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71.
Tatsuya Morozumi Takashi Kimura Tomomi Ujiie Hiroaki Yonemura Taku Matsuo Hiroshi Nakamura 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(1-2):105-110
The complexation behavior of a series of electron donor–accepter (D–A) covalently linked compounds with cyclodextrins (CyDs) has been reviewed. The structure of these complexes showed rotaxane type conformations, which were investigated by means of 1 H NMR spectrometry. The complex formations induced a fixation of a conformation of guest D–A molecules, and D–A distances were enlarged. Thus, accurate photo-induced charge transfer behaviors can be discussed. 相似文献
72.
Thiophene monomer reacted with ferric chloride in the presence of a variety of fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers [RF-(DOBAA)x-RF] to afford nanometer size-controlled RF-(DOBAA)x-RF oligomers-polythiophene composites [RF-(DOBAA)x-RF/PTh]. RF-(DOBAA)x-RF/PTh nanocomposites thus obtained were demonstrated to have a good dispersibility and stability in methanol to give a transparent brown solution. In addition, these fluorinated nanocomposites were applied to the surface modification of common organic polymers such as poly(methyl methacrylate), and were dispersed regularly above the polymer surface. 相似文献
73.
Treatment of fluoroalkylated alkynes with various aryl halides and arylboronic acids in the presence of Pd(0) in DMF/H2O at 100 °C for 2 h led to the smooth three-component coupling reaction, the corresponding tetrasubstituted alkenes being obtained in high yields stereoselectively. 相似文献
74.
Kaoru Wada Taku Chiba Yutaka Takei Hideko Ishihara Hidetoshi Hayashi Kikuo Onozaki 《Journal of carbohydrate chemistry》2013,32(7):941-965
Abstract Recombinant cytokines generated by bacteria, especially E. coli, are nonglycosylated. To investigate the effects of carbohydrates on their activities, we attempted to develop new cytokines by introduction of carbohydrates. As a model we synthesized neoglycoproteins in which potential immunoregulatory carbohydrates were coupled to bovine serum albumin(BSA). Mannose dimers with C9 spacer, Manα1-6Man, which is reported to be immunosuppressive, and a reference substance Manα1-4Man were synthesized as follows. Benzylidenation of 8-(methoxycarbonyl)octyl α-D-mannopyranoside (10), followed by acetylation and cleavage of the benzylidene acetal, gave a glycosyl acceptor (13) with a free hydroxyl group in the C-4 position. Glycosylation of 13 with acetobromomannose (8), followed by debenzylation, deacetylation, and hydrazidation, gave 8-(hydrazinocarbonyl)octyl 4-O-α-D-mannopyranosyl-α-D-mannopyranoside (1). Total yield of 1 from 10 was 25.1%. Tritylation of 10, followed by acetylation and detritylation, gave a glycosyl acceptor (18) with a free hydroxyl group in the C-6 position. Analogous condensation of 18 with 8, followed by deacetylation and hydrazidation, gave 8-(hydrazinocarbonyl)octyl 6-O-α-D-mannopyranosyl-α-D-mannopyranoside (2). Total yield of 2 from 10 was 22.9%. These mannose dimers were coupled to BSA by the acyl azide method. Using the antibodies against the mannose dimers, an enzyme linked immunosorbent assay (ELISA) was established to measure the small amount of mannose dimers coupled to proteins. These two neoglycoproteins appeared to inhibit the antigen-specific human T cell proliferation over 100 fold more efficiently than free mannose dimers. 相似文献
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77.
Taku Shibue Toshihiro Hirai Dr. Iwao Okamoto Dr. Nobuyoshi Morita Dr. Hyuma Masu Prof. Dr. Isao Azumaya Prof. Dr. Osamu Tamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(38):11678-11688
The total syntheses of tetrapeptides tubulysins D ( 1 b ), U ( 1 c ), and V ( 1 d ), which are potent tubulin polymerization inhibitors, are described. The synthesis of Tuv ( 2 ), an unusual amino acid constituent of tubulysins, includes an 1,3‐dipolar cycloaddition reaction of chiral nitrone D ‐ 6 derived from D ‐gulose with N‐acryloyl camphor sultam (?)‐ 9 employing the double asymmetric induction, whereas the synthesis of Tup ( 20 ), another unusual amino acid, involves a stereoselective Evans aldol reaction of (Z)‐boron enolate generated from (S)‐4‐isopropyl‐3‐propionyl‐2‐oxazolidinone with N‐protected phenylalaninal and a subsequent Barton deoxygenation protocol. We accomplished the total syntheses of tubulysins U ( 1 c ) and V ( 1 d ) by using these methodologies, in which the isoxazolidine ring was used as the effective protective group for γ‐amido alcohol functionality. Furthermore, to understand the structure‐activity relationship of tubulysins, we synthesized tubulysin D ( 1 b ) and cyclo‐tubulysin D ( 1 e ) from 2 ‐Me and 20 , and ent‐tubulysin D (ent‐ 1 d ) from ent‐ 2 ‐Me and ent‐ 20 , respectively. The preliminary results regarding their biological activities are also reported. 相似文献
78.
