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排序方式: 共有930条查询结果,搜索用时 31 毫秒
91.
Yuki Nagao Yuzuru Imai Jun Matsui Tomoyuki Ogawa Tokuji Miyashita 《The Journal of chemical thermodynamics》2011,43(4):613-616
We synthesized seven partially protonated poly(aspartic acids)/sodium polyaspartates (P-Asp) with different average molecular weights to study their proton transport properties. The number-average degree of polymerization (DP) for each P-Asp was 30 (P-Asp30), 115 (P-Asp115), 140 (P-Asp140), 160 (P-Asp160), 185 (P-Asp185), 205 (P-Asp205), and 250 (P-Asp250). The proton conductivity depended on the number-average DP. The maximum and minimum proton conductivities under a relative humidity of 70% and 298 K were 1.7 · 10?3 S cm?1 (P-Asp140) and 4.6 · 10?4 S cm?1 (P-Asp250), respectively. Differential thermogravimetric analysis (TG-DTA) was carried out for each P-Asp. The results were classified into two categories. One exhibited two endothermic peaks between t = (270 and 300) °C, the other exhibited only one peak. The P-Asp group with two endothermic peaks exhibited high proton conductivity. The high proton conductivity is related to the stability of the polymer. The number-average molecular weight also contributed to the stability of the polymer. 相似文献
92.
The peroxidase activity of horse cytochrome c was enhanced by its dimerization, where its Compound III (oxy-form) and Compound I (oxoferryl porphyrin π-cation radical) species were detected in the reactions with hydrogen peroxide and meta-chloroperbenzoic acid, respectively. These results show that oligomeric cytochrome c can contribute as a proapoptotic conformer by the increased peroxidase activity. 相似文献
93.
Thermal [2+2] cycloaddition of morpholinoenamines with C60 via a single electron transfer 总被引:1,自引:0,他引:1
The thermal reaction of C(60) with five- and six-membered morpholinocycloalkenes in refluxing toluene exclusively gave the [2+2] cycloadducts in high yields. However, a seven-membered homologue sluggishly reacted with C(60) because of the increasing steric hindrance. This cycloaddition reaction is likely to proceed via a single electron transfer (SET), a radical-coupling, and subsequent ion cyclization rather than the prior proton transfer between the radical ions. 相似文献
94.
Sano S Okubo Y Handa A Nakao M Kitaike S Nagao Y Kakegawa H 《Chemical & pharmaceutical bulletin》2011,59(7):885-888
Isoliquiritigenin [ILG, (E)-1] was readily prepared via the Horner-Wadsworth-Emmons reactions using β-ketophosphonates 5a, b. An improved protocol for the synthesis of (E)-1 via the Claisen-Schmidt condensation was also presented. 相似文献
95.
Itoh A Saitoh T Tani K Uchigaki M Sugimoto Y Yamada J Nakajima H Ohshiro H Sun S Tanahashi T 《Chemical & pharmaceutical bulletin》2011,59(8):947-951
From the embryos of the seeds of Nelumbo nucifera, three bisbenzylisoquinoline alkaloids, nelumboferine and nelumborines A and B, were isolated along with four known compounds, neferine, liensinine, isoliensinine and anisic acid. The structures of the new alkaloids were determined mainly by spectroscopic methods. 相似文献
96.
The formation of a cocrystallized coordination compound, [Pd(3)(D-pen)(3)](2)·[M(en)(3)](ClO(4))(3) (D-H(2)pen = D-penicillamine; M = Co(III) or Rh(III)), from [Pd(3)(D-pen)(3)] and [M(en)(3)](ClO(4))(3) is reported. In this compound, only the Δ-configurational [M(en)(3)](3+) cations were incorporated when its racemic (Δ/Λ) isomer was employed. Besides this enantioselective incorporation of complex cations, this compound was found to show the selective incorporation of ClO(4)(-) as the anion species. 相似文献
97.
Aromatic dicarbonitrile bearing cyano groups in a 1,4-relationship was utilized for a phthalocyanine synthesis to give azepiphthalocyanine having a seven-membered ring unit instead of a five-membered ring unit. This molecule exhibits a significantly twisted structure and large splitting of the Q band absorption, indicative of its azachlorin-like conjugation system. 相似文献
98.
Kikukawa Y Fukuda T Fuyuhiro A Ishikawa N Kobayashi N 《Chemical communications (Cambridge, England)》2011,47(30):8518-8520
Soluble copper phthalocyanine (CuPc) and naphthalocyanine (CuNc) precursors which can be converted thermally and photochemically into insoluble CuPc and CuNc, respectively, have been synthesized by a one-step reaction using commercially available chemicals. 相似文献
99.
Naomi Warashina Masahiro Tsuchiya Kaori Ishimaru Takakazu Kojima 《Journal of Thermal Analysis and Calorimetry》2011,105(2):473-477
Imbalance condensation of diaminophenylbenzimidazole, DAPBI, with terephthaloyl chloride, TPC was conducted for the purpose
of synthesis of macromonomers, expected to be used in syntheses of aromatic polyamides with structural regularities. The products
are soluble in dimethylsulfoxide—d6, and their 1H NMR spectra indicate that all the products are carboxyl-terminated. The
signal of carboxyphenyl linked to chain ends is different from that of terephthaloyl in the 1H NMR spectra. By use of the
ratio of the signal intensity of the former to that of the latter, the number-average degree of polymerization, DP
NMR is determined. With the mole ratio in feed, DP
NMR of the product increases. The TG thermograms of the products are a multistage one. Each stage is classified by temperature
and mass loss at an inflection point. Mass loss of each stage classified by temperature at an inflection point corresponds
to mass fraction of an aromatic amide with a characteristic degree of polymerization, DP, and that is, the DP distribution of the products is roughly estimated from the TG thermograms. The DP distribution of macromonomers influences performance of aromatic polyamides with structural regularities, derived from the
macromonomers. The convenient estimation method of DP distribution by TG is useful in industries of high-performance polymers. To the knowledge, such convenient technique has
never reported. 相似文献
100.
Fukushima M Mizutani Y Maeno S Zhu Q Kuramitz H Nagao S 《Molecules (Basel, Switzerland)》2011,17(1):48-60
The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs) by iron(III)-porphyrin/KHSO? catalytic systems was investigated. Iron(III)-5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (FeTHP) and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyde poly-condensation. F (TrFP), Cl (TrCP), Br (TrBP) and I (TrIP) were examined as halogen substituents for TrXPs. Although the supported catalysts significantly enhanced the degradation and dehalogenation of TrFP and TrCP, the oxidation of TrBP and TrIP was not enhanced, compared to the FeTHP catalytic system. These results indicate that the degree of oxidation of TrXPs is strongly dependent on the types of halogen substituent. The order of dehalogenation levels for halogen substituents in TrXPs was F > Cl > Br > I, consistent with their order of electronegativity. The electronegativity of a halogen substituent affects the nucleophilicity of the carbon to which it is attached. The levels of oxidation products in the reaction mixtures were analyzed by GC/MS after extraction with n-hexane. The most abundant dimer product from TrFP via 2,6-difluoroquinone is consistent with a scenario where TrXP, with a more electronegative halogen substituent, is readily oxidized, while less electronegative halogen substituents are oxidized less readily by iron(III)-porphyrin/KHSO? catalytic systems. 相似文献