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331.
Because of their potential application as new electrical materials that depend on their redox properties, π-conjugated polymers and oligomers have attracted much attention. Polyanilines, which are chemically stable, are one of the promising classes of conducting π-conjugated polymers. Polyanilines exist in three different discrete redox forms, which include the fully reduced leucoemeraldine, the semioxidized emeraldine, and the fully oxidized pernigraniline base form. The redox-active 1,4-phenylenediamine (PD) and 1,4-benzoquinonediimine, unit molecules of the emeraldine base form, can bind to transition metals to afford novel conjugated complexes. The introduction of metal centers into π-conjugated polymers is expected to dramatically change their functions. In this Account, we describe our ongoing research into the construction of conjugated complexes with redox-active π-conjugated polyanilines and 1,4-benzoquinonediimines. These systems can form architecturally controlled functionalized systems that depend on their dynamic redox properties, resulting in highly selective and versatile electron-transfer reactions and functionalized materials. Complexation with metals (Pd, V, Cu, etc.) occurred via the two nitrogen atoms of the quinonediimine moiety of the emeraldine base form of poly(o-toluidine) to afford the single-strand or cross-linked network conjugated complexes with d,π-conjugation. The complexation of the redox-active π-conjugated 1,4-benzoquinonediimines, unit molecules of the emeraldine base form, with palladium(II) compounds yielded a variety of conjugated complexes. Through regulation of the coordination mode of the quinonediimine moiety, we were able to architecturally control the formation of conjugated bimetallic, polymeric, or macrocyclic complexes. Complexation modulated the redox function of the quinonediimine moiety. Introduced metals act as a metallic dopant, and the complexed quinonediimine is stabilized as an electron sink. Furthermore, chirality could be induced into a π-conjugated backbone through complexation with optically active transition compounds, resulting in chiral d,π-conjugated complexes. We could also modulate the functional properties of conjugated complexes based on the redox states of the redox-active π-conjugated moieties. We also demonstrated how complexes with redox-active π-conjugated molecules can control the architecture of redox-functionalized systems through the metal imido bonds of these systems. Using the one-pot preparation of (arylimido)vanadium(V) compounds from the corresponding anilines, we synthesized binuclear complexes with axial chirality and trinuclear complexes with a tridendritic centrosymmetric structural motif. Such structures showed a strong tendency to self-assemble. 相似文献
332.
Diffuse reflectance (DF) spectra in the 1250-2500 nm region were measured in vivo for the skin of the forehead, cheek, jaw, elbow, volar forearm, palm, knee, and heel of seven healthy volunteers, using a Fourier transform near-infrared (FT-NIR) spectrophotometer with a fiber-optic probe. Apparent regional differences of water content in the skin, as estimated from the diffuse reflectance NIR spectra, are discussed in relation to the influence of measurement depth. The NIR spectra were collected with or without a 300 microm gap between the fiber-optic probe and the skin surface. For comparison, in vitro NIR spectra of stratum corneum sheets equilibrated at 41, 50, 63, and 81% relative humidity, at 25 degrees C, were also obtained. There was a difference in the ratio of the two water bands centered near 1450 nm and 1900 nm between the contact and non-contact measurements. In addition, regional differences of water content calculated from the peak height of the 1900 nm water band, which was normalized to the peak height of the 2175 nm amide band, were compared. The results of Monte Carlo simulation indicated that the apparent regional differences arise at least in part from differences in the measurement depth due to differences in specular reflection at the skin surface and in the thickness of the stratum corneum. 相似文献
333.
Hitomi Ohara Masafumi Yamamoto Akihisa OnogiKoichi Hirao Shiro Kobayashi 《Journal of Bioscience and Bioengineering》2011,111(1):19-21
n-Butyl d- and l-lactates (BuDLa and BuLLa) were incubated with immobilized lipase. 1H-NMR showed that BuDLa reacted to oligomers, while BuLLa did not react. A mixture containing 90.4% of BuLLa and 9.6% of BuDLa was incubated with the enzyme for 72 h, then distilled. The purity of BuLLa increased to 98.6%. 相似文献
334.
