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91.
Tomohito Morosaki Tsubasa Suzuki Wei‐Wei Wang Shigeru Nagase Takayoshi Fujii 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(36):9723-9725
Electronic effects on the central carbon atom of carbone, generated by the replacement of the SIV ligand of carbodisulfane (CDS) with other chalcogen ligands (Ph2E, E=S or Se), were investigated. The carbones Ph2E→C←SPh2(NMe) [E=S( 1 ) or Se( 2 )] were synthesized from the corresponding salts, and their molecular structures and electronic properties were characterized. The carbone 2 is the first carbone containing selenium as the coordinated atom. DFT calculations revealed the electronic structures of 1 and 2 , which have two lone pairs of electrons at the carbon center. The trend in HOMO energy levels, estimated by cyclic voltammetry measurements, for the carbones and CDS follows the order of 2 > 1 >CDS. Analysis of a doubly protonated dication and trication complex revealed that the central carbon atom of 2 behaves as a four‐electron donor. 相似文献
92.
Diversity oriented synthesis of conjugate dienes and alkenylcyclopropanes by the sequential reactions using silyl group-substituted titanium carbene complexes was studied. Dienylsilanes were obtained by the olefination of carbonyl compounds with γ-silylvinylcarbene complexes. Cyclopropanation of 1-alkenes with the vinylcarbene complexes produced (E)-(β-silylvinyl)cyclopropanes with high stereoselectivity. The reaction of β-(trialkylsilyl)carbene complexes with zinc alkoxides of homopropargyl alcohols produced 6-silyl-3,5-hexadien-1-ols with high regio- and stereoselectivity. The (E)-alkenylsilanes thus obtained were transformed into a range of unsaturated compounds by the palladium-catalyzed or copper(I)-promoted cross-coupling with organic halides with retention of configuration. 相似文献
93.
Xiaolei Wang Miho Emoto Atsushi Sugimoto Yusuke Miyake Kaori Itto Mitsuo Amasaka Shu Xu Hiroshi Hirata Hirotada Fujii Hirokazu Arimoto 《Tetrahedron letters》2014
A scalable synthetic route for 15N-labeled 4-oxo-2,2,6,6-tetraethylpiperidine nitroxide (15N-TEEPONE) is described. This 15N-labeled nitroxide is suitable for electron paramagnetic resonance imaging of brain, and its higher sensitivity compared with that of its 14N-counterpart is an important advantage of the labeled derivative. 相似文献
94.
Kawada Y Hirata H Fujii H 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,184(1):29-38
This article reports experimental investigations on the use of RF resonators for continuous-wave electron paramagnetic resonance (cw-EPR) and proton nuclear magnetic resonance (NMR) imaging. We developed a composite resonator system with multi-coil parallel-gap resonators for co-registration EPR/NMR imaging. The resonance frequencies of each resonator were 21.8MHz for NMR and 670MHz for EPR. A smaller resonator (22mm in diameter) for use in EPR was placed coaxially in a larger resonator (40mm in diameter) for use in NMR. RF magnetic fields in the composite resonator system were visualized by measuring a homogeneous 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (4-hydroxy-TEMPO) solution in a test tube. A phantom of five tubes containing distilled water and 4-hydroxy-TEMPO solution was also measured to demonstrate the potential usefulness of this composite resonator system in biomedical science. An image of unpaired electrons was obtained for 4-hydroxy-TEMPO in three tubes, and was successfully mapped on the proton image for five tubes. Technical problems in the implementation of a composite resonator system are discussed with regard to co-registration EPR/NMR imaging for animal experiments. 相似文献
95.
The vectorial Debye integral shows that tightly focused Laguerre-Gaussian (LG) beams have a residual intensity at the focal point for linear polarization, for a topological charge of m=1 and 2. We measured the shapes of linearly and circularly polarized LG beams and found that a central intensity appeared at m=1 and 2 for linear and right-handed circular polarization, however, it is completely canceled for left-handed circular polarization. In general, when the orbital angular momentum of the LG beam is parallel to the spin angular momentum of the photons, zero intensity is always achieved at the focus. 相似文献
96.
Dr. Yuki Kishimoto Dr. Osamu Nakagawa Akane Fujii Dr. Kotaro Yoshioka Dr. Tetsuya Nagata Prof. Dr. Takanori Yokota Prof. Dr. Yoshiyuki Hari Prof. Dr. Satoshi Obika 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2427-2438
Artificial nucleic acids are widely used in various technologies, such as nucleic acid therapeutics and DNA nanotechnologies requiring excellent duplex-forming abilities and enhanced nuclease resistance. 2′-O,4′-C-Methylene-bridged nucleic acid/locked nucleic acid (2′,4′-BNA/LNA) with 1,3-diaza-2-oxophenoxazine (BNAP ( BH )) was previously reported. Herein, a novel BH analogue, 2′,4′-BNA/LNA with 9-(2-aminoethoxy)-1,3-diaza-2-oxophenoxazine (G-clamp), named BNAP-AEO ( BAEO ), was designed. The BAEO nucleoside was successfully synthesized and incorporated into oligodeoxynucleotides (ODNs). ODNs containing BAEO possessed up to 104-, 152-, and 11-fold higher binding affinities for complementary (c) RNA than those of ODNs containing 2′-deoxycytidine ( C ), 2′,4′-BNA/LNA with 5-methylcytosine ( L ), or 2′-deoxyribonucleoside with G-clamp ( PAEO ), respectively. Moreover, duplexes formed by ODN bearing BAEO with cDNA and cRNA were thermally stable, even under molecular crowding conditions induced by the addition of polyethylene glycol. Furthermore, ODN bearing BAEO was more resistant to 3′-exonuclease than ODNs with phosphorothioate linkages. 相似文献
97.
