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101.
Isolation and Structure Determination of a Missing Endohedral Fullerene La@C70 through In Situ Trifluoromethylation 下载免费PDF全文
Dr. Zhiyong Wang Prof. Dr. Shinobu Aoyagi Dr. Haruka Omachi Prof. Dr. Ryo Kitaura Prof. Dr. Hisanori Shinohara 《Angewandte Chemie (International ed. in English)》2016,55(1):199-202
D5h‐symmetric fullerene C70 (D5h‐C70) is one of the most abundant members of the fullerene family. One longstanding mystery in the field of fullerene chemistry is whether D5h‐C70 is capable of accommodating a rare‐earth metal atom to form an endohedral metallofullerene M@D5h‐C70, which would be expected to show novel electronic properties. The molecular structure of La@C70 remains unresolved since its discovery three decades ago because of its extremely high instability under ambient conditions and insolubility in organic solvents. Herein, we report the single‐crystal X‐ray structure of La@C70(CF3)3, which was obtained through in situ exohedral functionalization by means of trifluoromethylation. The X‐ray crystallographic study reveals that La@C70(CF3)3 is the first example of an endohedral rare‐earth fullerene based on D5h‐C70. The dramatically enhanced stability of La@C70(CF3)3 compared to La@C70 can be ascribed to trifluoromethylation‐induced bandgap enlargement. 相似文献
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Matsuda H Hamao M Nakamura S Kon'i H Murata M Yoshikawa M 《Chemical & pharmaceutical bulletin》2012,60(5):674-680
Effects of principal saponins, chakasaponins I-III, from the flower buds of Camellia sinensis cultivated in Fujian province, China on plasma triglyceride (TG) and glucose levels in olive oil or sucrose-loaded mice were examined. Chakasaponins I-III at 50 and 100 mg/kg significantly inhibited increases in plasma TG and glucose levels. Furthermore, they prevented gastric emptying, suggesting that the former inhibitory effect is partly dependent on the inhibition of gastric emptying. In addition, the chemical structure of a new acylated oleanane-type triterpene oligoglycoside, chakasaponin IV, was elucidated on the basis of chemical and physicochemical evidence. 相似文献
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Yoshimura K Muramatsu J Davis P Harayama T Okumura H Morikatsu S Aida H Uchida A 《Physical review letters》2012,108(7):070602
We propose a secure key distribution scheme based on correlated physical randomness in remote optical scramblers driven by common random light. The security of the scheme depends on the practical difficulty of completely observing random optical phenomena. We describe a particular realization using the synchronization of semiconductor lasers injected with common light of randomly varying phase. We experimentally demonstrate the feasibility of the scheme over a distance of 120 km. 相似文献
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Kazunori Nozaki Masanori Nakamura Haruka Takimoto Shigeo Wada 《Journal of computational science》2012,3(5):298-305
Sibilant /s/, which is an unvoiced sound, is believed to be produced by a jet of air through a sibilant groove toward the sharp edges of the teeth. We investigated what effects the expiratory flow rate had on the acoustic characteristics of sibilant /s/ in the present study. A large eddy simulation was implemented to investigate the flow in an oral cavity model that simplified the important anatomical features of the oral cavity when sibilant /s/ was pronounced. The results illustrated that an increase in the expiratory flow rate caused turbulence to develop in the separated flow from the edge of the obstacle wall which mimics a tooth. The increase in turbulent intensity induced a dramatic elevation in Lamb-vector divergence in the flow-separation region, which was regarded as a sound source of sibilant /s/. The total power of the sound source which was located near the obstacle edge of the obstacle wall at smaller flow rates, extended downstream in the flow separation as the expiratory flow rate increased through which turbulence developed. These results demonstrated that the expiratory flow rate had a significant influence on the acoustic characteristics of sibilant /s/ particularly when the flow rate increased to cause turbulence. 相似文献
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We study the effects of fluctuations of cross-linking points, or junctions, on the dynamic mechanical and viscoelastic properties of polymer networks formed by multisticker associating polymers on the basis of a single-chain approach. Fluctuations of junctions are implemented by introducing virtual springs. We consider two possible cases for the treatment of virtual springs: the direct contribution from virtual springs is either neglected or included in the stress. We show that, if neglected, the fluctuation of junctions decreases (or softens) the dynamic modulus over a wide range of frequencies. This result agrees qualitatively with the result of several multichain models that predicts the decrease of the static or plateau modulus. We also show that the fluctuation accelerates the associative Rouse mode at low frequencies originating from the association/dissociation process of stickers. These results are apparently reasonable, but it is expected that there are some errors arising from thermodynamical inconsistency due to the neglect of virtual-spring contribution from the total stress against the virtual work principle and the second law of thermodynamics. On the other hand, if the direct contribution from the virtual springs is included in the stress, thermodynamics is satisfied but the plateau modulus does not change, contrary to the multichain prediction. The softening occurs only at the low-frequency regime. Thus, each method has both merits and demerits, and hence the treatment of junction fluctuations in the framework of single-chain approaches requires care and further investigation. 相似文献
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Bungo Ochiai Haruka Amemiya Hiroki Yamazaki Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):2802-2808
Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate‐urethane). The hydrolysis and thermal behaviors of poly(HC‐MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND‐MDI)) prepared from MDI and 1,9‐nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC‐MDI) is less crystalline than poly(ND‐MDI). Poly(HC‐MDI) is more susceptible to hydrolysis than poly(ND‐MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802–2808, 2006 相似文献
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