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351.
Treatment of (NH4)[Au(D‐Hpen‐S)2](D‐H2pen = D‐penicillamine) with CoCl2·6H2O in an acetate buffer solution, followed by air oxidation, gave neutral AuICoIII and anionic AuI3CoIII2 polynuclear complexes, [Au3Co3(D‐pen‐N,O,S)6]([ 1 ]) and [Au3Co2(D‐pen‐N,S)6]3? ([ 2 ]3?), which were separated by anion‐exchange column chromatography. Complexes [ 1 ] and [ 2 ]3? each formed a single isomer, and their structures were determined by single‐crystal X‐ray crystallography. In [ 1 ], each of three [Au(D‐pen‐S)2]3?metalloligands coordinates to two CoIII ions in a bis‐tridentate‐N,O,S mode to form a cyclic AuI3CoIII3 hexanuclear structure, in which three [Co(D‐pen‐N,O,S)2]? octahedral units and six bridging S atoms adopt trans(O) geometrical and R chiral configurations, respectively. In [ 2 ]3?, each of three [Au(D‐pen‐S)2]3? metalloligands coordinates to two CoIII ions in a bis‐bidentate‐N,S mode to form a AuI3CoIII2 pentanuclear structure, in which two [Co(D‐pen‐N,S)3]3? units and six bridging S atoms adopt ∧ and R chiral configurations, respectively. 相似文献
352.
Ryuji Nakao Takehito Ito Kazutaka Hayashi Toshimitsu Fukumura Kazutoshi Suzuki 《Journal of chromatography. A》2009,1216(18):3933-3940
A rapid and efficient preparative high-performance liquid chromatographic procedure was established to purify short-lived positron emission tomography radio-probes. This method is based on hydrophilic interaction chromatography utilizing a semi-preparative silica column (10 mm I.D.) and a high volatile organic mobile phase (>90% acetonitrile). In nine different radiopharmaceuticals studied, six compounds could be separated from the unlabeled precursor with good resolution and faster elution than its precursor. These characteristics enabled significant shortening of the separation and evaporation processes in the manufacture of short-lived radiopharmaceuticals. Several 11C-radiopharmaceuticals could be prepared within one half-life of carbon-11 (20.4 min), including radiosynthesis, purification and formulation steps with sufficient radiochemical/chemical purity and high levels of radioactivity/specific radioactivity. 相似文献
353.
Zhang X Takeguchi M Hashimoto A Mitsuishi K Tezuka M Shimojo M 《Microscopy and microanalysis》2012,18(3):603-611
Scanning confocal electron microscopy (SCEM) is a new imaging technique that is capable of depth sectioning with nanometer-scale depth resolution. However, the depth resolution in the optical axis direction (Z) is worse than might be expected on the basis of the vertical electron probe size calculated with the existence of spherical aberration. To investigate the origin of the degradation, the effects of electron energy loss and chromatic aberration on the depth resolution of annular dark-field SCEM were studied through both experiments and computational simulations. The simulation results obtained by taking these two factors into consideration coincided well with those obtained by experiments, which proved that electron energy loss and chromatic aberration cause blurs at the overfocus sides of the Z-direction intensity profiles rather than degrade the depth resolution much. In addition, a deconvolution method using a simulated point spread function, which combined two Gaussian functions, was adopted to process the XZ-slice images obtained both from experiments and simulations. As a result, the blurs induced by energy loss and chromatic aberration were successfully removed, and there was also about 30% improvement in the depth resolution in deconvoluting the experimental XZ-slice image. 相似文献
354.
Dr. Kenji Sugisaki Dr. Kazuo Toyota Prof. Dr. Kazunobu Sato Prof. Dr. Daisuke Shiomi Prof. Dr. Masahiro Kitagawa Prof. Dr. Takeji Takui 《Chemphyschem》2010,11(14):3146-3151
Zero‐field splitting (ZFS) tensors ( D tensors) of organic high‐spin oligonitrenes/oligocarbenes up to spin‐septet are quantitatively determined on the basis of quantum chemical calculations. The spin–orbit contributions, D SO tensors are calculated in terms of a hybrid CASSCF/MRMP2 approach, which was recently proposed by us. The spin–spin counterparts, D SS tensors are computed based on McWeeny–Mizuno’s equation in conjunction with the RODFT spin densities. The present calculations show that more than 10 % of ZFS arises from spin–orbit interactions in the high‐spin nitrenes under study. Contributions of spin‐bearing site–site interactions are estimated with the aid of a semi‐empirical model for the D tensors and found to be ca. 5 % of the D SO tensor. The analysis of intermediate states reveal that the largest contributions to the calculated D SO tensors are attributed to intra‐site spin flip excitations and delocalized π and π* orbitals play an important role in the inter‐site spin–orbit interactions. 相似文献
355.
