Synthesis of amphiphilic asymmetrical dithienylethenes with aryl groups at the reactive carbons

Abstract

A synthetic route for the preparation of amphiphilic asymmetrical dithienylethenes that incorporate methyl groups at the 4- and 4′-positions and an aryl group at one of the reactive carbons has been developed. The presence of a bulky aryl substituent ensures a relatively large change in molecular geometry upon photoisomerization, whereas the presence of methyl groups provide enhanced photostability. Notably, a substituent effect was systematically revealed en route to the preparation of the dithienylethene precursors. In particular, this formal substitution reaction was significantly inhibited due to steric hindrance, stemming from the presence of aryl and methyl groups at the alpha positions of the preformed thienyl carbanionic carbon, and an aryl group on the monosubstituted perfluorocyclopentene derivative.

Spiropyran/Merocyanine Amphiphile in Various Solvents: A Joint Experimental–Theoretical Approach to Photophysical Properties and Self-Assembly

“…The moieties that are utilized to render amphiphiles the photoresponsive nature are azobenzene [3][4][5][6], stilbene [7][8][9][10][11], dithienylethene [12][13][14] and spiropyran [15][16][17][18], to name a few [2]. Such amphiphiles have exhibited, for example, (i) smart principles for the dynamic control of surface tension of aqueous solutions [19], (ii) phenomenon of the light-driven diffusioosmosis upon which one can remove, gather or pattern a particle assembly at a solid-liquid interface [20], (iii) the photo-controlled stability and breakage of foams [21,22], (iv) new macroscopic functions such as liquid droplet transport [23] and bubble manipulation [15], (v) photoswitchable catalytic properties [24], (vi) photochemical OFF/ON cytotoxicity switching [25], etc.…”