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991.
Hiroki Kamiya Takeshi Kondo Takafumi Sakida Dr. Shigeru Yamaguchi Prof. Dr. Hiroshi Shinokubo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(50):16129-16135
Facile synthesis of meso‐aryl‐substituted 5,15‐dithiaporphyrins and 10‐thiacorroles has been achieved by sulfidation of α,α′‐dichlorodipyrrin metal complexes with sodium sulfide in DMF. Thiacorrole metal complexes exhibit distinct aromaticity due to 18 π‐conjugation including the lone pair on sulfur, whereas dithiaporphyrins are nonaromatic judging from 1H NMR spectra, X‐ray analysis, and absorption spectra. We have found that NiII and AlIII dithiaporphyrin complexes undergo smooth thermal sulfur extrusion reaction to give the corresponding thiacorrole complexes, whereas free base, ZnII, PdII, and PtII dithiaporphyrin complexes did not exhibit the similar reactivity. The DFT calculations have elucidated a reaction pathway involving an episulfide intermediate, which can explain the markedly different reactivity among dithiaporphyrin metal complexes. 相似文献
992.
We propose a new omnibus test statistic for normality based on the Jarque–Bera test statistic. We give the exact first four
moments of the null distribution for the statistic using a computer algebra system. Our proposed statistic is an improvement
of Jarque–Bera test statistic. Then the cumulants of the standardized statistic satisfy the Cornish–Fisher assumption. We
give a normalizing transformation of the statistic based on the Wilson–Hilferty transformation. 相似文献
993.
994.
Qun Xu Chun Xu Yanping Wang Wen Zhang Litong Jin Kazuhiko Tanaka Hiroki Haraguchi Akihide Itoh 《Analytical and bioanalytical chemistry》2000,368(8):791-796
An amperometric detector with two working electrodes both modified with polydiphenylamine-dodecyl sulfate (PDPA-DS) was successfully used for the simultaneous determination of electroinactive anions (SO4 2–, Cl–, NO3 –) and cations (Na+, NH4 + and K+) in single-column ion-exclusion cation-exchange chromatography (IEC-CEC). The PDPA-DS chemical modified electrode (CME) was based on the incorporation of dodecyl sulfate (DS) into PDPA by electropolymerization of diphenylamine in the presence of sodium dodecyl sulfate. The electrochemical responses against the anions and cations at the PDPA-DS CME in differential pulse voltammetry were studied. A set of well-defined peaks of electroinactive anions and cations were obtained. The anions and cations were detected conveniently and reproducibly in a linear concentration range 0.01–5.0 mmol/L and their detection limits were in the range 5–9 μmol/L at a signal-to-noise ratio of 3 (S/N = 3). The proposed method was quick, sensitive and simple and was successfully applied to the analysis of lake water samples. The working electrode was stable over one week period of operation with no evidence of chemical and mechanical deterioration. 相似文献
995.
Hiroki Asao Yoko Nakamura Yukito Furuya Shigefumi Kuwahara Bill J. Baker Hiromasa Kiyota 《Helvetica chimica acta》2010,93(10):1933-1944
Four stereoisomers of (+)‐pteroenone, a defensive metabolite of the abducted Antarctic pteropod Clione antarctica, were synthesized by employing anti‐/syn‐selective aldol reactions as the key step. These compounds displayed no antifeedant activity against a generally benthic Antarctic fish that does not co‐occur with this pteropod. 相似文献
996.
Ryosuke Takeda Akie Kawamura Aki Kawashima Dr. Tatsunori Sato Dr. Hiroki Moriwaki Dr. Kunisuke Izawa Prof. Dr. Kenichi Akaji Shuni Wang Prof. Dr. Hong Liu Dr. José Luis Aceña Prof. Dr. Vadim A. Soloshonok 《Angewandte Chemie (International ed. in English)》2014,53(45):12214-12217
Reported herein is the first purely chemical method for the dynamic kinetic resolution (DKR) of unprotected racemic α‐amino acids (α‐AAs), a method which can rival the economic efficiency of the enzymatic reactions. The DKR reaction principle can be readily applied for S/R interconversions of α‐AAs, the methodological versatility of which is unmatched by biocatalytic approaches. The presented process features a virtually complete stereochemical outcome, fully recyclable source of chirality, and operationally simple and convenient reaction conditions, thus allowing its ready scalability. A quite unique and novel mode of the thermodynamic control over the stereochemical outcome, including an exciting interplay between axial, helical, and central elements of chirality is proposed. 相似文献
997.
