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911.
Atsumi Yagi Takeshi Kondo Daisuke Yamashita Naruhiko Wachi Hiroto Omori Dr. Norihito Fukui Prof. Dr. Takahisa Ikeue Prof. Dr. Hiroshi Shinokubo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15580-15585
Oxidation of 5,15-dithiaporphyrin with meta-chloroperbenzoic acid afforded the corresponding S,S-tetraoxide in good yield. The resultant 5,5,15,15-tetraoxo-5,15-dithiaporphyrin exhibited the highly electron-deficient nature as elucidated by the electrochemical analysis and theoretical calculations. Treatment of tetraoxodithiaporphyrin with zinc(II) acetate and nickel(II) acetate provided the corresponding metal complexes efficiently. Owing to its enhanced Lewis acidity of the metal center by the electron-deficient ligand, the nickel complex underwent facile axial ligation to form pentacoordinate and hexacoordinate high-spin (S=1) complexes in solution and solid, respectively. The binding constant of pyridine to the NiII center was significantly higher than those of conventional porphyrin NiII complexes. Temperature-dependent magnetic susceptibility measurements of the high-spin NiII complex revealed the presence of weak ferromagnetic interactions. 相似文献
912.
Dr. Sunri Lee Dr. Ken-ichi Yamashita Naoya Sakata Dr. Yasukazu Hirao Kaya Ogawa Prof. Takuji Ogawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3240-3243
Dinuclear rare-earth (TbIII, YIII) triple-decker complexes with a fused diporphyrin (FP) and two tetraphenylporphyrin (TPP) ligands were synthesized in neutral, dianionic, and diprotonated forms. The neutral forms have large open shell biradical character, as determined from the temperature dependency of the magnetic susceptibility measurements and theoretical calculations. The coupling value (J=−1.4 kcal mol−1, −487 cm−1) of the radical centers in the neutral form of the YIII complex indicates weak pairing interactions. Theoretical calculations on the neutral form reveal a significant biradical character (y=68 %). Furthermore, the TbIII complex exhibits multi-redox states, having more than eight clear peaks in the voltammetry curves. The optical (3700 nm, 0.33 eV) and electrochemical measurements (3400 nm, 0.36 eV) indicate that the neutral form has very small HOMO–LUMO energy gap. Despite the large biradical character, the neutral complexes are thermally stable and do not decompose on heating at 120 °C. These complexes with unique characteristics are promising candidates for use in molecular electronics, optics, and spintronics. 相似文献
913.
Keishiro Yamashita Kazuki Komatsu Stefan Klotz Maria T. Fernández-Díaz Oscar Fabelo Tetsuo Irifune 《高压研究》2020,40(1):88-95
ABSTRACTA high-pressure cell for in-situ single-crystal neutron diffraction was developed. The cell uses nano-polycrystalline diamond anvils in a tubular load frame made of bulk metallic glass which is highly transparent to neutrons and does not produce Bragg reflections. Diffraction peaks from a sample can be measured from almost any direction and the simple geometry of the cell allows accurate attenuation corrections. We demonstrate the operation of the cell by ambient-pressure experiment using a single-crystal of NaCl on the D9 diffractometer at the Institute-Laue-Langevin. A high-pressure experiment was also carried out on a single crystal of ice VII at 2.35?GPa showing the potential to detect weak diffraction spots. The correct integration of weak reflections together with the simple attenuation correction will help to carry out precise structure analysis and address new scientific problems using neutron diffraction. 相似文献
914.