TiO2 nanoparticles were modified with porphyrin derivatives, 5-[4-benzoic acid]-10,15,20-tris[3,5-di-tert-butylphenyl]-21H,23H-porphyrin (Ar-H2P-COOH), 5-[4-benzoic acid]-10,20-tris[3,5-di-tert-butylphenyl]-21H,23H-porphyrin (H-H2P-COOH), and 5,10,15,20-tetra[4-benzoic acid]-21H,23H-porphyrin (H2P-4COOH). The porphyrin-modified TiO2 nanoparticles were deposited on nanostructured OTE/SnO2 electrode together with nanoclusters of fullerene (C60) in acetonitrile-toluene (3/1, v/v) using an electrophoretic deposition technique to afford the porphyrin-modified TiO2 composite electrode denoted as OTE/SnO2/(porphyrin-modified TiO2 nanoparticle+C60)n. The porphyrin-modified TiO2 composite electrodes have efficient light absorbing properties in the visible region, exhibiting the photoactive response under visible light excitation using redox couple. The incident photon-to-photocurrent efficiency (IPCE) values of supramolecular nanostructured electrodes of porphyrin-modified TiO2 nanoparticles with fullerene [OTE/SnO2/(Ar-H2P-COO-TiO2+C60)n, OTE/SnO2/(H-H2P-COO-TiO2+C60)n, and OTE/SnO2/(H2P-4COO-TiO2+C60)n] are much larger than those of the reference systems of porphyrin-modified TiO2 nanoparticles without C60 [OTE/SnO2/(Ar-H2P-COO-TiO2)n, OTE/SnO2/(H-H2P-COO-TiO2)n, and OTE/SnO2/(H2P-4COO-TiO2)n]. In particular, the maximum IPCE value (41%) is obtained for OTE/SnO2/(H-H2P-COO-TiO2+C60)n under the bias potential of 0.2 V versus SCE. This indicates that the formation of supramolecular complexes between porphyrins and fullerene on TiO2 nanoparticles plays an important role in improvement of the light energy conversion properties. 相似文献
79.
Wang YF Cheng SS Tsujimura S Ikeda T Kano K 《Bioelectrochemistry (Amsterdam, Netherlands)》2006,69(1):74-81
Bioelectrocatalytic oxidation of acetate was investigated under anaerobic conditions by using Escherichia coli K-12 (IFO 3301) cells cultured on aerobic media containing poly-peptone, glucose or acetate as the sole carbon source. It was found that all E. coli cells cultured on the three media work as good catalysts of the electrochemical oxidation of acetate as well as glucose with Fe(CN)6(3-), 2,3-dimethoxy-5-methyl-1,4-benzo-quinone (Q0), 2,6-dichloro-indophenol, or 2-methyl-1,4-naphthoquinone as artificial electron acceptors (mediators). Acetate-grown E. coli cells exhibited the highest relative activity of the acetate oxidation against the glucose oxidation. On the other hand, all the artificial electron acceptors used work as inhibitors for the catalytic oxidation of acetate at increased concentrations. The inhibition phenomenon can be interpreted in terms of competitive substrate inhibition as a whole. Apparent values of Michaelis constant, catalytic constant, and inhibition constant were evaluated by amperometric methods. Q0 is an effective artificial mediator as evidenced by a large reaction rate constant between the cell and Q0 at least at low concentrations (<50 microM). However, Fe(CN)6(3-) is a promising mediator in biosensor applications because the inhibition constant is very large and it works as an electron acceptor even under aerobic conditions. 相似文献
80.
Inokuchi T Takiuchi H Moriwaki Y Ka T Takahashi S Tsutsumi Z Shima H Hirota S Yamamoto T 《Magnetic resonance imaging》2006,24(10):1389-1393
A 35-year-old woman was referred to our institution for additional examinations to evaluate bilateral suprarenal masses incidentally found on abdominal ultrasonographic images obtained during an annual medical health checkup. Our computed tomographic scans showed bilateral and well-circumscribed low-density suprarenal masses, while MRI revealed the tumors to be heterogeneous with low intensity on T1-weighted images and high intensity on T2-weighted images. A laparoscopic adrenalectomy was performed under the suspicion of a malignant tumor, such as a malignant fibrous histiocytoma. Pathologic findings indicated a retroperitoneal ancient schwannoma of two histologic types: Antoni A and Antoni B. We considered that elucidation of the characteristic features of a schwannoma would provide helpful preoperative information for diagnosis. 相似文献