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51.
Koichi Fukase Hideo Nakayama Motohiro Kurosawa Toshiki Ikegaki Takeshi Kanoh Sumihiro Hase 《Journal of carbohydrate chemistry》2013,32(5):715-736
Abstract New bifunctional reagents, 2-amino-6-carboxyethylpyridine and 2-amino-6-cyanoethylpyridine, were designed and synthesized in order to provide a novel procedure for preparation of neoglycoconjugates from fluorescence-labeled and purified sugar chains. Labeling of model sugar chains with these reagents was effected by reductive amination using BH3.Me2NH to give corresponding 6-carboxyethylpyridylaminated (CEPA-) and 6-cyanoethylpyridylaminated (CNEPA-) derivatives, which were readily purified by reversed phase HPLC. The reagent parts of the labeled products possess the functional groups which then serve as linkers for coupling with matrices such as proteins and polymers. A CEPA-derivative of glucose was directly coupled with the ε-amino group of a Lys derivative to give a neoglycoprotein model. CNEPA-sugars were hydrogenated to give 6-aminopropylpyridylaminated (APPA-) derivatives, which can then be readily used for the preparation of various types of neoglycoconjugates by use of appropriate spacers as exemplified by the coupling of APPA-maltotriose with bovine serum albumin (BSA), biotin, and acrylic acid. The reaction of APPA-maltotriose with succinimidyl 3-(3-nitro-2-pyridyldithio)propionate gave the corresponding amide to be used for a disulfide formation with BSA. Condensation with biotin was effected by use of N-hydroxysuccinimidobiotin. The conjugation of APPA-maltotriose with acrylic acid was carried out by use of 4-acryloyloxyphenyldimethylsulfonium methylsulfate to give the corresponding acrylamide, which can be used for the preparation of sugar-acrylamide copolymers. 相似文献
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53.
Shigeru Sasaki 《Journal of organometallic chemistry》2011,696(21):3307-3315
The sterically crowded triarylphosphines bearing formyl and benzoyl groups were synthesized and characterized by X-ray crystallography. The benzoyl derivative was converted to the p-quinomethane conjugated with the triarylphosphine. The McMurry coupling of the formyl derivative afforded the diarylethene bearing the two sterically-crowded-triarylphosphine moieties. The cyclic voltammograms of these compounds show reversible redox waves corresponding to the oxidation to the radical cations of the triarylphosphines and irreversible or quasi-reversible waves corresponding to the reduction of the acceptor moieties. The electronic and the fluorescence spectra of these π-conjugated systems, especially push-pull substituted derivatives, exhibit bathochromic shift typical of the extended π-conjugated systems especially in the polar solvent, and the large Stokes shift typical of the crowded triarylphosphines is enhanced by conjugation with the acceptor moiety. 相似文献
54.
Shin‐Ichi Yusa Shigeki Awa Masanori Ito Takeshi Kawase Tadao Takada Kenichi Nakashima Dian Liu Shigeru Yamago Yotaro Morishima 《Journal of polymer science. Part A, Polymer chemistry》2011,49(13):2761-2770
Water‐soluble diblock copolymer, poly(N‐isopropylacrylamide)‐block‐poly(N‐vinyl‐2‐pyrroridone) (PNIPAMm‐b‐PNVPn), was found to associate with fullerene (C60), and thus C60 can be solubilized in water. The 63C60/PNIPAMm‐b‐PNVPn micelle formed a core‐shell micelle‐like aggregate comprising a C60/PNVP hydrophobic core and a thermoresponsive PNIPAM shell. The C60‐containing polymer micelle formation and its thermoresponsive behavior were characterized using light scattering and 1H NMR techniques. The hydrodynamic radius (Rh) of the C60‐bound polymer micelle increased with increasing temperature, which was ascribed to the hydrophobic association between dehydrated PNIPAM shells above lower critical solution temperature (LCST). 1H NMR data suggest that the motion of the PNIPAM block is restricted above LCST due to the dehydration of the PNIPAM shell in water. The generation of singlet oxygen by photosensitization by the C60‐bound polymer micelle was confirmed from photooxidation of 9,10‐anthracenedipropionic acid. Furthermore, DNA was found to be cleaved by visible light irradiation in the presence of the C60‐bound polymer micelle. Therefore, there may be a hope for a pharmaceutical application of the C60‐bound polymer micelle to cancer photodynamic therapy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献
55.
