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71.
72.
Synthesis,Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems
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Prof. Dr. Tetsuo Okujima Dr. John Mack Dr. Jun Nakamura Gugu Kubheka Prof. Dr. Tebello Nyokong Dr. Hua Zhu Naoki Komobuchi Prof. Dr. Noboru Ono Prof. Dr. Hiroko Yamada Prof. Dr. Hidemitsu Uno Prof. Dr. Nagao Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14730-14738
A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro‐Diels–Alder reaction of bicyclo[2.2.2]octadiene‐fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time‐dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π‐molecular orbitals. 相似文献
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Abstract A model for calculation of the range distribution of energetic ions with taking into account the channeling effect is proposed. The measurement of the depth distributions of boron ions in silicon crystals implanted at 13.6 and 91 MeV revealed significant difference between the measured and the calculated range profiles when the channeling effects have not been included in the calculation. In spite of deminishing the critical angles of channeling with growing ion energy the probability of the capture of ions into the channeling regime is significant in case of high energy implantation even when the incident angles are 7–10° off the main crystallographic directions. 相似文献
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Michelle Hampson Naomi Driesen Jennifer K. Roth John C. Gore R. Todd Constable 《Magnetic resonance imaging》2010
Functional brain imaging studies have identified a set of brain areas typically activated during cognitive tasks (task-positive brain areas) and another set of brain areas typically deactivated during cognitive tasks (task-negative brain areas). Negative correlations, or anticorrelations, between task-positive and task-negative brain areas have been reported at rest. Furthermore, the strength of these anticorrelations appears to be related to cognitive function. However, studies examining anticorrelations have typically employed global regression or similar analysis steps that force anticorrelated relationships to exist between brain areas. Therefore the validity of these findings has been questioned. Here we examine anticorrelations between a task-negative region in the medial frontal gyrus/anterior cingulate cortex and dorsolateral prefrontal cortex, a classic task-positive area, using an analysis that does not include global regression. Instead, we control for whole-brain correlations in the group-level analysis. Using this approach, we demonstrate that the strength of the functional connection between the medial frontal cortex and the dorsolateral prefrontal cortex is related to cognitive function and that this relationship is not an artifact of global regression. 相似文献
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Takeshi Eitoku Kazuya Taniguchi Yuta Nakazato Shunichi Ono Kenji Katayama 《Optical Review》2010,17(1):5-9
Formation process of gold nanoparticles was investigated by near-field heterodyne transient grating method. In the absence
of the protective agents, although the diffusion of H[AuICl2] could be observed after the photo-reduction of H[AuIIICl4], the diffusion of nanoparticle-seeds was not observed. On the other hand, in the presence of the protective agents, the
diffusion of a complex molecule (Au and protective agent) and nanoparticle-seeds could be observed. From these results, it
was found that enough amount of the complex is essential for the nanoparticle formation. We also investigated the formation
process with four different chemicals as a protective agent. The hydrodynamic radius of nanoparticle-seeds generated in the
poly(vinyl pyrrolidone) and TritonX-100 solutions were larger than those generated in the Tween 20 and Brij 58 solutions.
The former two have hydrophilic chain in the molecular structure; on the other hand, the latter two have hydrophobic alkyl
chain. Based on those facts, we concluded that the interaction between the chains of the complex molecule plays an important
role in the nanoparticle formation process. 相似文献
80.
Eiichi Kimura Naomi Katsube Tohru Koike Motoo Shiro Shin Aoki 《Supramolecular chemistry》2013,25(2-3):95-102
We have previously shown that the nucleobase thymine binding to Zn2+ -cyclen (cyclen=1,4,7,10-tetraazacyclododecane) complex became stronger by appending acridine, naphthalene, or quinoline rings to the cyclen. Amongst these, the pendant bis((1-naphthyl)methyl) or bis((4-quinolyl)methyl) groups yielded the most effective thymine-recognizing Zn2+ -cyclen complexes [J. Am. Chem. Soc., 121 (1999) 5426]. The present study was undertaken to find causes of the bis(aromatic) ring effect by X-ray crystal structure analysis and NMR studies. The crystal structure of the Zn2+ -bis((1-naphthyl)methyl)-cyclen complex with a deprotonated 1-methylthymine (1-MeT) failed to show the anticipated evidence for the double ~ - ~ stacking interactions between the two naphthalenes and the Zn 2+ -bound 1-MeT m (1-MeT m =N(3')-deprotonated 1-MeT). Crystal data: formula C36 H47 N7 O7 Zn, M r =755.19, monoclinic, space group P21/ c (No. 14), a =15.438(2) Å, b =14.093(3) Å, c =16.726(2) Å, g =90.53(1) V =3638.7(8) Å 3 Z =4, R =0.035, R w =0.049. However, the 1H NMR studies of Zn2= -bis((4-quinolyl)methyl)-cyclen with 1-MeT in varying H2O/CH3 CN solution showed increasing upfield shifts of Me(5') and H(6') of the Zn2+ -bound 1-MeT in more aqueous media, indicating that the double intercalation with the two quinolines became more significant in more protic environments. We conclude that the double ~ - ~ stacking effect accounts for the enhanced recognition of thymine base by the appended bis((1-naphthyl)methyl) or bis((4-quinolinyl)methyl) groups. 相似文献