The iron-chlorophyllin complex was found to be chemiluminescent (CL) in an acetonitrile (22%)/water mixed solvent. In the presence of hydrogen peroxide, when iron-chlorophyllin was added to the mixed solvent, a sharp CL signal immediately appeared. Also, analysis of the absorption spectra revealed decomposition of iron-chlorophyllin (based on decrease in absorbance at 396 nm), hence iron-chlorophyllin is the CL substance. Moreover, the CL intensity decreased in the presence of potassium thiocyanate (KSCN), indicating that the axial coordinative position of iron-chlorophyllin acts as a point of catalytic activation. In addition, when fluorophores were present with iron-chlorophyllin CL, their CL intensity values were similar to or greater than that of the well-known trichlorophenylperoxalate ester (TCPO) CL. Thus, during the decomposition reaction of iron-chlorophyllin, the latter transfers its energy to the coexisting fluorophores. Moreover, since the decomposed compound in this CL reaction had a fluorescence, it was found that the iron-chlorophyllin also functions as an energy donor. Therefore, the iron-chlorophyllin complex acts not only as a CL substance, but also as a catalyst and energy donor in the reaction.
In the presence of acetonitrile and NaOH, when H2O2 was added to the solution containing chlorophyll, it was found that a strong chemiluminescence (CL) was emitted. The blue light was emitted with the decomposition of chlorophyll. It is considered that the emitter contains the decomposition products of chlorophyll based on the following measurement results, such as the reduction of absorbance for chlorophyll and the difference of the spectral form between fluorescence and CL. The CL of the chlorines, such as chlorophyll, and the porphyrin analogue compounds were compared under the same conditions. Consequently, the obtained CL was strong in the chlorin complex which contains Mg or Zn. On the other hand, the CL was not strongly observed with porphyrin compounds. In the chlorophyll CL, when the chlorin ring is oxidized by the generated •O2−, the excited molecule would be produced in the process of ring cleavage, and then CL is emitted to the outside.
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