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321.
Nobuhiko Iki Dr. Munehiro Ohta Takayuki Horiuchi Dr. Hitoshi Hoshino Prof. 《化学:亚洲杂志》2008,3(5):849-853
The compositions and photophysical properties of luminescent ternary complexes of thiacalix[4]arene‐p‐sulfonate (TCAS), TbIII, and AgI ions were determined. At pH 6, AgI2?TbIII2?TCAS2 formed. Moreover, at pH 10, in the presence of a 20‐fold excess of AgI and a 50‐fold excess of TCAS with respect to TbIII, AgI2?TbIII?TCAS2 formed as the main luminescent species. The structure of these complexes was proposed: two TCAS ligands are linked by two S–AgI–S linkages to adopt a double‐cone supramolecular structure. Furthermore, each TbIII ion in the former complex accepts O?, S, O? donation, whereas in the latter, the TbIII center accepts eightfold O? donation. The luminescence quantum yield (Φ) of AgI2?TbIII2?TCAS2 (0.16) was almost equal to that of TbIII?TCAS, but the luminescence lifetime τ of the former (=1.09 ms) was larger than that of the latter. For AgI2?TbIII?TCAS2, the yield Φ (=0.11) was small, which is attributed to the low efficiency of photosensitization (η=0.11). However, the τ value (4.61 ms) was exceptionally large and almost equal to the natural luminescence lifetime of TbIII (4.7 ms), which is due to the absence of coordinating water molecules (q=0.1). This is compatible with the proposed structure in which the TbIII ion is shielded by a supramolecular cage that expels coordinated water molecules responsible for luminescence quenching. 相似文献
322.
An efficient approach to benzoxazoles via tandem migration-carboalkoxylation of o-isocyanophenyl acetals has been developed. Both a Lewis acid and base are essential for this reaction, and the BF(3)·OEt(2)/2,4,6-collidine combination is the best choice for cooperative transformation. 相似文献
323.
Bouras G Nakanishi T Fujita Y Tsunemi S Takubo T Tanigawa N 《Analytical and bioanalytical chemistry》2012,403(7):1801-1809
324.
Kajiwara T Katagiri K Hasegawa M Ishii A Ferbinteanu M Takaishi S Ito T Yamashita M Iki N 《Inorganic chemistry》2006,45(13):4880-4882
Dinuclear and cubane-shaped lanthanide cluster complexes containing EuIII)and TbIII were synthesized by step-by-step construction using p-tert-butylsulfonylcalix[4]arene as a cluster-forming ligand. The sulfonylcalixarene adopts a pinched-cone conformation in the dinuclear complexes and a cone conformation in the cubane complexes. Because the calixarene has a large pi-conjugate system expanding over the entire molecule, it behaves as a good antenna chromophore for UV and near-UV light, and a slight conformational change of the calixarene (from cone to pinched-cone and vice versa) has an effect on the energy levels of excited S1 and T1 states. As a result, selectivity is observed in the luminescent properties of dinuclear and cubane-shaped systems of EuIII and TbIII. 相似文献
325.
Molecular mobility of interlocked structures exploiting new functions of advanced biomaterials 总被引:1,自引:0,他引:1
Cyclic compounds can rotate and/or slide along a polymeric chain in a polyrotaxane structure, and the mobility of the ligands linked by the cyclic compounds is closely related to enhancing the multivalent interaction with binding sites on the receptor proteins. This concept is being exploited in more practical applications in the biomedical and pharmaceutical fields, such as a non-viral gene carriers. 相似文献
326.
An InP-based Mach-Zehnder interferometer combined with a metamaterial layer consisting of a split-ring resonator array was constructed to measure the complex permeability of the metamaterial. At a wavelength of 1.5 μm, the metamaterial showed non-unity relative permeability induced by magnetic interaction with propagating light in the device. This method of measurement would be useful to determine constitutive parameters in such waveguide-based photonic devices, allowing us to design photonic integrated circuits that make use of metamaterials. 相似文献
327.
Bernard Mehlig Nobuhiko Taniguchi 《Physica E: Low-dimensional Systems and Nanostructures》1999,4(4):316
Fluctuations of expectation values of observables are calculated in complex quantum systems, such as disordered metallic grains or quantum systems with classical chaotic motion. We derive an exact expression for these fluctuations valid for systems with and without time-reversal symmetry, as well as in the transition region between these two cases. We compare our results with those of a semiclassical theory and with simulations of random matrices. 相似文献
328.
329.
Liu Zhenlin Ohtake Hideyuki Izumida Shinji Ono Shingo Sarukura Nobuhiko 《Optical and Quantum Electronics》2000,32(4-5):521-529
The THz-radiation power from InAs reaches sub-mW level in a 1.7-T magnetic field irradiated with femtosecond laser pulses of 1.5-W average power. The THz-radiation power is related almost quadratically both to the magnetic field and to the excitation laser power. Furthermore, the THz-radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field. 相似文献
330.
The ZnSe : N epitaxial layers were grown on (1 1 0) ZnSe substrates in a low-pressure metalorganic chemical vapor deposition (MOCVD) system using hydrogen as a carrier gas, and using ammonia as a dopant source. In order to obtain highly doped ZnSe : N epitaxial layers, the optimum growth and doping conditions were determined by studying the photoluminescence (PL) spectra from the ZnSe epitaxial layers grown at different ammonia flux and VI/II flux ratio. Furthermore, in order to enhance the concentration of active nitrogen in ZnSe epitaxial layer, a rapid thermal anneal technique was used for post-heat-treating. The results show that the annealing temperature of over 1023 K is necessary. Beside, a novel treatment method to obtain a smooth substrate surface for growing high quality ZnSe epitaxial layers is also described. 相似文献