Dithiophene, photochemical

Benzo[l,2-A4,5- ]dithiophene 22 undergoes photochemical [2n+2n] cycloaddition with electron-deficient buta-diynes on irradiation at 300 nm to produce photoadducts in low yields. The reaction with dimethyl acetylenedicar-boxylate proceeds directly to produce the secondary photoadduct 56 (Equation 6) <2003JOC8258>. 

Photochemical polymerization of dithiophene 325 in acetonitrile in the presence of CC14 and TBABr leads to a thin film with electrochromic properties in the visible region (94JCS(CC)1911 95SM(69)309). Laser flash photolysis in the presence of CC14 showed absorption at 417 nm due to the radical cation. 

In view of the information on naturally occurring dithiophenes and trithiophenes already available from these sources, this survey emphasizes the occurrence, the biosynthesis, the synthesis, the photophysical and photochemical properties, and especially the biological properties of these molecules. 

Gommers, F.J., J. Barker, and H. Wynberg. Dithiophenes as Singlet Oxygen Sensitizers. Photochem. Photobiol. 35, 615 (1982). 

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