Photochemistry of nonconjugated bichromophoric systems .2. Photocyclization reaction and fluorescence spectra studies of long chain biscoumarins

A series of polymethylene bis (4-methyl-7-coumarinyl)oxyacetates have been synthesized and their photochemical reaction and fluorescence spectra have been studied. It was found that only intramolecular photocyclization products were obtained when polymethylene his (4-methyl-7-coumarinyl)oxyacetates were directly irradiated in chloroform. The yields of the products decreased with the increase of methylene chain lengths, and this result accords with the phenomena found in the fluorescence spectra, i.e., the relative fluorescence intensity increased with the increase of methylene chain length.