ON THE SYNTHESES AND PHOTOCHEMICAL PROPERTIES OF NOVEL PYRROLIZINONE DERIVATIVES AS PHOTOSENSITIZERS

The syntheses of the pyrrolizinone derivatives 8H-6-methyl-7-phenylthieno[2,3-b]-pyrrolizin-8-one (1), 10H-6,7,8,9-tetrahydro(1)benzothieno[2,3-b]pyrrolizin-10-one (2), 8H-6-phenylthieno[2.3-b]pyrrolizin-8-one (3), 8H-methylthieno[2,3-b]pyrrolizin-8-one (4), are described. In contrast to benzophenone, compounds 1 - 4 absorb in the visible light region (epsilon436 nm - = 400, 420, 450, and 320 1 mol-1 cm-1 for compounds 1 - 4, respectively). 9-Fluorenone as well as compounds 1 - 4 were able to reduce methylviologen in the presence of 2-propanol under irradiation with UV light (A > 280 nm). Compounds 1 - 4 showed an interesting fluorescence behavior depending on solvent and on Ph - value, which will be discussed in detail.