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- 저자 : Okujima, Tetsuo (검색결과 3 건)
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Kim, Pyosang,Sung, Jooyoung,Uoyama, Hiroki,Okujima, Tetsuo,Uno, Hidemitsu,Kim, Dongho American Chemical Society 2011 The journal of physical chemistry. B, Condensed ma Vol.115 No.14
<P>We have investigated the role of fused benzo rings on the electronic structures and intramolecular energy relaxation dynamics in a series of benzoporphyrins (<B>Bp1</B>, <I>syn</I>-<B>Bp2</B>, <I>anti</I>-<B>Bp2</B>, <B>Bp3</B>, and <B>Bp4</B>) by using time-resolved fluorescence measurements and theoretical calculations. Interestingly, even though <I>anti</I><B></B>- and <I>syn</I><B></B>-<B>Bp2</B> have the same number of fused benzo rings, in the respective absorption spectra, <I>anti</I><B></B>-<B>Bp2</B> shows an obvious splitting of B<SUB><I>x</I></SUB> (Q<SUB><I>x</I></SUB>) and B<SUB><I>y</I></SUB> (Q<SUB><I>y</I></SUB>) states, whereas <I>syn</I>-<B>Bp2</B> exhibits degenerate B and Q bands. These features provide two dynamical models for the effect of the position of substituted benzo rings on the intramolecular energy relaxation dynamics. <I>syn</I>-<B>Bp2</B> gives rise to similar intramolecular dynamics from the B state to the Q state in the case of <B>ZnTPP</B> having <I>D</I><SUB>4<I>h</I></SUB> molecular symmetry. On the other hand, <I>anti</I>-<B>Bp2</B> shows split B and Q bands in the order B<SUB><I>y</I></SUB> > B<SUB><I>x</I></SUB> > Q<SUB><I>x</I></SUB> > Q<SUB><I>y</I></SUB>, which leads a superimposition of the Q<SUB><I>x</I></SUB> (0,0) and Q<SUB><I>y</I></SUB> (1,0) bands. This overlap generates a strong coupling between these two states, which results in a direct internal conversion from B<SUB><I>x</I></SUB> (0,0) to Q<SUB><I>y</I></SUB> (0,0). This observation suggests that the anti-type fused position of benzo rings leads to a new mechanism in internal conversion from the B to the Q state. On the basis of this work, further insight was obtained into the effect of fused benzo rings on the photophysical properties of benzoporphyrins, providing a detailed understanding of the structure−property relationship in a series of benzoporphyrins.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2011/jpcbfk.2011.115.issue-14/jp200493p/production/images/medium/jp-2011-00493p_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp200493p'>ACS Electronic Supporting Info</A></P>
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Synthesis and photochemical properties of α-diketoporphyrins as precursors for π-expanded porphyrins
Yamada, Hiroko,Kuzuhara, Daiki,Ohkubo, Kei,Takahashi, Tetsuro,Okujima, Tetsuo,Uno, Hidemitsu,Ono, Noboru,Fukuzumi, Shunichi The Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.15
<p>A new α-diketoporphyrin and the corresponding Pd complex were prepared from the monoanthroporphyins and their photochemical properties were investigated by measurements of absorption and emission spectra, fluorescence lifetimes, laser flash photolysis, cyclic voltammetry, and theoretical calculations. Intramolecular electron transfer from the porphyrin singlet excited state to the diketone moiety was observed for the free base α-diketoporphyrin in benzonitrile, but this was not observed in toluene. Photoreactivity of the α-diketoporphyrins was also examined by irradiation at the Soret and Q bands. When the Soret band of the freebase α-diketoporphyrin was irradiated, cleavage of the diketone moiety occurred to afford the monoanthroporphyrin with the release of two CO molecules quantitatively in both benzonitrile and toluene. When the Q band of the freebase α-diketoporphyrin was irradiated, no photocleavage reaction occurred in toluene. In contrast to the freebase α-diketoporphyrin, the photocleavage reaction of the Pd complex occurred with irradiation at the Q band as well as the Soret band to afford the monoanthroporphyrin quantitatively in toluene. The photocleavage reaction proceeded much more effectively in toluene than in benzonitrile. The occurrence of rapid photoinduced electron transfer from the singlet excited state porphyrin to the diketone moiety, which was detected by femtosecond laser flash photolysis measurements, results in a significant decrease in the singlet excited state lifetime, prohibiting the photocleavage reaction in benzonitrile. Thus, the Pd α-diketoporphyrin can act as an excellent precursor for the corresponding acene in toluene. The photocleavage process provides a convenient and inexpensive method to make the thin film.</p> <P>Graphic Abstract</P><P>A new α-diketoporphyrin and its Pd complex were prepared and successfully converted into the corresponding monoanthroporphyins by photoirradiation of the porphyrin moieties with release of two CO molecules quantitatively. <img src='http://pubs.rsc.org/ej/JM/2010/b923220f/b923220f-ga.gif'> </P>
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