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971.
Shiga T Miyasaka H Yamashita M Morimoto M Irie M 《Dalton transactions (Cambridge, England : 2003)》2011,40(10):2275-2282
Two assemblies composed of single-molecule magnets (SMMs) linked by photochromic ligands, [Cu(II)(2)Tb(III)(2)(L)(2)(NO(3))(2)(dae-o)(2)]·2(n-BuOH) (1) and {[Cu(II)Tb(III)(L)(n-BuOH)(0.5)](2)(dae-c)(3)}·5(DMF)·4(n-BuOH)·2(H(2)O) (2), were synthesized by reacting the SMM [Cu(II)Tb(III)(L)(NO(3))(3)] (H(2)L = 1,3-bis((3-methoxysalicylidene)amino)propane) and photochromic molecules, H(2)dae-o and H(2)dae-c, which are open- and closed-ring isomers of 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluoropentene (H(2)dae), respectively. 1 has a tetranuclear ring-like structure comprised of two [CuTb] units and two dae-o(2-) ligands. On the other hand, 2 has a one-dimensional ladder-type structure involving the [CuTb] and dae-c(2-) units in a 3?:?2 ratio. Magnetic studies revealed that 1 and 2 had ferromagnetic interactions between the Cu(II) and Tb(III) ions and that both compounds exhibited frequency dependence of ac susceptibilities owing to freezing the magnetization of the [CuTb] SMM. Upon irradiation with ultraviolet light and visible light, an absorption band at ~600 nm changed, indicating that photochromic reactions involving the dae(2-) ligands occurred. After irradiation, the magnetic behaviour of 1 did not change, whereas magnetic behaviour of 2 changed, due to the modification of intermolecular environment. 相似文献
972.
Yamashita F Feng C Yoshida S Itoh T Hashida M 《Journal of chemical information and modeling》2011,51(2):378-385
Information on CYP-chemical interactions was comprehensively explored by a text-mining technique, to confirm our previous structure-activity relationship model for CYP substrates (Yamashita et al. J. Chem. Inf. Model. 2008, 48, 364-369). The text-mining technique is based on natural language processing and can extract chemical names and their interaction patterns according to sentence context. After chemicals were automatically extracted and classified into CYP substrates, inhibitors, and inducers, 709 substrates were retrieved from the PubChem database and categorized as 216, 145, 136, 217, 156, and 379 substrates for CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4, respectively. Although the previous classification model was developed using data from only 161 compounds, the model classified the substrates found by text-mining analysis with reasonable accuracy. This confirmed the validity of both the multi-objective classification model for CYP substrates and the text-mining procedure. 相似文献
973.
Norihisa Fukaya Hiroshi Yamashita Teruhisa Tsuchimoto Toshiyasu Sakakura 《Journal of organometallic chemistry》2011,696(4):825-5027
Microwave (MW)-assisted (2.45 GHz) organic functionalization of silica surfaces was investigated using (3-chloropropyl)dimethylsilanes with alkoxy, allyl, or aryl leaving groups in heptane or toluene at 80 °C. 29Si and 13C CP/MAS spectroscopy confirmed the 3-chloropropyldimethylsilyl moiety was covalently grafted onto silica for all the samples. The effect of MW irradiation on the loading amount strongly depended on the leaving group as well as the solvent; using methoxysilane and p-anisylsilane in heptane caused a distinct acceleration. The correlation with the dielectric loss factors of the silylating agents suggested that the MW acceleration effect resulted from selectively heating the strongly MW-absorbing silylating agent. For the grafting reaction in toluene, the MW effect was not observed possibly because toluene masked the selective heating effect of the silylating agent. 相似文献
974.
Yamashita K Nagashima Y Yamamoto Y Nishiyama H 《Chemical communications (Cambridge, England)》2011,47(41):11552-11554
The first transfer-hydrogenative cyclization of 1,6-diynes that leads to exocyclic dienes was developed using a ruthenium catalyst and MeOH as a H(2) surrogate. 相似文献
975.
Mitsuki Hoshi Ryuhei Nishiyabu Yuichiro Hayashi Shigeyuki Yagi Yuji Kubo 《化学:亚洲杂志》2020,15(6):787-795
We found that boronate particles ( BP ), as a self‐assembled system prepared by sequential dehydration of benzene‐1,4‐diboronic acid with pentaerythritol, showed greenish room‐temperature phosphorescence (RTP). This emission was observed in both solid and dispersion state in water. To understand the RTP properties, X‐ray crystallographic analysis, and density functional theory (DFT) and time‐dependent DFT at M06‐2X/6‐31G(d,p) level were performed using 3,9‐dibenzo‐2,4,8,10‐tetraoxa‐3,9‐diboraspiro[5.5]undecane ( 1 ) as a model compound. Our interest in functionalizing the RTP‐active particles led us to graft Rhodamine B onto their surface. The resulting system emitted a dual afterglow via a Förster‐type resonance energy transfer process from the BP in the excited triplet state to Rhodamine B acting as an acceptor fluorophore. This emission behavior was used for ratiometric afterglow sensing of water content in THF with a detection limit of 0.28 %, indicating that this study could pave the way for a new strategy for developing color‐variable afterglow chemosensors for various analytes. 相似文献
976.