David Chukwuma Izuogu Takefumi Yoshida Goulven Cosquer Jonnie N. Asegbeloyin Haitao Zhang Alex J. W. Thom Masahiro Yamashita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(27):6036-6049
Acetato-bridged palladium–lanthanide tetranuclear heterometallic complexes of the form [Pd2Ln2(H2O)2(CH3COO)10] ⋅ 2 CH3COOH [Ln2=Ce2 ( 1 ), Pr2 ( 2 ), Nd2 ( 3 ), Sm2 ( 4 ), Tb2 ( 5 ), Dy2 ( 6 ), Dy0.2Y1.8 ( 6′′ ), Ho2 ( 7 ), Er2 ( 8 ), Er0.24Y1.7 ( 8′′ ), Tm2 ( 9 ), Yb2 ( 10 ), Y2( 11 )] were synthesised and characterised by experimental and theoretical techniques. All complexes containing Kramers lanthanide ions [Ln3+=Ce ( 1 ), Nd ( 3 ), Sm ( 4 ), Dy ( 6 ), DyY ( 6′′ ), Er ( 8 ), ErY ( 8′′ ), Yb ( 10 )] showed field-induced slow magnetic relaxation, characteristic of single-molecule magnetism and purely of molecular origin. In contrast, all non-Kramers lanthanide ions [Ln3+=Pr ( 2 ), Tb ( 5 ), Ho ( 7 ), Tm ( 9 ), Y3+ ( 11 ) is diamagnetic and non-lanthanide] did not show any slow magnetic relaxation. The variation in the electronic structure and accompanying consequences across the complexes representing all Kramers and non-Kramers lanthanide ions were investigated. The origin of the magnetic properties and the extent to which the axial donor–acceptor interaction involving the lanthanide ions and an electron-deficient orbital of palladium affects the observed magnetic and electronic properties across the lanthanide series are presented. Unique consistent electronic and magnetic properties of isostructural complexes spanning the lanthanide series with properties dependent on whether the ions are Kramers or non-Kramers are reported. 相似文献
915.
Shuji Yamashita 《Tetrahedron》2011,67(35):6616-6626
Ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, are potent toxic polycyclic ethers. In this paper, we report a stereoselective and secure route to the left wing of Caribbean ciguatoxin on the basis of a 6-exo radical cyclization strategy. 相似文献
916.
Koji Takagi Hyunho Joo Yusuke Yamashita Eiki Kawagita Chikako Torii 《Journal of polymer science. Part A, Polymer chemistry》2011,49(18):4013-4020
2,5‐Dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene ( DBPyTh ) was synthesized by the Suzuki coupling reaction between two aromatic compounds followed by the bromination. The Grignard metathesis reaction of DBPyTh with isopropylmagnesium chloride proceeded in 85% conversion and the regioselective halogen–metal exchange at the 2‐position was confirmed. Namely, 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and 2‐bromo‐5‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene were generated in 90:10 molar ratio. Subsequently, the Kumada coupling polymerization was carried out using 1,3‐bis(diphenylphosphinopropane)nickel(II) dichloride to obtain poly(3‐(6′‐hexylpyridine‐2′‐yl)thiophene) ( PolyPyTh ). The polymer molecular weight could be roughly controlled by the catalyst concentration and the molecular weight distribution ranged from 1.25 to 1.80. The gas chromatograph analysis indicated that 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene was preferentially polymerized in 90% conversion and the percentage of the head‐to‐tail content (regioregularity) was calculated to be 96%. The matrix‐assisted laser desorption/ionization time‐of‐fright mass spectrum indicated that both polymer chain ends were substituted with the hydrogen atom. The absorption maxima of polymer in CHCl3 and thin film were observed at 447 and 457 nm, respectively, which were blue‐shifted compared with poly(3‐(4′‐octylphenyl)thiophene). From the CV measurement of the polymer thin film, highest occupied molecular orbital (HOMO) (?5.31 eV) and lowest unoccupied molecular orbital (LUMO) (?3.76 eV) energy levels were calculated from the oxidation and reduction onset potentials, respectively, and the electrochemical band gap energy was determined to be 1.62 eV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
917.
918.
919.
Successive structural transitions of KCdF3 and K0.5Rb0.5CdF3 have been studied by means of thermal diffusivity, polarized light scattering and X-ray diffraction. It is found that transitions occur at about 460 K and 475 K in KCdF3, and at 222 K, 232 K, 250 K, 258 K and 268 K in K0.5Rb0.5CdF3. The partial exchange between K+ and Rb+ ions gives rise to simultaneous condensation of the Mz 3 and Rx 25 soft phonons. 相似文献
920.