Isomerization of Diphenyl Polyenes. Part VII. The effect of Daylight and Direct Irradiation

Photoisomerization of l,4-diphenyl-l,3-butadiene (DPB), l,6-diphenyl-l,3,5-hexatriene (DPH) and l,8-diphenyl-l,3,5,7-octatetraene (DPO) in polyvinyl alcohol) (PVA) films was studied unter daylight and direct irradiation. The most efficient photoisomerization occurs in the DPB molecule, the smallest among the compounds investigated. For the greatest, DPO, molecule no distinct isomerization was observed in daylight and only a temperature effect was noted. Therefore, the DPO molecule in the PVA film heated to 423 K may serve as a fluorescence standard.