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21.
Atsuya Muranaka Masaki Yokoyama Yotaro Matsumoto Masanobu Uchiyama Akihiko Tsuda Atsuhiro Osuka Nagao Kobayashi 《Chemphyschem》2005,6(1):171-179
The magnetic circular dichroism (MCD) spectra of doubly and triply linked fused bisporphyrins (2MD and 2MT, M = Ni, Zn, Cu, Pd, and H2) and triply linked higher oligomers (3ZnT and 4ZnT) have been measured, and their Q-bands assigned based on the results of INDO/s calculations. In contrast to the Faraday A term observed for the Q(0,0) band of Ni(II) tetraphenylporphyrin, a single positive Faraday B term was observed for the lowest energy transition of the fused systems. The calculations indicated that the molecular orbitals (MOs) of the directly fused porphyrins consist of linear combinations of the constituent monomeric MOs, and that the effect of lowering the symmetry is always larger on the lowest unoccupied molecular orbital (LUMO) than on the highest occupied molecular orbital (HOMO). On the basis of Michl's perimeter model, these features can be correlated with the observed positive MCD signs in the near infrared region. A weak absorption band at 600-700 nm for the fused dimers can be assigned to a short-axis polarized Q transition. 相似文献
22.
23.
Hirotsugu Minami Wanhong Cai Tatsuya Kusumoto Kaiji Nishikawa Qiangbin Zhang Sadanobu Inoue Ikuo Atsuya 《Analytical sciences》2003,19(10):1359-1363
Isotope dilution analysis of the sub-microg l(-1) levels of selenite and selenate in natural water samples by microwave-induced nitrogen plasma mass spectrometry (MIP-MS) was performed. An appropriate amount of a spike solution containing 78Se-selenite and 78Se-selenate was added to the natural water sample to be analyzed. Both analytes in the water were then concentrated simultaneously by passing the sample through a column that was filled with an anionic exchange resin. After the concentration process, all of the selenite and some of the selenate on the resin were eluted by 0.03 M nitric acid. The residual selenate was eluted by 0.13 M nitric acid. The eluted sample solutions were injected into MIP-MS, and isotope dilution analyses were carried out. Selenite and selenate concentrations as low as 0.01 microg l(-1) in the natural water sample were successfully determined by the proposed method. 相似文献
24.
Summary 8-Hydroxyquinoline (8-HOQ) was used for the preconcentration of Cd, Cu, Mn, Pb and Zn from seawater prior to their determination by graphite furnace atomic absorption spectrometry using an inner miniature cup for solid sampling technique. The metal ions in seawater were precipitated quantitatively in the pH range 7–8.5 with 8-HOQ alone. The precipitate thus formed was directly analysed by an atomic absorption spectrometer equipped with a specially deviced graphite furnace and miniature cup. The present method was confirmed to be highly reliable for analysis of seawater. Detection limits (3b) for Cd(II), Cu(II), Mn(II), Pb(II) and Zn(II) are 1.4, 10, 5, 10, and 6 ng l–1, respectively, for the analysis of a 400-ml portion of seawater samples. Corresponding precision of 6–14% is typical for determination 5-fold above the detection limits.
Direkte Analyse von Feststoffproben durch AAS nach Anreicherung von Spurenelementen aus Meerwasser mit 8-Hydroxychinolin相似文献
25.
The determination of manganese in iron and steels by u.h.f. plasma torch spectrometry is described. The intensity of the Mn II 257.16-nm ion line decreased with increasing concentration of iron, whereas the intensity of the Mn I 403.07-nm atom line increased; only the Mn I 279.48-nm atom line showed constant intensity as the concentration of iron increased. This behavior can be explained in terms of plasma temperature. The effects of acids were examined; the influence of small amounts of diverse elements was depressed by a large amount of iron. A simple and rapid method for the determination of manganese in iron and steels was established, the relative standard deviation being 2.6 % for 0.10 % Mn. 相似文献
26.