Inoue Y Miyauchi M Nakajima H Takashima Y Yamaguchi H Harada A 《Journal of the American Chemical Society》2006,128(28):8994-8995
Poly(ethylene glycol) (PEG)-substituted cyclodextrins (CDs) with different chain lengths have been synthesized. PEG-substituted CDs formed self-threading complexes in aqueous solutions, and the conformational exchange dynamics between self-threading and dethreading could be regulated by its chain length. 相似文献
998.
Mizuno T Nemoto T Tansho M Shimizu T Ishii H Takegoshi K 《Journal of the American Chemical Society》2006,128(30):9683-9686
(2)H NMR was examined as an approach to determine (1)H chemical shifts in solids. For high-resolution observation, the line width due to (2)H quadrupole interaction and chemical-shift anisotropy was removed by magic-angle spinning and that due to (1)H-(2)H dipolar interactions by (1)H decoupling. Further, we showed that the sensitivity can be enhanced by applying (1)H to (2)H cross polarization and by adding spinning-sideband spectra. These make it possible to obtain (2)H natural-abundance MAS spectra revealing highly resolved (2)H signals. The second-order quadrupole effects of (2)H are also examined. 相似文献
999.
Hifumi H Yamaoka S Tanimoto A Citterio D Suzuki K 《Journal of the American Chemical Society》2006,128(47):15090-15091
A new nanoparticulate inorganic-organic hybrid-type positive contrast agent (CA), PGP/dextran-K01, was synthesized based on a GdPO4 inorganic core as a relaxation-time-shortening moiety and a dextran-coating, which generates monodispersibility in water, a high relaxation-time-shortening effect by retaining a large number of water molecules in proximity of the core and toxicity reduction in in-vivo studies. This PGP/dextran-K01 nanoparticle has high r1 and r2 values and a significantly low r2/r1 value, 1.1, which is unprecedented and which is the lowest value among existing nanoparticulate CAs indicating that PGP/dextran-K01 is a positive contrast agent. Because of this low r2/r1 value and the nanoparticulate shape, PGP/dextran-K01 will be a useful clinical substitute for negative CAs based on iron oxides. 相似文献
1000.
Shirai A Sumitomo T Yoshida M Kaimura T Nagamune H Maeda T Kourai H 《Chemical & pharmaceutical bulletin》2006,54(5):639-645
We synthesized gemini quaternary ammonium compounds (gemini QACs) having two thiazolium moieties in a molecule, 5,5'-[2,2'-(alpha,omega-polymethylnedicarbonyldioxy)diethyl]bis(3-alkyl-4-methylthiazolium iodide) (5DEBT-m,n), on which the carbon number of the methylene chain linking the two thiazoles (m) is 2, 6 or 8 and that of the alkyl group (n) is 8, 10, 12, 14 or 16. 5,5'-[2,2'-(p-Phenylenedicarbonyldioxy)diethyl]bis(3-alkyl-4-methylthiazolium bromide) (5DEBT-P,n) was then synthesized, which is composed of a p-phenylene as the methylene spacer. For five gemini QAC series, in addition to the previously described 5DEBT-4,n to the four new compound series, their antimicrobial activities were determined. 5DEBT-m,10 and -P,10 exhibited a wide and strong bacteriostatic activity against gram-negative and -positive bacteria, fungi and then yeast in comparison with N-tetradecyl-5-(2-hydroxyethyl)-4-methylthiazolium iodide as a mono-QAC. The bactericidal activity of the 5DEBT series against Escherichia coli IFO 12713 and Staphylococcus aureus IFO 12732 was investigated on the basis of the effects of their alkyl chain length and their molecular hydrophobicity. It was found that the effect of theses factors on their activity significantly changes by the difference between the gram-negative and -positive bacteria. Although against the gram-negative bacterium, the change in the activity due to extension of the alkyl group for each compound affected the kind of methylene spacer, against the gram-positive bacterium, it was almost equal in spite of the methylene spacer. This result could be responsible for the bactericidal mechanism of the gemini QACs being influenced by the diversity of the steric structure participating in the methylene chain length and by the bacterium cell surface hydrophobicity. 相似文献