Takashi Kitayama Sayo Ohta Yasushi Kawai Tomoyasu Nakayama Masataka Awata 《Tetrahedron: Asymmetry》2010,21(1):11-15
Tetrahydrozerumbone 2, which has a powerful balmy fragrance, has a stereogenic carbon at C2 and can be easily prepared from zerumbone 1, which is one of the most important materials that displays an NMRDOS character. Reduction of 2 gave two diastereomers 3 and 4; their optically active (>99% ee) alcohols were obtained by lipase-catalyzed stereoselective transesterification of each racemic alcohol. The enantioselectivity of tetrahydrozerumbol does not entirely depend on the hydroxyl position but on the 2-methyl position. Compounds (R)-2 and (S)-2 were obtained by Dess–Martin oxidation of the corresponding alcohols. Interestingly, (R)-2 showed a strong balmy fragrance while (S)-2 had hardly any fragrance. 相似文献
56.
The reuse and recycling of biomass materials can minimize the environmental impact of society, and can help create a sustainable community. Although cellulosic biomass from demolished buildings is a promising resource for recycling, contaminants, such as wood preservatives that likely contain metal oxides, are found in recycled wood dust. These oxides could act as catalysts for the oxidation of organic materials, resulting in spontaneous ignition of large piles of recycled wood dust. Copper(II) oxide (CuO) is major component in wood preservative and plays a catalytic role in the oxidation of cellulose, which could cause spontaneous ignition. The present study focused on the influence of CuO on oxidation of cellulose. The exothermal behavior and mass loss of cellulose/CuO mixtures were investigated. Changes in exothermal behavior and mass loss with an increasing amount of CuO were measured by differential scanning calorimetry and thermogravimetry. In addition, kinetics and spectroanalysis were conducted to determine the catalytic effect of CuO on oxidation of cellulose and help determine the oxidation model of cellulose upon addition of CuO. Results revealed a change in exothermal behavior and increase in mass loss with increasing amounts of CuO. In addition, CuO had a catalytic effect on the oxidation of cellulose, which helped determine the oxidation model of cellulose upon addition of CuO. 相似文献
57.
Nabajyoti Saikia Shigeru Kato Toshinori Kojima 《Journal of Thermal Analysis and Calorimetry》2012,109(1):273-286
Tricalcium aluminate (Ca3Al2O6, C3A) containing 0?C5% of Sn was synthesized by solid-state method, and the products were characterized by XRD technique. Differential thermo-analytical technique (DTA) along with X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to study the hydration behaviour of different C3A samples with and without the presence of gypsum. Results indicate that C3A can accommodate small amount of Sn in its structure and remaining amount forms SnO2. Hydration studies of the synthesized C3A shows that the additions of 0.5 and 1% Sn increase and 2% Sn decrease the reactivity of C3A at the initial period (<3?h) of hydration. Increasing additions of Sn also increase the amounts of amorphous phases and hexagonal calcium aluminate hydrates in the cement pastes. The stabilities of these hydration products also increase with increasing content of Sn in C3A at the experimental conditions. The presence of Sn significantly changes the hydration of C3A and gypsum solid mixture at the initial period of hydration by enhancing the formation of more amounts of AFt and AFm phases. However, at the later stage of hydration (on or after 3?days), the hydration products in C3A and gypsum pastes with and without the presence of Sn are almost similar. 相似文献
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59.
A new sampling method is proposed for projector Monte Carlo (PMC) calculations based on Slater determinants (SD) in singlet states. Using the symmetry of the ?? and ?? electron determinants, the number of configurations to be considered can be about one-half of the original sampling. We applied the new sampling to the PMC-SD calculations of the H2O molecule in the ground state. The results were always improved by the new sampling method both for the equilibrium and for bond-stretched structures. 相似文献
60.
In order to understand the nonlinear effect in a two‐layer system, fully nonlinear strongly dispersive internal‐wave equations, based on a variational principle, were proposed in this study. A simple iteration method was used to solve the internal‐wave equations in order to solve the equations stably. The applicability of the proposed numerical computation scheme was confirmed to agree with linear dispersion relation theoretically obtained from variational principle. The proposed computational scheme was also shown to reproduce internal waves including higher‐order nonlinear effect from the analysis of internal solitary waves in a two‐layer system. Furthermore, for the second‐order numerical analysis, the balance of nonlinearity and dispersion was found to be similar to the balance assumed in the KdV theory and the Boussinesq‐type equations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献