Hayakawa J Ikegami M Mizutani T Wahadoszamen M Momotake A Nishimura Y Arai T 《The journal of physical chemistry. A》2006,110(46):12566-12571
Photochemical properties of trans-3,3',5,5'-tetramethoxystilbene (TMST) have been studied in various polar solvents. The Stokes shift of trans-TMST was found to be increased with increasing solvent polarity. The fluorescence lifetime of trans-TMST experienced a large solvent effect changing from 2.3 ns in cyclohexane to 16.6 ns in acetonitrile. These results indicate that the excited singlet state of trans-TMST has a charge-transfer (CT) character. On the basis of the obtained results, the interior polar environment of a water-soluble TMST dendrimer is discussed. 相似文献
27.
Naoyuki Toriumi Norihito Asano Takayuki Ikeno Atsuya Muranaka Kenjiro Hanaoka Yasuteru Urano Masanobu Uchiyama 《Angewandte Chemie (International ed. in English)》2019,58(23):7788-7791
Near‐infrared (NIR) imaging techniques have attracted significant attention for biological and medicinal applications due to the ability of NIR to penetrate deeply into tissues. However, there are very few stable, activatable molecular probes that can utilize NIR light in the wavelength range beyond 800 nm. Herein, we report a new activatable NIR system for photoacoustic imaging based on tautomeric benziphthalocyanines (BPcs). We found that the existence of a free hydroxyl group is crucial for NIR absorption of BPcs. Synthesized water‐soluble hydroxy BPcs exhibited high photostability and no fluorescence, which are desirable features for photoacoustic imaging. We synthesized BPcs in which the free hydroxyl group was masked by an esterase‐labile or an H2O2‐labile group. The photoacoustic signals of these hydroxy‐masked BPcs were increased upon NIR excitation at 880 nm in the presence of esterase or H2O2, respectively. These are rare examples of activatable probes utilizing NIR light at around 900 nm. 相似文献
28.
Yusuke Tanaka Tomotaka Murayama Dr. Atsuya Muranaka Dr. Eiyu Imai Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(8):1768-1771
We designed and synthesized a new type of small helical molecule exhibiting intense circularly polarized luminescence (CPL) ( 12H ) by modifying a 20π-electron hemiporphyrazine with a large transition magnetic dipole moment. The hemiporphyrazine ring was opened and one additional pyridine unit was introduced, resulting in an overlap of two pyridine rings. X-ray structure analysis confirmed that 12H and its zinc complex ( 1Zn ) adopt a helical geometry. A racemic mixture of 1Zn was resolved into two enantiomers ((P)- and (M)- 1Zn ), which exhibited CPL with a high luminescence dissymmetry factor (glum) value of ±2.1×10−2. The origin of the large glum value was rationalized by means of DFT calculations. Helical structures could be formed in a diastereoselective manner by covalently attaching chiral units to the skeleton ( 1’2H and 1’Zn ). 1Zn was found to possess chiral recognition ability for amines. 相似文献
29.
A novel low-symmetry tetrabenzoporphine with D2h symmetry (1) and its zinc complex (2) were prepared via mixed condensation reaction of 5,6-dimethyl phthalimide and 4,5,6,7-tetraphenyl phthalimide with sodium acetate in the presence of zinc acetate. The zinc complex 2 exhibited a split Q band at 640 and 623 nm and a single Soret band at 435 nm. The absorption spectra of 1 and 2 were calculated and analyzed using Hartree-Fock theory based on INDO/S Hamiltonian. 相似文献
30.
Muranaka A Shibahara M Watanabe M Matsumoto T Shinmyozu T Kobayashi N 《The Journal of organic chemistry》2008,73(22):9125-9128
A racemic mixture of three-layered [3.3]paracyclophane ([3.3]PCP), 1, has been resolved into two enantiomers, and their absolute configuration was determined from a comparison of experimental chiroptical properties and density functional theory (DFT) calculations. A simple model comprising two p-xylenes and 1,2,4,5-tetramethylbenzene (durene) was used to explain the origin of the chiroptical properties of the three-layered cyclophane system. 相似文献