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1997 (1)
1978 (1)
1976 (1)
1Author    Shozi Yamashita, Mizuki Yoshida, Giiti TomitaRequires cookie*
 Title    Photoionization of Indole in Alkaline Aqueous Solutions at 77 °K  
 Abstract    The photoionization process of indole in alkaline aqueous solutions at 77 °K and the recombination process of trapped electron with its mother molecule were investigated. The fluorescence spectrum of indole in these glassy media depended on the NaOH concentration; the disappearance of the 325 nm band at the NaOH concentrations higher than 5 M with the appearance of a fluorescence band at 375 nm. The latter emission is possibly ascribed to the fluorescence of indole anion formed by proton dissociation in the excited singlet state of indole. The intensities of the 375 nm band and the ESR signal due to trapped electrons were dependent on the NaOH concentration and increased steeply with increasing the NaOH concentration. There was a parallel relation between the indole anion concentration and the trapped electron density to some extent. The dependence of the ESR signal intensity on irradiation intensity suggested that the photoionization of indole in alkaline aqueous solution occurred through a two photon process. The presence of a photoactive intermediate for absorbing the second photon was further investigated with simultaneous irradiation of two different wavelength lights. The trapped electron was detrapped with the irradiation of visible light (e.g. 580 nm), and its recombination with mother molecule caused an emission with the same spectrum as indole phosphorescence. The molecular species of the photoactive intermediate in alkaline aqueous solutions seems to be the indole anion. The photoionization in NaOH aqueous solution at 77 °K was also compared with that in methanolic glassy solution. 
  Reference    (Z. Naturforsch. 31b, 361—366 [1976]; received April 28/July 22 1975) 
  Published    1976 
  Keywords    Photoionization, Phosphorescence, ESR, Trapped Electron, Indole 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0361.pdf 
 Identifier    ZNB-1976-31b-0361 
 Volume    31 
2Author    Shozi Yamashita, Giiti TomitaRequires cookie*
 Title    The Delayed Fluorescence of Indole in Alcohol-Alkane Mixed Glasses at 77 K  
 Abstract    Using a phosphoroscope and a pulsed light-signal integrator, the effect of alcohol on the delayed fluorescence of indole was investigated in alcohol-isopentane mixed glasses at 77 K. The delayed fluorescence intensity was strongly depended on the alcohol concen-tration and the polarity of alcohol. Trapped electrons causing the delayed fluorescence were separated into two species utilizing the scavenge effect of CCI4; shallow trapped-electrons sensitive to CCI4 and deep trapped-electrons insensitive to CCI4. The former electrons seem to be responsible for the delayed fluorescence at low alcohol concentrations, whereas the latter for the delayed fluorescence at higher alcohol concentrations. The delayed fluorescence decayed exponentially at low alcohol concentrations, but it decayed with the Debye-Edwards law of t" 1 at higher alcohol concentrations. The recombination mechanism of trapped electrons with parent cations was discussed. The structure of shallow traps was also estimated. 
  Reference    Z. Naturforsch. 33b, 1136—1141 (1978); received March 29 1978 
  Published    1978 
  Keywords    Delayed Fluorescence, Indole, Trapped Electron, Trapping State 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-1136.pdf 
 Identifier    ZNB-1978-33b-1136 
 Volume    33 
3Author    Z. NaturforschRequires cookie*
 Title    Acyclo C-Nucleosides Analogues of Condensed 1,2,4-Triazines  
 Abstract    1-Acyclo C-nucleosides of 7-methyl-10//-l,2,4-triazolo[3,,4':3,4][l,2,4]triazino[5,6-£>]indoles (9) have been prepared by cyclodehydrogenation of the sugar derivatives of 3-hydrazino-8-methyl-5//-l,2,4-triazino[5,6-6]indole (1). The respective linear isomer as 4 has been pre­ pared by a dehydrative cyclization of the amides of 1. Acetylation of the sugar hydrazones and their cyclized products gave the per-7V,0-acetyl derivatives. The molecular connectivity of the products was established by *H, 13C, and 2D H ,H Cosy spectra. 
  Reference    Z. Naturforsch. 52b, 873—882 (1997); received February 17 1997 
  Published    1997 
  Keywords    Acyclo C-Nucleoside, 1, 2, 4-Triazine, Indole, Triazinoindole, Triazolotriazinoindole 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-0873.pdf 
 Identifier    ZNB-1997-52b-0873 
 Volume    52