Hüseyin Aksel Eren Ozan Avinc Burcu Erişmiş Semiha Eren 《Cellulose (London, England)》2014,21(6):4643-4658
In this study, the effects of ultrasound on ozone treatment processes for bleaching cotton fabrics were investigated and compared with the conventional hydrogen peroxide bleaching process (60 °C over 90 min). Two ultrasonic + ozone treatments of cotton fabric samples were carried out: (1) ozone in an ultrasonic homogenizer (UH) and (2) ozone in an ultrasonic bath. Ozone dosages, temperature and time variations were determined with both ozone-ultrasonic bleaching processes. Whiteness, yellowness, weight, tensile strength properties, FTIR (ATR) spectra and visual appearance, via scanning electron microscopy of treated cotton fabrics as well as chemical oxygen demand (COD) of bleaching effluents, were investigated. It was concluded that the ozone + UH process, conducted for 30 min at 30 °C, produced closely equivalent values of cotton fabric whiteness and yellowness to the classic peroxide bleaching process, with slightly less weight loss, dramatically less COD in the process effluent (29 mg/l for ozone-UH vs. 4,316 mg/l for classical peroxide treatment), and without causing any adverse and/or detrimental effects on loss of fabric strength or elongation of the cotton fabrics. The ozone-UH process also leads to time and energy savings with much less environmental impact. Consequently, the combination of ozonation plus UH carried out at 30 °C over 30 min can be used successfully for cotton bleaching instead of the classic hydrogen peroxide bleaching process. 相似文献
98.
Syuji Fujii Yuma Yamashita Yoshinobu Nakamura Akira Tsuchida Tsuneo Okubo 《Colloid and polymer science》2014,292(7):1627-1637
Colloidal crystallization and amorphous solidification of deionized suspensions of the polydispersed cationic gel spheres of lightly cross-linked poly(2-vinylpyridine), CAIBA-P2VP (107~113 nm in diameter, ±19~22 nm in dispersity), have been studied from the reflection spectroscopy, morphology, phase diagram, and elastic property. Crystallization takes place even for the polydispersed cationic gel spheres by the significant contribution of the extended electrical double layers formed around the spheres. Critical concentrations of melting coexisted with ion exchange resins were around 0.02 in volume fraction and high compared with those of other cationic and anionic gel crystals examined hitherto. The densities (ρ) of CAIBA-P2VP in suspension state, i.e., weight percent of the gel spheres divided by the corresponding volume percent, was around 0.3. The ρ values decreased sharply with decreasing size of P2VP gel spheres, which supports the small gel spheres containing much water inside and being softer than the large ones. The closest intersphere distances of the crystals and/or amorphous solids were much longer than the hydrodynamic diameters of the gel spheres especially at low sphere concentrations. Fluctuation parameters (b) evaluated from the rigidities of CAIBA-P2VP (0.15~0.28) were large compared with those of gel crystals of large-sized P2VP-based cationic gel spheres, anionic thermosensitive gel spheres of poly(N-isopropylacrylamide) (0.05~0.09) and further much larger than those of typical colloidal hard spheres (around 0.03). The dispersity in sphere size played an important role for distinguishing crystal and amorphous solid. Importance of the extended electrical double layers around the cationic gel spheres is supported in addition to the excluded volume effect of the sphere themselves on the crystallization and/or solidification. 相似文献
99.
Yuki Kataoka Dr. Naoya Kanbayashi Naoka Fujii Dr. Taka-aki Okamura Prof. Takeharu Haino Prof. Kiyotaka Onitsuka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10372-10377
π-Stacked polymers, which consist of layered π-electron systems in a polymer, can be expected to be used in molecular electronic devices. However, the construction of a stable π-stacked structure in a polymer is considerably challenging because it requires sophisticated designs and precise synthetic methods. Herein, we present a novel π-stacked architecture based on poly(quinolylene-2,3-methylene) bearing alanine derivatives as the side chain, obtained through the living cyclo-copolymerization of an o-allenylaryl isocyanide. In the resulting polymer, the neighboring quinoline rings of the main chain form a layered structure with π–π interactions, which is stabilized by intramolecular hydrogen bonds. The vicinal quinoline units form two independent helices and the whole molecule is a twisted-tape structure. This structure is established on the basis of UV/CD spectra, theoretical calculations, and atomic-force microscopy. 相似文献
100.
Yuki Kataoka Naoya Kanbayashi Naoka Fujii Taka‐aki Okamura Takeharu Haino Kiyotaka Onitsuka 《Angewandte Chemie (International ed. in English)》2020,59(26):10286-10291
π‐Stacked polymers, which consist of layered π‐electron systems in a polymer, can be expected to be used in molecular electronic devices. However, the construction of a stable π‐stacked structure in a polymer is considerably challenging because it requires sophisticated designs and precise synthetic methods. Herein, we present a novel π‐stacked architecture based on poly(quinolylene‐2,3‐methylene) bearing alanine derivatives as the side chain, obtained through the living cyclo‐copolymerization of an o‐allenylaryl isocyanide. In the resulting polymer, the neighboring quinoline rings of the main chain form a layered structure with π–π interactions, which is stabilized by intramolecular hydrogen bonds. The vicinal quinoline units form two independent helices and the whole molecule is a twisted‐tape structure. This structure is established on the basis of UV/CD spectra, theoretical calculations, and atomic‐force microscopy. 相似文献