Yu Yamashita Ekaterina V. Vinogradova Xiaoyu Zhang Radu M. Suciu Benjamin F. Cravatt 《Angewandte Chemie (International ed. in English)》2020,59(10):3896-3899
Target engagement assays are crucial for establishing the mechanism‐of‐action of small molecules in living systems. Integral membrane transporters can present a challenging protein class for assessing cellular engagement by small molecules. The chemical proteomic discovery of alpha‐chloroacetamide (αCA) compounds that covalently modify cysteine‐54 (C54) of the MPC2 subunit of the mitochondrial pyruvate carrier (MPC) is presented. This finding is used to create an alkyne‐modified αCA, YY4‐yne, that serves as a cellular engagement probe for MPC2 in click chemistry‐enabled western blotting or global mass spectrometry‐based proteomic experiments. Studies with YY4‐yne revealed that UK‐5099, an alpha‐cyanocinnamate inhibitor of the MPC complex, engages MPC2 with remarkable selectivity in human cells. These findings support a model where UK‐5099 inhibits the MPC complex by binding to C54 of MPC2 in a covalent reversible manner that can be quantified in cells using the YY4‐yne probe. 相似文献
977.
Syntheses and Structure of Hexacoordinated Selenium (λ6-Selane) and Tellurium (λ6-Tellane) Compounds
Soichi Sato Takeshi Ueminami Takahiro Yamashita Hiroshi Arakawa Ernst Horn Ohgi Takahashi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):595-598
The first isolation of bis(2,2′-biphenylylene)dichloro- and difluoro-perchalcogenuranes, [12–Se–6(C4F2)] (λ6-selane); [12–Te–6(C4X2), X = Cl, F] (λ6-tellane) and the corresponding tellurane Te-oxide dimer [12–Te–6(C4O2)]2, and their crystal and molecular structures are described. Furthermore, on the basis of the difference between the 3c-4e bonds of the dodecet species and that of the decet species a new molecular orbital concept has been proposed on the 3c-4e bond of perchalcogenurane species [12–M–6, M = chalcogen atoms]. 相似文献
978.
Eiichi Ozu Natsuki Yamashita Hiroshi Inoue Toshihisa Maeshima Ion C. Baianu Lun Shin Wei 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1525-1538
In the anionic polymerization of methyl methacrylate (MMA) induced by imidazole (Im), an Im‐MMA adduct forms as an initiator adduct in methanol at 30°C in an argon atmosphere by the equimolar reaction of Im with the MMA monomer. The additive effect of the adduct on the homopolymerization of MMA in tetrahydrofuran at 30°C was investigated by dilatometry. The existence of the adduct increased the duration of the propagation step without shortening the formation step of the initiator adduct. The H‐D exchange reaction of the adduct was observed in D2O by 1H NMR. Proton transfer of the MMA unit in the adduct was not observable until 45 h after initiation. The copolymerizability of MMA with acrylamide (AAm) induced by the Im catalyst in THF at 30°C was also investigated. It was found that the homo‐and copolymerizations proceeded at the same time. On the other hand, in the MMA homopolymerization system, the addition of AAm monomer during the initial propagation step yielded copolymer of MMA and AAm for near equimolar concentration of the charged monomers. 相似文献
979.
Natsuki Yamashita Hiroyuki Tanaka Satoru Deguchi Toshihisa Maeshima Lun-Shin Wei 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1121-1134
The kinetics of the polymerization of methyl methacrylate (MMA) in the presence of imidazole (Im), 2-methylimidazole (2MIm), or benz-imidazole (BIm) in tetrahydrofuran (THF) at 15–40°C was investigated by dilatometry. The rate of polymerization, Rp , was expressed by Rp = k[Im] [MMA]2, where k = 3.0 × 10?6 L2/(mol2 s) in THF at 30°C. The overall activation energy, Ea , was 6.9 kcal/mol for the Im system and 7.3 kcal/mol for the 2MIm system. The relation between logRp and 1 T was not linear for the BIm system. The polymers obtained were soluble in acetone, chloroform, benzene, and THF. The melting points of the polymers were in the range of 258–280°C. The 1H-NMR spectra indicated that the polymers were made up of about 58–72% of syndiotactic structure. The polymerization mechanism is discussed on the basis of these results. 相似文献
980.
Satoshi Morita Hiroshi Inoue Natsuki Yamashita Toshihisa Maeshima 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):1003-1015
Polymerizabilities of several polar vinyl monomers in the presence of imidazole (Im) have been studied in CDC13 and CD3OD by NMR spectra. Acrylic acid formed a bimolecular adduct with Im as the initial adduct, while methacrylic acid was not obtained, On the other hand, methyl acrylate, methyl methacrylate (MMA), acrylamide (AAm), and acrylonitrile formed the initial adduct between Im and monomer, respectively. In these monomers, AAm and MMA gave each polymer in tetrahydrofuranat room temperature. The number-average molecular weight ([Mbar]n) of AAm polymers was determined to be in the range of 1000 to 1500, and the [Mbar]n of MMA polymers was found to be in the range of 2500 to 4500, The rate of polymerization Rp was expressed by the equations Rp = k[Im][AAm] and Rp = k[Im] [MMA]2, respectively. The activation energy ER was obtained by Arrheniuss's plots as ER(AAm) = 9.6 kcal/mol and ER(MMA) = 3.8 kcal/mol. These polymerization mechanisms are discussed on the basis of these results. 相似文献