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991.
A Doubly Alkynylpyrene‐Threaded [4]Rotaxane That Exhibits Strong Circularly Polarized Luminescence from the Spatially Restricted Excimer
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Prof. Dr. Masahiko Inouye Koichiro Hayashi Yuki Yonenaga Dr. Tatsuya Itou Dr. Kazuhisa Fujimoto Taka‐aki Uchida Dr. Munetaka Iwamura Prof. Dr. Koichi Nozaki 《Angewandte Chemie (International ed. in English)》2014,53(52):14392-14396
The Sonogashira coupling of γ‐CD‐encapsulated alkynylpyrenes with terphenyl‐type stopper molecules gave a doubly alkynylpyrene‐threaded [4]rotaxane. The rotaxane showed only excimer emission, with a high fluorescence quantum yield of Φf=0.37, arising from the spatially restricted excimer within the cavity of the γ‐CD. The excimer emission suffered little from self‐quenching up to a concentration of 1.5×10?5 M and was circularly polarized with a high glum value of ?1.5×10?2. The strong circularly polarized luminescence may result from the two stacked pyrenes existing in the rotaxane in an asymmetrically twisted manner. 相似文献
992.
Influence of Charging Current and Potential Drop on the Propagation of the Change in the Membrane Potential
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Propagation of a change in a potential difference between two aqueous phases (W1 and W2) across a membrane was examined by using three membrane cells (A, B and C). At first, the cell A was electrically connected with the cell B by controlling the ionic compositions. By changing the connection with the cell A from the cell B to the cell C indicating the different membrane potential, the change of the membrane potential was propagated. The delay and decrement of the propagation was observed by setting capacitors or resistors in the electric circuit. 相似文献
993.
Color‐Discriminating Retinal Configurations of Sensory Rhodopsin I by Photo‐Irradiation Solid‐State NMR Spectroscopy
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Hiroki Yomoda Yoshiteru Makino Yuya Tomonaga Tetsurou Hidaka Dr. Izuru Kawamura Dr. Takashi Okitsu Prof. Akimori Wada Dr. Yuki Sudo Prof. Akira Naito 《Angewandte Chemie (International ed. in English)》2014,53(27):6960-6964
SRI (sensory rhodopsin I) can discriminate multiple colors for the attractant and repellent phototaxis. Studies aimed at revealing the color‐dependent mechanism show that SRI is a challenging system not only in photobiology but also in photochemistry. During the photoreaction of SRI, an M‐intermediate (attractant) transforms into a P‐intermediate (repellent) by absorbing blue light. Consequently, SRI then cycles back to the G‐state. The photoreactions were monitored with the 13C NMR signals of [20‐13C]retnal‐SrSRI using in situ photo‐irradiation solid‐state NMR spectroscopy. The M‐intermediate was trapped at ?40 °C by illumination at 520 nm. It was transformed into the P‐intermediate by subsequent illumination at 365 nm. These results reveal that the G‐state could be directly transformed to the P‐intermediate by illumination at 365 nm. Thus, the stationary trapped M‐ and P‐intermediates are responsible for positive and negative phototaxis, respectively. 相似文献
994.
One‐Pot Halogen Dance/Negishi Coupling of Dibromothiophenes for Regiocontrolled Synthesis of Multiply Arylated Thiophenes
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Prof. Dr. Kentaro Okano Kazuhiro Sunahara Yoshiki Yamane Yuki Hayashi Prof. Dr. Atsunori Mori 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16450-16454
One‐pot halogen dance/Negishi cross‐coupling of readily available 2,5‐dibromothiophenes is described. A lithium diisopropylamide (LDA)‐mediated halogen dance reaction resulted in the formation of thermodynamically stable α‐lithiodibromothiophenes, which were transmetalated with ZnCl2 and subjected to Negishi cross‐coupling to provide the corresponding arylated dibromothiophenes in one pot. The resultant β‐bromo group was much less reactive than the remaining α‐bromo group, which was used in a one‐pot double Suzuki–Miyaura cross‐coupling, enabling facile synthesis of multiply arylated thiophenes. 相似文献
995.
Yuki Hirai Hitoshi Tamiaki Shigenori Kashimura Yoshitaka Saga 《Photochemistry and photobiology》2009,85(5):1140-1146
Demetalation kinetics of bacteriochlorophylls (BChls) c, d and e from green sulfur photosynthetic bacteria were studied under weakly acidic conditions. Demetalation rate constants of BChl e possessing a formyl group at the 7-position were significantly smaller than those of BChls c and d , which had a methyl group at this position. The activation energy of demetalation of 31 R -8,12-diethyl([E,E])-BChl e was 1.5-times larger than that of 31 R -[E,E]-BChl c . 15 N-labeled 31 R -[E,E]-BChls c and e were purified from cells of green sulfur bacteria grown in a medium containing 15 NH4 Cl, and their 15 N NMR spectra were measured. The chemical shifts of N21 , N22 and N23 atoms of 31 R -[E,E]-BChl e were lower-field shifted than those of 31 R -[E,E]-BChl c , respectively, and especially the difference in chemical shifts of N22 was significantly large. These results suggest that the electron-withdrawing formyl group at the 7-position of BChl e affected an electronic state of the chlorin macrocycle and caused BChl e to be more tolerant for removal of the central magnesium compared with BChls c and d . 相似文献
996.
Ryoichi Hirayama Yoshitaka Matsumoto Yuki Kase Miho Noguchi Koichi Ando Atsushi Ito Ryuichi Okayasu Yoshiya Furusawa 《Radiation Physics and Chemistry》2009,78(12):1175-1178
The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/μm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52±9%. We conclude that OH radical-mediated indirect action still has a half in total contribution on cell killing under hypoxic condition. 相似文献
997.
Yuko Okuyama Yuki Watanabe Mitsuhiro Takeshita Eunsang Kwon 《Tetrahedron letters》2009,50(2):193-5137
4-Hydroxy-prolinamide alcohol with different noncoordination sites as a molecule showed excellent asymmetric catalytic activity in both the Michael reaction (up to 98% ee) and the direct aldol reaction (up to >99% ee), and the catalyzing reactions with high enantioselectivity are supported by a DFT theoretical study of their transition state. 相似文献
998.
999.
We show that if a class K of finite relational structures is closed under quasi‐substructures, then there is no saturated K ‐generic structure that is superstable but not ω ‐stable (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
1000.