Photoinduced transformations of 3,3′-diethylthiacarbocyanine in water in the presence of 9-anthracene carboxylic acid as sensitizer: the influence of cucurbit[7]uril

The effect of cucurbit[7]uril (CB7) on photo induced transformations of cationic dye 3,3′-diethylthiacarbocyanine iodide (Dye + ) in water in the presence of 9-anthracene carb oxylic acid as photosensitizer was studied by nanosecond laser photolysis. Sensitized photoexcitation of Dye + leads to population of the triplet level of the dye. The photoisomerization proceeds via the formation of an intermediate “perpendicular” form of the dye molecule characterized by two absorption bands, as follows from the results of quantum chemical calculations. The presence of CB7 in the dye solution leads to an increase in the lifetime of triplet molecules and in the yield of the diradical cation as a result of dimerization of the dye molecules.