Daisuke Saio Toru Amaya Toshikazu Hirao 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(1):79-84
Polyaniline/Pd nanoparticles were synthesized via ligand exchange. Pre-prepared water soluble starch/Pd nanoparticles were
treated with polyaniline, and washed with water, leading to the small and well-dispersed polyaniline/Pd nanoparticles. The
redox state of polyaniline was preserved during the ligand exchange reaction.
相似文献
Toshikazu HiraoEmail: |
335.
336.
337.
Youichirou Kaga Mark I. Jones Kiyoshi Hirao Shuzo Kanzaki 《Journal of Materials Science》2007,42(2):699-704
Y-α-SiAlONs with elongated grains were fabricated via a reaction-bonding process using starting compositions containing excess
oxides in the form of Y2O3 and SiO2. The density of post-sintered specimens reached a maximum value with compositions containing 2 mass% excess oxides, although
conventionally sintered materials of this composition were not fully dense. However for compositions containing smaller amounts
of excess oxides, the density of the specimen fabricated via a reaction-bonding process was lower than that via a conventional
process. In these samples it is thought that liquid phase sintering was difficult to be achieve during the post-sintering
process, since the amount of SiO2 contained in the starting powder was lower and the Al2O3 in the starting composition was consumed for the production of β-SiAlON during nitridation. There was also a decrease in
density of the reaction-bonded materials with further increases in the amounts of additional oxides. For these samples the
compacts could not be densified uniformly, because of non-uniformity of the phase composition in the nitrided compacts. The
dense reaction bonded α-SiAlON with elongated grains, fabricated from compositions with 2 mass% excess oxides exhibited both
high fracture toughness and high hardness. 相似文献
338.
339.
Setsuhisa Tanabe Naohiro Saga Kazuyuki Hirao Teiichi Hanada† 《Journal of the American Ceramic Society》1990,73(6):1733-1736
SiO2 –Al2 O3–Eu2 O3 glasses were prepared for the composition 50siO2 ·(50 – x )Al2 O3·x Eu2 O3 , and their density, sound velocity, and elastic modulus were measured. The chemical shift of the AIK a band emission spectra and the isomer shift of 151 Eu by Mössbauer effect were obtained to determine the coordination states of Al3+ and Eu3+ ions in these glasses. It was found that the coordination number of Eu3+ ions was 12 and that the average coordination number of A13+ ions was almost 5 in these glasses. By introducing Eu2 O3 , the packing of constituent ions was strongly enhanced and the elastic modulus increased in this system. The compositional dependence of the molar volume and elastic modulus were explained by these states of high coordination number for Eu3+ and low coordination number for Al3+ ions compared with those in the corresponding M2 O3 crystals. 相似文献
340.
J Gofuku H Shiozaki Y Doki M Inoue M Hirao N Fukuchi M Monden 《Canadian Metallurgical Quarterly》1998,78(8):1095-1101
The soluble fragment of E-cadherin protein (S-ECD) is reported to be increased in the peripheral blood of cancer patients. In this study, we investigated the clinical significance of serum S-ECD in 81 patients with gastric cancer. The amount of serum S-ECD was significantly higher in the gastric cancer patients (4735 +/- 2310 ng ml(-1)) than in healthy volunteers (2515 +/- 744 ng ml(-1)). With the normal range cut-off at average +2 s.d., 67% patients showed abnormally high serum S-ECD levels. This frequency was significantly higher than that of other tumour markers, such as CEA (4.4%) or CA19-9 (13.3%). However, there was no significant correlation between the amount of S-ECD and clinicopathological factors. Serum S-ECD might be derived from cancer tissue, as removal of cancers by surgical treatment results in quick decline of the serum S-ECD and S-ECD can be detected by immunoblot in cancer tissues but not in normal epithelium. The serum S-ECD amount was compared with the E-cadherin expression in cancer tissues, which were classified into those showing preserved (+), partially reduced (+/-) or lost (-) expression. Interestingly, E-cadherin (+/-) tumours showed higher serum S-ECD levels than the other types, and a higher amount of S-ECD in the immunoblot analysis. Thus, the serum level of S-ECD may serve as an excellent tumour marker with high sensitivity. Furthermore, analysis of S-ECD in serum and cancer tissue can offer clues for elucidating the mechanism of reduction of E-cadherin expression in cancer cells. 相似文献