 was formed by the sintering process. The K/Na ratio in the (K1−xNax)NbO3 ceramic was optimized for the best piezoelectric properties. The optimized form was (K0.48Na0.52)NbO3, which showed the following piezoelectric properties: k33 = 0.56 and d33 = 114 pC/N. In addition, the ferroelectric properties Pr = 7.72 μC/cm2, Ec = 857 V/mm, and Tc = 420 ℃ were measured.