Photochromic C2-Symmetric Chiral Diarylethene: From the Initial State to the Final State

Abstract

The behavior of 1,2-bis[(R)-2-(1-methoxymethoxyethyl)-3-benzo[b]thienyl] hexafluorocyclopentene before and upon UV irradiation and during thermal evolution of the photoirradiated solution has been thoroughly investigated by multinuclear NMR spectroscopy. A dynamic NMR study of the initial state was performed, providing a detailed description of the perceived conformational processes in the system. Before irradiation, three open conformations are in equilibrium, whereas UV irradiation generated the two expected cyclized diastereomers. The minor diastereomer was thermally less stable than the major one, thus leading to an unexpected increase in the diastereoselectivity when raising the photoirradiation temperature. In addition, a long thermal evolution induced slow rearrangement of the stable diastereomer into byproducts that were identified.

Ring opening/closure reactions of novel diheteroarylethenes derivatives. Solvent effects

“…The cyclized products generated by the conrotatory concerted process would have the methyl groups in the trans geometry as depicted in the Scheme , where the benzotiophene moieties are not in the plane of the cycloethene. It is worthwhile mentioning that the same trans geometry has been reported in another two recent studies with photocromic diarylethene derivatives bearing both benzothiophene moieties, as in the present work …”

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

“…The de values and the conversion ratio to the closed-ring isomers are listed in Table 8. 185,186 The system was further improved by replacing two MOMO groups with two (R)-pentafluoropropanoyloxyethyl groups 107 (Scheme 18), in which diastereoselective photocyclization reaction with >99% de was observed at room temperature. 187 Branda and co-workers 188 prepared compound 108 (Scheme 19), which has chiral substituents in the benzothiophene aryl groups.…”

Enabling Light Work in Helical Self-Assembly for Dynamic Amplification of Chirality with Photoreversibility

“…Particularly, perylene bisimides 18,19 and naphthalene diimides 20,21 are exploited as fluorescent building blocks in construction of these thermodynamically helical nanostructures. Photochromic diarylethenes (DAEs) have also attracted much attention since their chemical and physical properties are reversibly controllable with photo-irradiation [22][23][24] , especially for their functional switching characteristics [25][26][27][28][29][30][31] , such as the photoresponsive helical gel 13,32 and light-driven self-assembly 33,34 . However, the dynamic photoreversibility with modulation of amplified chirality, morphology as well as fluorescence between two thermally stable states are still remaining challenges.…”