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61.
Megumi Kayanuma Narayan Bera Martina Sandroni Yann Pellegrin Errol Blart Fabrice Odobel Chantal Daniel 《Comptes Rendus Chimie》2012,15(2-3):255-266
The structures and electronic absorption spectra of newly synthesized heteroleptic copper (I) complexes [CuL1L2]+ (L1 = phen-imidazole and/or L2 = dipyrido [3,2-a:2’,3’-c] phenazine derivatives) are analyzed under the light of density functional theory (DFT) and time-dependent DFT (TD-DFT). The ground states geometries, characterized by π-stacking interactions, have been optimized using PBE-D functional taking into account dispersion correction. The UV-visible theoretical absorption spectra have been calculated using B3LYP functional in vacuum and taking into account solvent corrections by means of the polarized continuum model (PCM). Whereas the PBE-D functional is well adapted to the determination of the structures, it does underestimate drastically the transition energies. The spectra are characterized by high density of states, mainly metal-to-ligand-charge-transfer (MLCT) and intra-ligand (IL), between 600 nm and 250 nm. Most of the complexes show an intense band in the near-UV energy domain (~320 nm) corresponding to an IL transition. The lowest part of the absorption spectra, starting at 600 nm, corresponds to MLCT transitions leading to a shoulder observed experimentally between 400 and 500 nm. The upper part of the spectra, beyond 300 nm, puts in evidence strong mixing between ligand-to-ligand-charge-transfer (LLCT), IL and MLCT states. 相似文献
62.
Rates of crystal nucleation in alkali disilicate glasses were measured by counting the number of crystals under an optical microscope. The viscosities of these glasses were measured by the method of beam-bending and penetration. Using the data of rate of nucleation and viscosity obtained in the present study and the data of free energy measured by Takahashi and Yoshio, crystal-glass interfacial energies for alkali disilicate systems were estimated on the basis of homogeneous nucleation theory as follows: 196 erg/cm2 for Li2O·2SiO2, 126–144 erg/cm2 for Na2O·2SiO2 and 88–104 erg/cm2 for K2O·2SiO2. The effects of the viscosity of glass, the free energy difference between crystal and glass and crystal-glass interfacial energy on the rate of nucleation were discussed, and the remarkably higher rate of crystal nucleation in the Li2O·2SiO2 glass was attributed to the larger free energy difference. 相似文献
63.
Koichi Machida Megumi Yamauchi Eriko Kurashina Masao Kikuchi 《Helvetica chimica acta》2010,93(11):2164-2175
Four new tetrahydrofuranoid lignan glycosides, (7S,8R,7′R,8′S)‐4,9,4′,7′‐tetrahydroxy‐3,3′‐dimethoxy‐7,9′‐epoxylignan 9‐O‐β‐D ‐glucopyranoside ( 2 ), (7R,8S,7′S,8′R)‐4,9,4′,7′‐tetrahydroxy‐3,3′‐dimethoxy‐7,9′‐epoxylignan 9‐O‐β‐D ‐glucopyranoside ( 3 ), (7R,8S,7′R,8′S)‐4,9,4′,9′‐tetrahydroxy‐3,3′‐dimethoxy‐7,7′‐epoxylignan 9‐O‐β‐D ‐glucopyranoside ( 4 ), and rel‐(7R,8S,7′S,8′R)‐4,9,4′,9′‐tetrahydroxy‐3,3′‐dimethoxy‐7,7′‐epoxylignan 9‐O‐β‐D ‐glucopyranoside ( 5 ), and ten known lignan glycosides, 1 and 6 – 14 , were isolated from the leaves of Osmanthus fragrans Lour. var. aurantiacus Makino . Their structures were established on the basis of spectral and chemical studies. 相似文献
64.
Kenichi Murata Kazuki Kajiya Megumi Nukaga Yosuke Suga Toshiyuki Watanabe Nobuhumi Nakamura Hiroyuki Ohno 《Electroanalysis》2010,22(2):185-190
A simple method for constructing gold nanoparticle‐modified electrodes with three‐dimensional nanostructures is demonstrated. The electrodes were prepared by casting citrate‐reduced AuNPs onto polycrystalline gold electrodes. The resultant electrodes had a large surface area‐to‐volume ratio, adequate for high protein loading and conferring high stability. The gold nanoparticle electrodes were covered with a self‐assembled monolayer of 11‐mercaptoundecanoic acid for electrostatic immobilization of cytochrome c (cyt c). At the electrode, direct, reversible electron transfer from cyt c was observed with remarkable stability. Moreover, an extremely high surface coverage of electrochemically active cyt c, 167 fully packed monolayers, was obtained through use of the electrode. 相似文献
65.
