Tamotsu Matsumoto

Intersystem crossing in 9-carbonyl derivatives of anthracene

Abstract An unusual temperature effect on the intensity of fluorescence of 9-carbonyl derivatives of anthracene is observed. This is interpreted in terms of an intersystem crossing process from the lowest excited singlet state S ππ * to the higher excited triplet state T nπ * .

Intersystem crossing of the carbonyl compounds of anthracene. (II). Derivatives of 9-benzoylanthracene

Abstract Among several derivatives of 9-benzoylanthracene investigated, only 9-benzoyl 10-cyanoanthracene having the largest λ o–o value showed a large temp

An efficient intersystem crossing mechanism revealed by a large temperature effect on the photochemical reactions of 9-α-Bromopropionylanthracene

Abstract A significant temperature effect on the new photochemical reactions of 9-α-bromopropionylanthracene has been noted. In comparison to the temperature effect on the fluorescence intensity of 9-propionylanthracene, it was suggested that the rotation of the carbonyl group on photo-excitation might operate as an enhancing factor in the intersystem crossing process.

Zone-refining of phenanthrene using chemical reactions in melted zone

The separation of trace amounts of anthracene from phenanthrene is very difficult even with the zonerefining method. The authors have found that the addition of a small quantity of maleic anhydride to the original phenanthrene sample greatly enhances the efficiency of zone-refining.Anthracene reacts with maleic anhydride in the melted zone of phenanthrene to form an addition compound whose segregation coefficient is much different from that of anthracene itself. Therefore, the efficiency of zone-refining is enhanced.The determination of anthracene was made by measuring the absorbance at 376 nm in cyclohexane; the limit of detection by this method was 0.002%. A commercial sample of guaranteed-grade phenanthrene contained about 1.2% anthracene. After 30 passes of the sample through the heated zone in the presence of 2.8% maleic anhydride, no anthracene could be detected in the purified product.The present technique of improving efficiency of the zone-refining method by adding a third substance which in the melted zone reacts with the impurity to form a compound of different segregation coefficient may be applied to various cases.