The supramolecular organogelation of alcohols was observed in relatively hydrophobic amphiphiles with a short oligo(ethylene glycol) unit and three long alkyl chains at room temperature, while the hydrogelation occurred in more hydrophilic gelators with a longer poly(ethylene glycol) unit and two long alkyl chains at various temperatures. When a hot aqueous solution of some of the synthetic hydrogelators was cooled down, the supramolecular hydrogel was formed at room temperature. In some other amphiphiles with less intermolecular interactivity in water at room temperature, a reverse phase transition of sol to gel was observed by elevating the temperature of their aqueous systems, especially below a physiological temperature, 37 °C. The supramolecular hydrogelation at a low or high temperature was dependent on a slight molecular modification of the synthetic amphiphiles. 相似文献
356.
Toyota T Tsuha H Yamada K Takakura K Yasuda K Sugawara T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(5):1976-1981
Adding an artificial bolaamphiphile to a dispersion of giant multilamellar vesicles (GMVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) induced a cup-shaped deformation in GMVs accompanied by partial extrusion of the inner vesicle; thereafter, the deformed vesicles returned to their original shape. On the other hand, when the artificial bolaamphiphile together with a surfactant was added to the vesicular dispersion, these deformation and reformation dynamics were transmitted from the outer membranes in GMVs to the inner membranes until an intact inner vesicle was extruded out of the outer membrane. The microscopic aspects of these processes were investigated using amphiphiles tagged with individual fluorophores. 相似文献
357.
To construct a new type of chiral pi-conjugated system, the title anthracene-acetylene oligomer containing two octyl groups at position 10 of 1,2-alternating anthracene groups was synthesized. Each anthracene unit was connected by Sonogashira coupling, and the tetrameric precursor was cyclized by a cross-coupling reaction to form the desired C2-symmetric compound. Its enantiomers were resolved by chiral HPLC with a Chiralcel OD column, and the chiroptical properties were investigated by optical rotation ([alpha]D(23) = -95 and +91) and circular dichroism (CD) measurements. The structural and spectroscopic features of this oligomer were discussed in terms of the molecular symmetry and the dynamic behavior of the macrocyclic framework. 相似文献
358.
359.
Ju J Sasaki J Yang T Kasamatsu S Negishi E Li G Lin J Nojiri H Rachi T Tanigaki K Toyota N 《Dalton transactions (Cambridge, England : 2003)》2006,(13):1597-1601
A new nickel polyborate, NiB12O14(OH)10 was synthesized using boric acid as a flux. This material has two-dimensional borate layers with a quasi-square lattice of Ni2+. The Ni2+ ions locate in the plane of the two-dimensional layer, bridged through BnO(n+1) chains in the plane and connected with the three-membered ring borate groups out of the plane. The dc and ac magnetic susceptibility, magnetization and specific heat measurements show that this material undergoes a weak ferromagnetic phase transition at Tc = 5.8 K. At T < Tc, a metamagnetic phase transition is observed at about 5 T, associated by a spin-flop, suggesting the ferromagnetic ordering is induced by an antiferromagnetic interaction. A broad maximum in the ac susceptibility at TM = 23-24 K indicates an intermediate short-range ordering. 相似文献
360.
A convergent total synthesis of (+)-mycalamide A is described. A Yb(OTf)3-TMSCl catalytic system is used to synthesize a trioxadecalin ring system, which contains the right segment of mycalamide A. In addition, a tetrahydropyran ring, which is the left segment, is constructed with use of a novel one-pot delta-lactonization protocol. Both segments are prepared from a common starting material, d-mannitol. These segments are then coupled and the functional groups are transformed to synthesize (+)-mycalamide A. 相似文献