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101.
Synergistic Spin Transition between Spin Crossover and Spin‐Peierls‐like Singlet Formation in the Halogen‐Bonded Molecular Hybrid System: [Fe(Iqsal)2][Ni(dmit)2]⋅CH3CN⋅H2O 下载免费PDF全文
Kappei Fukuroi Prof. Dr. Kazuyuki Takahashi Prof. Dr. Tomoyuki Mochida Dr. Takahiro Sakurai Prof. Dr. Hitoshi Ohta Dr. Takashi Yamamoto Prof. Dr. Yasuaki Einaga Prof. Dr. Hatsumi Mori 《Angewandte Chemie (International ed. in English)》2014,53(7):1983-1986
To introduce halogen‐bond interactions between a cation and an anion, a novel FeIII complex from iodine‐substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin‐crossover transition and a spin‐Peierls‐like singlet formation. The halogen‐bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of π‐spins and played a crucial role in the synergistic magnetic transition between d‐ and π‐spins. In addition, the compound showed the light‐induced excited spin state trapping effect. 相似文献
102.
Kenji Shirokane Takamasa Wada Makoto Yoritate Ryo Minamikawa Nobuaki Takayama Dr. Takaaki Sato Prof. Dr. Noritaka Chida 《Angewandte Chemie (International ed. in English)》2014,53(2):512-516
A chemoselective approach for the total synthesis of (±)‐gephyrotoxin has been developed. The key to success was the utilization of N‐methoxyamides, which enabled the direct coupling of the amide with an aldehyde and selective reductive nucleophilic addition to the amide in the presence of a variety of sensitive and electrophilic functional groups, such as a methyl ester. This chemoselective approach minimized the use of protecting‐group manipulations and redox reactions, which resulted in the most concise and efficient total synthesis of (±)‐gephyrotoxin described to date. 相似文献
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Nobuaki Kitazawa Dhebbajaji Yaemponga Masami Aono Yoshihisa Watanabe 《Journal of luminescence》2009,129(9):1036-1041
Thin films of microcrystalline (C8H17NH3)2PbBr4 have been prepared by the two-step growth process as follows: (1) precipitation of nanometer-sized PbBr2 particles on substrates by vapor deposition and then (2) growth of (C8H17NH3)2PbBr4 films by exposing PbBr2 particles to C8H17NH3Br vapor. Atomic force microscope observations reveal that the substrate is fully covered with nanometer-sized rodlike precipitates. X-ray diffraction studies suggest that (C8H17NH3)2PbBr4 films are found to be microcrystalline form, single phase and highly oriented with the c-axis perpendicular to the substrate surface. (C8H17NH3)2PbBr4 films show a clear exciton absorption and free-exciton emission even at room temperature. At low temperatures below 40 K, the emission band separates into three bands at 3.07 (A-band), 3.14 (B-band) and 3.20 (C-band) eV, respectively. Both A- and C-bands correspond to the free-exciton emission with large binding energies. On the contrary, time-resolved PL spectra indicate that the B-band is attributed to phosphorescence formed by the intersystem crossing. 相似文献
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Although SiO2 crystals have been used in electroluminescence devices and thermoluminescence (TL) dosimeters, the emission mechanism of TL has not yet been clearly explained. Recently, as we could get amorphous and highly pure SiO2 prepared by the sol-gel method, we have investigated the TL emission mechanism using Al3+- and/or Eu3+-doped SiO2 crystalline samples prepared by the heat-treatment under much lower temperature that the melting point of SiO2. The TL spectrum of the Eu3+-doped sample displayed several peaks, including two main peaks due to the electron transitions from 5D2 to 7F5 (ca. 570 nm) and from 5D0 to 7F2 (ca. 610 nm). As doping concentration increased, all the peak intensities reduced from maximum values except that due to the electron transition from 5D0 to 7F2. These observations are thought to result from a cross-relaxation process due to the lack of inversion symmetry at the Eu3+ site. 相似文献
108.
A new preconcentration method with yeast is presented. The method was evaluated for the determination of trace silver in river waters by graphite furnace atomic absorption spectrometry (GFAAS). A suitable cultivation bed for preconcentration of silver was 1.75 mg ml-1 2-ammonium hydrogen phosphate. The optimal cultivation time and temperature were 2 h and 25 degrees C. Under optimal conditions, silver in aqueous sample was concentrated to 6.9-fold by yeast. The detection limit was 4.6 pg ml-1 (3S/N) for silver in river water. The yeast preconcentration method was applied to the determination of silver in river waters. The recovery of spiked silver was in the range of 89 to 110%. By the preconcentration, it was found that ultra trace silver in river waters could be determined without interferences of matrix elements, after only the cultivation and with no chemical treatment. 相似文献
109.
Values of the molecular electrostatic potential minimum (V(min)) corresponding to the lone pair region of several substituted phosphine ligands (PR(3)) have been determined at the DFT level. The V(min) value is proposed as a quantitative measure of the electronic effect of the PR(3) ligands. Good linear correlation between V(min) and Tolman electronic parameter of PR(3) has been obtained. V(min) is also proportional to the pK(a) values of the conjugate acids of PR(3), viz., [PR(3)H](+). Further, the DeltaE values of the reaction Ni(CO)(3) + PR(3) --> Ni(CO)(3)PR(3) and ScH(3) + PR(3) --> ScH(3)PR(3) are also linearly proportional to the V(min) values. However, if there is a strong metal to phosphorus pi-back-bonding, the DeltaE and V(min) do not fit to a line. It is also found that the standard reduction potential as well as the enthalpy change corresponding to the electrochemical couple eta-Cp(CO)(PR(3))(COMe)Fe(+)/eta-Cp(CO)(PR(3))(COMe)Fe(0) is linearly proportional to the V(min) values of PR(3). These correlations suggest that V(min) is a quantitative measure of the sigma-donating ability of the phosphine. It is hoped that, in phosphine-metal coordination chemistry, the V(min) based electronic parameter could be more advantageous than nu-CO and pK(a) based electronic parameters as it solely represents the inherent electronic property of the ligand. 相似文献
110.
Newly designed homodesmotic reactions based on radical systems predict an absolute aromaticity of 29.13 kcal/mol for benzene and an absolute antiaromaticity of 40.28 kcal/mol for cyclobutadiene at the MP4(SDQ)/6-31G(d,p) level. 相似文献