Fluorometric Study on the Metal Chelates of Flavone Derivatives. II. Correlation between Fluorescence Emission and the Carbonyl Stretching Frequency
1971 年 19 巻 4 号 p. 792-795
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1971 年 19 巻 4 号 p. 792-795
In the present paper, it has been described on a relationship between the fluorescence emission and the carbonyl stretching frequency of flavone derivatives. Non-fluorescent ligands (type I, III in Chart 1) show their carbonyl frequencies in the 1645-1650 cm-1 region, while fluorescent ligands (type II, IV) give those in the 1610-1620 cm-1 region and cause a remarkable increase of the fluorescence intensity by forming of chelates with some metals such as beryllium, aluminum, magnesium, thorium, yttrium. Further evidence is found by examining the chemical shift of 2-proton in several chromone derivatives. That of 3-hydroxychromone is noteworthily lower than those of the other chromone derivatives, indicating the more aromaticity of its pyrone ring. From these data, it is concluded that introduction of a hydroxyl group into 3-position of flavone causes the remarkable lowering of carbonyl frequency and the increase of aromaticity of pyrone ring, which is very likely responsible for the fluorescence emission.
