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711.
712.
Poly[4,6‐bis(dodecylthio)‐1,3‐phenylene‐alt‐2‐methyl‐1,3‐phenylene] (Poly‐S) was synthesized via Suzuki–Miyaura coupling of 1,3‐dibromo‐2,6‐bis(dodecylthio)benzene and 2‐methyl‐1,3‐phenylenebis(pinacol borate). After quantitative oxidation of the pendant sulfide moiety to the sulfoxide derivative (Poly‐SO), the m‐linked benzene rings were fused via intramolecular ring‐closing condensation with excess triflic acid to form the corresponding poly(sulfonium cation) (Poly‐S+) with a helical structure. Poly‐S+ was quite soluble in non‐polar solvents due to the long alkyl dodecyl chain. The Poly‐S+ film, especially the film cast from its acetone solution, gave a polarized optical micrograph, suggesting an oriented structure of the helical poly(sulfonium) derivative. The X‐ray diffraction pattern of the film supported a hexagonal columnar packing of the polymer. The polysulfonium derivative in the film state was converted to the corresponding poly(thiaheterohelicene) ( Poly‐TH ) via the dealkylation with a basic potassium hydroxide methanol solution or pyridine. The Poly‐TH film was doped with iodine. Its conductivity was enhanced about 30 times when compared to that of the undoped film. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
713.
714.
Naoki Kanoh Aya Asami Makoto Kawatani Kaori Honda Saori Kumashiro Hiroshi Takayama Siro Simizu Tomoyuki Amemiya Yasumitsu Kondoh Satoru Hatakeyama Keiko Tsuganezawa Rei Utata Akiko Tanaka Shigeyuki Yokoyama Hideo Tashiro Hiroyuki Osada 《化学:亚洲杂志》2006,1(6):789-797
We have developed a unique photo‐cross‐linking approach for immobilizing a variety of small molecules in a functional‐group‐independent manner. Our approach depends on the reactivity of the carbene species generated from trifluoromethylaryldiazirine upon UV irradiation. It was demonstrated in model experiments that the photogenerated carbenes were able to react with every small molecule tested, and they produced multiple conjugates in most cases. It was also found in on‐array immobilization experiments that various small molecules were immobilized, and the immobilized small molecules retained their ability to interact with their binding proteins. With this approach, photo‐cross‐linked microarrays of about 2000 natural products and drugs were constructed. This photo‐cross‐linked microarray format was found to be useful not merely for ligand screening but also to study the structure–activity relationship, that is, the relationship between the structural motif (or pharmacophore) found in small molecules and its binding affinity toward a protein, by taking advantage of the nonselective nature of the photo‐cross‐linking process. 相似文献
715.
Leukemia and lymphoma cells are much more sensitive to Merocyanine 540 (MC540)-mediated photodynamic therapy (PDT) than normal pluripotent hematopoietic stem cells and normal colony forming unit-granulocyte/macrophage progenitors (CFU-GM). By contrast, most solid tumor cells are only moderately sensitive to MC540-PDT. The limited activity against solid tumor cells has detracted from MC540's appeal as a broad-spectrum purging agent. We report here that noncytotoxic concentrations of amifostine (Ethyol, Ethiofos, WR-2721) and amphotericin B used either alone or in combination potentiate the MC540-sensitized photoinactivation of leukemia cells, wild-type small cell lung cancer cells and cisplatin-resistant small cell lung cancer cells. Amphotericin B also enhances the MC540-sensitized photoinactivation of normal CFU-GM, whereas amifostine protects CFU-GM against the cytotoxic action of MC540-PDT. The yield of CD34-positive normal hematopoietic stem and progenitor cells is only minimally diminished by pretreatment with amifostine, amphotericin B or combinations of amifostine plus amphotericin B. Purging protocols that combine MC540-PDT with amifostine or with amifostine plus amphotericin B could offer a simple and effective approach to the purging of autologous stem cell grafts that are contaminated with solid tumor cells or the purging of stem cell grafts from heavily pretreated leukemia patients that contain reduced numbers of normal stem and progenitor cells and, therefore, can ill afford additional losses caused by purging. 相似文献
716.
Noboru Ohta Toshihiko Oka Katsuaki Inoue Naoto Yagi Satoru Kato Ichiro Hatta 《Journal of Applied Crystallography》2005,38(2):274-279
The cell membrane complex in the cuticle of a human hair fibre or a rat whisker is composed of three layers, that is, β, δ and β layers. The X‐ray diffraction technique is a powerful tool to investigate the pathway of aqueous molecules and ions across the cuticle. Small‐angle scattering experiments using a micro X‐ray beam, which can be applied to a cuticle of 5 µm thickness, provide the structural information on the cell membrane complex without interference from other structures. Taking into account the variation of thickness in the δ and β layers, the overall features of the diffraction profile in a small‐angle region can be explained satisfactorily. The method makes it possible to analyse the structure of β, δ and β layers without assuming an ambiguous background in the diffraction profile, and was used for the analysis of a human hair fibre and a rat whisker. In a rat whisker, the X‐ray diffraction was stronger and the variation in the layer thickness smaller than in a human hair fibre. This may be due to the fact that the rat whisker had not been washed with soap or cosmetically treated, whereas the variation may depend on the lipids or the proteins that each species naturally has. It is proposed that the method represents convenient tool for quantitative analysis to estimate the thickness of δ and β layers in the cell membrane complex. 相似文献
717.
Noriyuki Hatae Ichiro Suzuki Tominari Choshi Satoshi Hibino Chiaki Okada Eiko Toyota 《Tetrahedron letters》2014
Steric and enthalpic effects of substituents on diene moieties play a crucial role in intramolecular cycloaddition reactions. Allenyl 2-halogenated-3-vinylcyclohex-2-enyl ethers underwent a tandem [4+2] cycloaddition/aromatization reaction to afford the corresponding tetrahydro-3H-naphtho[1,8-bc]furan compound in high yield. 相似文献
718.
719.
720.
Ichiro Yonenaga Toshinori Taishi Hideaki Ise Yu Murao Kaihei Inoue Takayuki Ohsawa Yuki Tokumoto Yutaka Ohno Yoshio Hashimoto 《Physica B: Condensed Matter》2012,407(15):2932-2934
Local vibrations of oxygen in Ge crystals grown by the Czochralski method adopting liquid-B2O3 encapsulation and GeO2 powder doping were investigated by Fourier-transform infrared spectroscopy. Strong absorption peaks at 855 cm−1, originating in local vibration of interstitially dissolved oxygen Oi as Ge–Oi–Ge quasi-molecules, developed depending on the doped amount of GeO2. Similarly, an absorption peak related to the combined vibration of Ge–Oi–Ge was found at 1264 cm−1 and the conversion factor from the peak intensity to the oxygen concentration was evaluated to be 1.15×1019 cm−2. By prolonged annealing at 350 °C an absorption peak developed at 780 cm−1, indicating formation of oxygen-related thermal donors. From the variations of carrier density and oxygen concentration, one donor was found to possess about 15 Oi atoms. 相似文献