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The enantioselective synthesis of a novel photochronic helicenoid diarylethene (R)-1-[1-(1-methoxymethomyethyl)-2-naphtho[2,1-b]thienyl]-2-(2,4,5-trimethyl-3-thienyl)hexafluorocyclopentene is reported. The product showed highly diastereoselective photocyclization (90% de) and a large change (950 degree) in the specific optical rotation value at 633 nm upon ultraviolet (UV) light irradiation in ethyl acetate.

The synthesis, photochromism, and optical properties of a chiral heliconoid diarylethene that shows a large change in specific optical rotation induced by photochromism is reported. The diarylethene possessing one [4]thiaheterohelicene and one benzothiophene with a chiral methoxymethoxyethyl group on its C-3 position was proved to work as a switch of specific optical rotation at a wavelength at which both colored and colorless forms have no absorption in solution.

Photosublimation of the photoproduct of ethyl-4-formyl-1,3-dimethylpyrazole-5-carboxylate(EFDPC) is studied at room temperature and normal atmospheric pressure. It is observed that the unprecedented localized heating due to absorbed photon energy exceeds the activation energy for sublimation resulting in evaporation of the molecules from the substrate surface.

Nine 1-[2-(1-substituted)ethyl-3-benzothienyl]-2-(2-methyl-3-benzothienyl)hexafluorocyclopentenes(4-substituted benzoyloxy, N-arylcarbamoyloxy, and aryloxycarbonyloxy) were synthesized. Upon UV irradiation, they showed diastereoselective photochromic ring closure.

A diarylethene possessing one [4]thiaheterohelicene and one benzothiophene, the latter with a chiral methoxymethoxyethyl group on its C-3 position, was proved to work as a switch of specific optical rotation at a wavelength at which both colored and colorless forms have no absorption in solution. The difference of the specific optical rotation was 13000 between the open form and the photostationary state. The specific optical rotation of one of the isolated optically active major colored forms was -4680°. The conversion to the colored form was 64%, and the diastereomeric excess of photocyclization was 47%. [ABSTRACT FROM AUTHOR]

A novel photochromic helicenoid diarylethene (R)-1-[1-(1-methoxymethoxyethyl)-2-naphtho[2,1-bjthienyl]-2-(2,4,5-trimethyl-3-thienyl)hexafluorocyclopentene was synthesized enantioselectively. It showed highly diastereoselective photocyclization (90% de) and a large change (9500) in the specific optical rotation value at 633 nm upon UV light irradiation in ethyl acetate. [ABSTRACT FROM AUTHOR]