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61.
Akio Teramoto Shozaburo Hiratsuka Yasunori Nishijima 《Journal of Polymer Science.Polymer Physics》1967,5(1):37-45
The fluorescence polarization method has been used to study the micro-Brownian motion of a terminal segement of a polymer chain in concentrated solutions. A new apparatus for determining the fluorescence intensity and its polarization degree was designed. By using this apparatus, the rotational relaxation time 〈ρ〉 of the terminal segment of the fluorescent conjugates of polyacrylamide in aqueous polyacrylamide solutions was obtained as a function of polymer concentration from 0 to 65%, molecular weight of the conjugate from 3.5 × 104 to 3 × 105, and temperature from 10 to 30°C. The logarithm of 〈ρ〉 increased approximately linearly with increasing polymer concentration. This increase in 〈ρ〉, amounting to a factor of 20 times, was less marked than that in macroscopic viscosity. At concentrations less than 30%, 〈ρ〉 depended appreciably on the molecular weight of the conjugate. 相似文献
62.
Guang Shao Akihiro Orita Prof. Dr. Koji Nishijima Kanako Ishimaru Makoto Takezaki Prof. Dr. Kan Wakamatsu Prof. Dr. Rolf Gleiter Prof. Dr. Junzo Otera Prof. Dr. 《化学:亚洲杂志》2007,2(4):489-498
A variety of arylethynylsilanes (Ar‐C?C? C6H4? C?C)nSiMe4?n were prepared successfully by reaction of the corresponding chlorosilanes Me4?nSiCln with Ar? C?C? C6H4? C?CM (M=Li, MgBr), which was prepared by treatment of ethynyl(diarylethyne)s Ar? C?C? C6H4? C?CH with BuLi or MeMgBr. The ethynyl(diarylethyne)s were readily prepared in good yields by the double‐elimination method: addition of lithium hexamethyldisilazide to a mixture of ArCH2SO2Ph, TMS? C?C? C6H4? CHO, and ClP(O)(OEt)2, followed by desilylation. In the tetrakis(arylethynyl)silanes (Ar? C?C? C6H4? C?C)4Si thus prepared, through‐space conjugation of four triple bonds on the silicon atom emerges as a result of participation of the silicon orbitals in the acetylenic π orbitals. This participation enhances the emissive quantum yields of arylethynylsilanes with an increase in the number of arylethynyl moieties on silicon: quantum yields of emission (ΦF) of 0.72 for (MeOC6H4? C?C? C6H4? C?C)4Si, 0.53 for (MeOC6H4? C?C? C6H4? C?C)2SiMe2, and 0.47 for MeO‐C6H4? C?C? C6H4? C?CSiMe3 were obtained. Although this enhancement effect was also observed in the phenylethynylarylsilane (MeOC6H4? C?C? C6H4)2SiMe2, the bis(arylethynyl)disilane (MeOC6H4? C?C? C6H4? C?C‐SiMe2)2 exhibited non‐enhanced emission. 相似文献
63.
The possibility of multi-valued optical disk memory by using a convex-shaped recording mark fabricated by two-photon absorption is investigated. We fabricate a numerical model for convex-shaped recording marks and evaluate the signal characteristics in terms of the signal-to-noise ratio (SNR). The numerical results show that 6 bit data can be realized when the acceptable average SNR is 2 and a length of the mark is 4T. 相似文献
64.
65.
Hisashi Honda Shinshin Kyo Yousuke Akaho Satoshi Takamizawa Hiromitsu Terao 《Hyperfine Interactions》2010,197(1-3):275-285
H/D isotope effects onto 79Br NQR frequencies of piperidinium p-bromobenzoate were studied by deuterium substitution of hydrogen atoms which form two kinds of N–H?O type hydrogen bonds, and the isotope shift of ca. 100 kHz were detected for a whole observed temperature range. In addition, 1H MAS NMR spectra measurements of piperidinium and pyrrolidinium p-bromobenzoate were carried out and little isotope changes of NMR line shape were detected. In order to reveal effects of molecular arrangements into the obtained isotope shift of NQR frequencies, single-crystal X-ray measurement of piperidinium p-bromobenzoate-d2 and density-functional-theory calculation were carried out. Our estimation showed the dihedral-angle change between piperidine and benzene ring contributes to isotope shift rather than those of N–H lengths by deuterium substitution. 相似文献
66.
