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11.
A novel coordination gelator exhibits reversible chromatic and sol-gel phase-transition phenomena triggered by thermal and chemical stimuli. 相似文献
12.
Functional porous coordination polymers 总被引:18,自引:0,他引:18
The chemistry of the coordination polymers has in recent years advanced extensively, affording various architectures, which are constructed from a variety of molecular building blocks with different interactions between them. The next challenge is the chemical and physical functionalization of these architectures, through the porous properties of the frameworks. This review concentrates on three aspects of coordination polymers: 1). the use of crystal engineering to construct porous frameworks from connectors and linkers ("nanospace engineering"), 2). characterizing and cataloging the porous properties by functions for storage, exchange, separation, etc., and 3). the next generation of porous functions based on dynamic crystal transformations caused by guest molecules or physical stimuli. Our aim is to present the state of the art chemistry and physics of and in the micropores of porous coordination polymers. 相似文献
13.
Kato S Matsumoto T Ishi-i T Thiemann T Shigeiwa M Gorohmaru H Maeda S Yamashita Y Mataka S 《Chemical communications (Cambridge, England)》2004,(20):2342-2343
Novel donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) type 2,1,3-benzothiadiazole fluorescent dyes connected to the N,N-diarylamino terminus via various type pi-conjugate spacers exhibits large two-photon absorption cross-sections and high fluorescent quantum yields in orange-red color. 相似文献
14.
15.
Shin-ichiro Fujita Shuhei Moribe Yoshinori Kanamori Nobutsune Takezawa 《Reaction Kinetics and Catalysis Letters》2000,70(1):11-16
The CuO crystallite size of the catalysts obtained from aurichalcite greatly depends on the heating rate of calcination for highly active and selective Cu/ZnO catalyst was prepared by reduction with methanol at 443 K for 17 h. 相似文献
16.
Yoshio Kitaoka Hidekazu Mukuda Shin-ichiro Tabata Akira Iyo 《Journal of Physics and Chemistry of Solids》2011,72(5):486-491
We reexamine the novel phase diagrams of antiferromagnetism (AFM) and high-Tc superconductivity (HTSC) for a disorder-free CuO2 plane based on an evaluation of local hole density (p) by site-selective Cu-NMR studies on multilayered copper oxides. Multilayered systems provide us with the opportunity to research the characteristics of the disorder-free CuO2 plane. The site-selective NMR is the best and the only tool used to extract layer-dependent characteristics. Consequently, we have concluded that the uniform mixing of AFM and SC is a general property inherent to a single CuO2 plane in an underdoped regime of HTSC. The T=0 phase diagram of AFM constructed here is in quantitative agreement with the theories in a strong correlation regime which is unchanged even with mobile holes. This Mott physics plays a vital role for mediating the Cooper pairs to make Tc of HTSC very high. By contrast, we address from extensive NMR studies on electron-doped iron-oxypnictides La1111 compounds that the increase in Tc is not due to the development of AFM spin fluctuations, but because the structural parameters, such as the bond angle α of the FeAs4 tetrahedron and the a-axis length, approach each optimum value. Based on these results, we propose that a stronger correlation in HTSC than in FeAs-based superconductors may make Tc higher significantly. 相似文献
17.
Shin-ichiro Hayashi Munenori Yoshioka Shuji Usui Kiyofumi Haneda Takahiro Kondo Kim B. McAuley Takahiro Tominaga 《Radiation Physics and Chemistry》2010,79(7):803-808
In radiotherapy treatment, polymer gel dosimetry can be used for verifying three-dimensional (3D) dose distributions. Gelatin is generally used as a gelling agent in the dosimeters. In this paper, another role of gelatin in a methacrylic-acid-based gel dosimeter (MAGAT) is investigated. Temperature increases due to exothermic polymerization in the irradiated gel are measured directly. Dose–R2 responses are also obtained using MRI. It is shown that no appreciable increases in either temperature or R2 are observed in MAGAT dosimeters made without gelatin, and that significant temperature and R2 increases are observed when very low gelatin concentrations are used. These results indicate that gelatin is an important enabler for radiation-induced free-radical polymerization in methacrylic-acid-based gels. When gelatin is replaced by amino acids, changes in temperature are observed, along with small changes in R2. The resulting dosimeter solutions remain transparent because the polymer does not precipitate as it does in regular MAGAT dosimeters containing gelatin. When the amino acids are replaced by acids without amino groups, no temperature or R2 changes are observed, indicating that no polymer forms. These results show that amino groups (and possibly other functional groups) on the gelatin catalyze the radiation-induced free-radical polymerization that occurs in MAGAT dosimeters. 相似文献
18.
DNA quantification has made its mark in pharmaceutical analysis and the life sciences. In particular, in the quality control of nucleic acid drugs and the detection and quantification of genetically modified organisms, evaluation of the DNA degradation rate has become imperative. In this study, by using high-performance liquid chromatography with an anion-exchange column, we established a method for the separation and quantification of DNA fragments in mixed DNA samples. By using a NaCl concentration gradient, DNA fragments in mixed DNA sample were separated well. A calibration curve from 0.05 to 12.4 ng μL?1 was obtained with high linearity and the correlation coefficient was 0.9999. The limit of detection was 0.02 ng μL?1 and the limit of quantification was 0.06 ng μL?1 for S/N = 3 or S/N = 10, respectively. The relative standard deviation was less than 2 % in the measurement of peak area repeatability. The recovery of approximately 1 ng μL?1 of a specific DNA spiked in a mixed DNA sample was 99.9 ± 3.6 %. The method was able to measure the degradation rate of 600 bp DNA with a variation of approximately 1 %. 相似文献
19.
Hidetsura Cho Yoshio Nishimura Yoshizumi YasuiSatoshi Kobayashi Shin-ichiro Yoshida Eunsang Kwon Masahiko Yamaguchi 《Tetrahedron》2011,67(14):2661-2669
Synthesis of novel 4-unsubstituted dihydropyrimidines (DPs) was performed. Subsequently, a variety of 4-unsubstituted 1,4(3,4)-DPs with amino moieties at position-2 were obtained in excellent yields by activation of position-2 owing to regioselective alkoxycarbonylation at position-3 of the DP skeleton. 3-Oxo-2-phenyl-2,3,5,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrimidine was obtained using phenylhydrazine instead of amines. Individual tautomers of 1,4(3,4)-DP were observed in the 1H NMR spectra of one derivative depending on temperature and concentration. On the other hand, only 1,4-DP was found in the solid state by single-crystal X-ray crystallography. 相似文献
20.
Sakai N Lista M Kel O Sakurai S Emery D Mareda J Vauthey E Matile S 《Journal of the American Chemical Society》2011,133(39):15224-15227
Facile access to complex systems is crucial to generate the functional materials of the future. Herein, we report self-organizing surface-initiated polymerization (SOSIP) as a user-friendly method to create ordered as well as oriented functional systems on transparent oxide surfaces. In SOSIP, self-organization of monomers and ring-opening disulfide exchange polymerization are combined to ensure the controlled growth of the polymer from the surface. This approach provides rapid access to thick films with smooth, reactivatable surfaces and long-range order with few defects and high precision, including panchromatic photosystems with oriented four-component redox gradients. The activity of SOSIP architectures is clearly better than that of disordered controls. 相似文献