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21.
The conductance through single 7,7,8,8‐tetracyanoquinodimethane (TCNQ) connected to gold electrodes is studied with the nonequilibrium Green’s function method combined with density functional theory. The aim of the study is to derive the effect of a dicyano anchor group, ?C(CN)2, on energy level alignment between the electrode Fermi level and a molecular energy level. The strong electron‐withdrawing nature of the dicyano anchor group lowers the LUMO level of TCNQ, resulting in an extremely small energy barrier for electron injection. At zero bias, electron transfer from electrodes easily occurs and, as a consequence, the anion radical state of TCNQ with a magnetic moment is formed. The unpaired electron in the TCNQ anion radical causes an exchange splitting between the spin‐α and spin‐β transmission spectra, allowing the single TCNQ junction to act as a spin‐filtering device. 相似文献
22.
Prof. Dr. Michio Yamada Yuta Uokawa Shino Sasaki Naohiro Iha Yoshihisa Hashimoto Yuya Nagasaki Prof. Dr. Yutaka Maeda Prof. Dr. Mitsuaki Suzuki 《European journal of organic chemistry》2023,26(35):e202300633
The physicochemical properties of fullerene-based materials typically vary depending on the type and mode of addition of functional groups; therefore, developing fullerene derivatives with novel structures is imperative for further progress in materials science. In this study, we develop an efficient one-step strategy for synthesizing cyclobutene-annulated fullerene derivatives (cyclobutenofullerenes) and characterize their electronic properties. Despite the steric strain, cyclobutenofullerenes can be easily prepared via a one-step reaction of C60 with a secondary propargylic phosphate. Structural analysis of the reaction intermediates suggests that the cascade reaction proceeds through a formal [2+2] cycloaddition of C60 with an allene, caused by the 1,3-migration of the propargylic phosphate, followed by an additional 1,3-migration and the subsequent 1,2-elimination of the phosphodiester moiety. 相似文献
23.
Polymerization of optically active disubstituted acetylene monomers by Pd catalyst bearing bulky phosphine ligand 下载免费PDF全文
Yuta Goto Yu Miyagi Natsuhiro Sano Fumio Sanda 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):3011-3016
Chloro- and aryl-substituted acetylene monomers having an optically active group were polymerized by a Pd catalyst [(tBu3P)PdMeCl] bearing a bulky phosphine ligand, and by MoCl5 for comparison. The corresponding disubstituted acetylene polymers with Mn's = 2000–19,500 and 6900–10,800 were obtained in 29–83% and 11–62% yields when the Pd and Mo catalysts were used, respectively. The formation of polyacetylenes, poly[(R)- 1p ], poly[(R)- 1m ], and poly[(S)- 2p ] were confirmed by SEC and the presence of a Raman scattering peak based on the alternating double bonds of the main chain. Pd-based poly[(R)- 1m ] exhibited CD signals around 350 nm assignable to a certain secondary structure, while Mo-based poly[(R)- 1m ] did not. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3011–3016 相似文献
24.
Prof. Dr. Yasuchika Hasegawa Takafumi Matsui Dr. Yuichi Kitagawa Dr. Takayuki Nakanishi Dr. Tomohiro Seki Prof. Dr. Hajime Ito Prof. Dr. Yuta Nakasaka Prof. Dr. Takao Masuda Prof. Dr. Koji Fushimi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12308-12315
Oxygen-sensitive and near-infrared (NIR) luminescent YbIII coordination polymers incorporating ligands based on pyrene derivatives were synthesized: YbIII–TBAPy and YbIII–TIAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoate)pyrene; TIAPy: 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene). The coordination structures of these materials have been characterized by means of electrospray ionization mass spectrometry, X-ray diffraction analysis, and thermogravimetric analysis. Moreover, the porous structure of YbIII–TIAPy has been evaluated by measuring its N2 adsorption isotherm. The NIR luminescence properties of YbIII–TBAPy and YbIII–TIAPy have been examined by acquiring emission spectra and determining emission lifetimes under air or argon and in vacuo. YbIII–TIAPy exhibited high thermal stability (with a decomposition temperature of 400 °C), intense luminescence (with an emission quantum yield under argon of 6.6 %), and effective oxygen-sensing characteristics. These results suggest that NIR luminescent YbIII coordination polymers prepared using pyrene derivatives could have applications in novel thermo-stable oxygen sensors. 相似文献
25.