Megumi Akiyama 《Tetrahedron letters》2006,47(14):2287-2290
The absolute stereochemistry of plakortone E, a cytotoxic metabolite of the Caribbean sponge, was established to be 1, by the synthesis of the racemic C-8 epimer (±)-2 and then of (−)-1 itself, which was identical with the natural compound. 相似文献
66.
A newly designed axially chiral guanidine is found to function as an effective platform for asymmetric induction at the alpha-carbon of unsymmetrically substituted 1,3-dicarbonyl compounds. Highly efficient and enantioselective electrophilic amination of various 1,3-dicarbonyl compounds with azodicarboxylate was successfully achieved using the present chiral guanidine catalyst, which provides efficient access to the construction of nitrogen-substituted quaternary stereocenters in an optically active form. 相似文献
67.
Nagaokaa MH Nagaoka H Kondo K Akiyama H Maitani T 《Chemical & pharmaceutical bulletin》2006,54(6):922-924
Agaricus blazei MURRILL mushroom products are sold as so-called health foods in Japan. However, a part of Agaricus is known to contain hydrazines. A sensitive and specific method for analyzing a genotoxic hydrazine, agaritine, and its derivatives was developed to assess the safety of Agaricus products. beta-N-(gamma-L(+)-Glutamyl)-4-(hydroxymethyl)phenylhydrazine (agaritine, AGT), 4-hydrazinylbenzylalcohol (HMPH), 4-hydrazinylbenzoic acid (CPH), 4-methylphenylhydrazine (MPH) and phenylhydrazine (PH) were converted to their correspond-ing fluorescent derivatives with 3,4-dihydro-6,7 dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride (DMEQ-COCl) as the fluorescence derivatization reagent. The detection limits (S/N=3) for CPH, AGT, PH and MPH were 422, 45.3, 16.5 and 138 fmol, respectively, in a 20 mul injection volume. Recoveries, achieved by adding known AGT amounts to the Agaricus sample and Agaricus products, ranged from 92.8 to 102%. By using this method which does not require partial purification of the Agaricus sample, the amounts of AGT in several types of foods were found to be 112-1836 mug/g dry weight. 相似文献
68.
Shigeto Fukushima Megumi Machida Tomoko Akutsu Kazuhisa Shimizu Shigeo Tanaka Kazuya Okamoto Hiroko Mashiba Masayuki Yokoyama Teruo Okano Yasuhisa Sakurai Kazunori Kataoka 《Colloids and surfaces. B, Biointerfaces》1999,16(1-4):227-236
Adriamycin (ADR) dimer was prepared and its antitumor activity was evaluated with mouse colon adenocarcinoma 26 (C 26). As compared with original ADR, the dimer did not show significant antitumor activity, either in vitro or in vivo. Furthermore, polymeric micelles containing varied ratios of the dimer to the original ADR were prepared. Polymeric micelles with a higher dimer/ADR ratio (9.7) showed significant antitumor activity, but the effective dose shifted higher. Effective doses were found to largely depend on the concentration of the original ADR, rather than that of the dimer at the tumor sites. Therefore, it was presumed that the original ADR played a major role in antitumor activity, and the dimer played a supplementary role to contribute selective delivery of ADR to the tumor sites. 相似文献
69.
Yamada S Wang D Li S Nishikawa M Qian EW Ishihara A Kabe T 《Chemical communications (Cambridge, England)》2003,(7):842-843
A sulfur exchange reaction between di-tert-butylpolysulfides and elemental sulfur was examined using a 35S tracer method and the reaction mechanism was discussed. 相似文献
70.
Vanadium (V) is an essential metal for mammals. It has different valence states. In blood, V is bound to transferrin (Tf), a glycoprotein that has two metal-binding sites (C-lobe site and N-lobe site). In the present study, the binding patterns of V to serum Tf were analyzed by combined on-line HPLC and high-resolution ICP-MS (HPLC/HR-ICP-MS). The levels of (51)V, (56)Fe and (32)S, which are interfered with polyatomic ions such as (35)Cl(16)O(+), (38)Ar(13)C(+) and (37)Cl(14)N(+), (40)Ar(16)O(+) and (40)Ca(16)O(+), and (16)O(2)(+), respectively, when using quadrupole ICP-MS, could be monitored simultaneously by HR-ICP-MS at a resolution of m/[capital Delta]m= 4000. Sample (a 1 ml portion of serum from a healthy person or 2 mg of human serum Tf (hTf)) was directly subjected to HPLC equipped with an anion-exchange column. V in human serum without any in vitro V spike was detected as V(C)-Tf (V bound to C-lobe site of Tf) and metal(2)-Tf. Since V(iii) was most favorable in terms of the binding to hTf in the presence of bicarbonate and V bound to the C-lobe site of hTf was detected only in the case of V(iii) among the three valence states of V, it was suggested that a part, at least, of V in the V(C)-Tf in healthy human serum may be present as V(iii), in addition to the generally accepted V(iv). 相似文献