Hamura T Ibusuki Y Uekusa H Matsumoto T Siegel JS Baldridge KK Suzuki K 《Journal of the American Chemical Society》2006,128(31):10032-10033
We report herein the syntheses of dodecamethoxytricyclobutabenzene (TCBB) 1 and hexaoxo-TCBB 2, a class of molecules with structural and theoretical interest. The preparation is based on the 3-fold [2 + 2] cycloadditions of benzyne and ketene silyl acetals (KSAs), where the selectively protected 2-iodophloroglucinol derivative served as a synthetic equivalent of benztriyne I, allowing rapid and regioselective annulation of fully functionalized four-membered rings. Structural study on the former compound showed that the C-C bond lengths in the central benzene ring were essentially the same. 相似文献
67.
Matsuda H Fujimoto Y Ito S Nagasawa Y Miyasaka H Asahi T Masuhara H 《The journal of physical chemistry. B》2006,110(3):1091-1094
Femtosecond near-infrared laser microscope was developed with a home-built cavity-dumped chromium:forsterite laser as a light source centered at 1.26 microm. Optimization of the pulse duration achieved 35 fs fwhm at the sample position of the microscope after passing through a 100x objective. This system was applied to the detection of multiphoton fluorescence of some organic microcrystals. Excitation intensity dependence and the interferometric autocorrelation detection of the fluorescence clearly demonstrated that simultaneous three- and four-photon absorption processes are responsible for the production of the excited state for perylene and anthracene microcrystals, respectively. The spatial resolution along the optical axis and its dependence on the order of the multiphoton process were also discussed. 相似文献
68.
Sawada T Nishiyama Y Tabuchi W Ishikawa M Tsutsumi E Kuwahara Y Shosenji H 《Organic letters》2006,8(10):1995-1997
[reaction: see text] Tetramethoxy[2.1.2.1]metacyclophane ([2.1.2.1]MCP) was prepared by the pinacol coupling reaction of diphenylmethane dialdehyde. The treatment of [2.1.2.1]MCP with trimethylsilyl chloride and sodium iodide yielded two unexpected calixarene derivatives, cone (hemisphere) and 1,2-alternate types, instead of octahydroxy[2.1.2.1]MCP. The X-ray structure of the cone-type derivative and its inclusion property with acetonitrile were also discussed. 相似文献
69.
Yousuke Ooyama 《Tetrahedron》2010,66(40):7954-533
Three heterocyclic quinol-type fluorophores with benzo[c]carbazol-6-one skeleton or benzo[b]naphtho[1,2-d]furan-6-one skeleton, 9-dibutylamino-5-hydroxy-5-phenyl-5,7-dihydro-benzo[c]carbazol-6-one (5a), 7-butyl-9-dibutylamino-5-hydroxy-5-phenyl-5,7-dihydro-benzo[c]carbazol-6-one (5b) and 9-dibutylamino-5-hydroxy-5-phenyl-5H-benzo[b]naphtho[1,2-d]furan-6-one (6c) have been synthesized and their photophysical properties have been investigated in solution and in the solid state. The fluorescence quantum yield (Φ) increases in the order of 5b (0.35)<5a (0.41)<6c (0.74) in 1,4-dioxane. On the other hand, the Φ value in the solid state increases in the order of 5a<<6C (0.03)<5b (0.07), which are much smaller than those in 1,4-dioxane. To elucidate the effects of molecular and crystal structures on the solid-state fluorescence properties, we have performed the semi-empirical molecular orbital calculations (AM1 and INDO/S) and X-ray crystallographic analysis. It was found that the formation of a continuous intermolecular hydrogen bonding between adjacent fluorophores is observed in the crystal of 5a, which is considered to cause a drastic fluorescence quenching in the solid state. 相似文献
70.
We describe the characterization of polyhydroxyalkanoate (PHA)-producing bacteria isolated from an ammunition-polluted soil in Kitakyushu City, Japan. Over 270 strains were evaluated for PHA accumulation based on a colony staining method using Nile red. Of these, nine strains were selected based on the intensity of Nile red fluorescence and the cells were quantitatively analyzed for PHA by gas chromatography. PHA accumulation was observed in five strains, all of which are inferred to be close to the Bacillus cereus group according to 16S rDNA sequence analysis. Interestingly, these strains produced a PHA copolymer, poly(3-hydroxybutyrae-co-3-hydroxyvalerate) [P(3HB-co-3HV)], with a 3HV fraction up to 2 mol% with glucose as a carbon source. Further characterization was performed on one isolate, B. cereus YB-4. Gel permeation chromatography analysis revealed that the number of average molecular weights of PHA accumulated in B. cereus YB-4 drastically changed from 722,000 to 85,000 over a 72-h cultivation period. Furthermore, the PHA synthase genes were cloned and the deduced amino acid sequences were determined. This study provides new insights into PHA biosynthesis by members of the B. cereus group. 相似文献