The stability constants (β1) of the monofluoro complex of Sm(III) have been determined in mixed solvents of methanol and water at a 0.10 mol·dm−3 ionic strength using the solvent extraction technique. The values of lnβ1 increase as the mole fraction of methanol (X
s) in the mixed solvent system increases. The variation in the stability constants can be correlated with both the large effect
due to the solvation of F− and the small effect due to both (1) the solvation of cations in connection with the complexation of SmF2+ and (2) the electrostatic attraction of Sm3+−F−. Based on the variation in the sum of (1) and (2) in H2O and the mixed solvent solutions, it was determined that the coordination number (CN) of Sm(III) varied from a mixture of
CN=9 and 8 to CN=8 for about a 0.06 mole fraction of methanol (X
s) in the mixed solvent. TheX
s value of the inflection point of the CN for Sm(III) is slightly higher thanX
s=0.03 for Eu(III) previously determined by us. 相似文献
26.
Kumagai Yuta Kimura Atsushi Taguchi Mitsumasa Watanabe Masayuki 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):341-348
Journal of Radioanalytical and Nuclear Chemistry - This study aims to demonstrate that zeolite has the potential to increase the efficiency of radiolysis treatment of aqueous organic pollutants by... 相似文献
27.
Izumi Sakamoto Kazuya Iwaoka Yuta Kawada Takanori Naito Kazuyoshi Makida Yuki Takeuchi Takeshi Nishii Mitsuyo Horikawa Hiroto Kaku Tetsuto Tsunoda 《Tetrahedron》2018,74(24):3052-3060
3,3-Dimethoxypropylsulfonyl (Dimps) chloride was prepared and used as a new versatile sulfonating agent for ammonia, primary and secondary amines to afford corresponding Dimps-amides in excellent yields. The resulting N-nonsubstituted and N-monosubstituted Dimps-amides, activated amines, were alkylated satisfactorily under new Mitsunobu conditions. The Dimps group was removed by treatment in aqueous solution under acidic followed by basic conditions. Furthermore, epilachnene, the defensive droplets from the Mexican bean beetle, Epilachna varivestis, was synthesized utilizing this Dimps methodology in short steps. 相似文献
28.
Yuta Hirosawa Hiroaki Imoto Kensuke Naka 《Journal of polymer science. Part A, Polymer chemistry》2024,62(3):564-571
Cage silsesquioxanes, also known as polyhedral oligomeric silsesquioxanes (POSS), serve as crucial building blocks in crafting precisely designed organic–inorganic hybrid materials, given that their well-defined silsesquioxane clusters can be adorned with organic substituents. While polymers with POSS in their main chains have been thoroughly examined, analyzing the correlation between cage structure and material properties in main-chain-type polymers remains challenging. This difficulty stems from the limited range of organic substituents on traditional POSS monomers, thereby precluding comparisons between polymers with unified substituents and different cage structures. In this study, we synthesized double-decker silsesquioxane (DDSQ) and side-opened POSS (SO-POSS) monomers, both featuring phenyl groups. Subsequent platinum-catalyzed hydrosilylation polymerization yielded main-chain-polymers. Both the cage and linker structures influence thermal stability and the glass transition temperature, while the hardness was primarily determined by the linker structure. This research is the first to elucidate the impact of cage structure on the material properties of main-chain-type POSS polymers. 相似文献
29.
We will focus on estimating the integrated covariance of two diffusion processes observed in a nonsynchronous manner. The observation data is contaminated by some noise, which possibly depends on the time and the latent diffusion processes, while the sampling times also possibly depend on the observed processes. In a high-frequency setting, we consider a modified version of the pre-averaged Hayashi–Yoshida estimator, and we show that such a kind of estimator has the consistency and the asymptotic mixed normality, and attains the optimal rate of convergence. 相似文献
30.
Planning a cost‐efficient monitoring policy of stochastic processes arises from many industrial problems. We formulate a simple discrete‐time monitoring problem of continuous‐time stochastic processes with its applications to several industrial problems. A key in our model is a doubling trick of the variables, with which we can construct an algorithm to solve the problem. The cost‐efficient monitoring policy balancing between the observation cost and information loss is governed by an optimality equation of a fixed point type, which is solvable with an iterative algorithm based on the Feynman‐Kac formula. This is a new linkage between monitoring problems and mathematical sciences. We show regularity results of the optimization problem and present a numerical algorithm for its approximation. A problem having model ambiguity is presented as well. The presented model is applied to problems of environment, ecology, and energy, having qualitatively different target stochastic processes with each other. 相似文献