Synthesis and photochromism of 1,2-bis(5-aryl-2-phenylethynylthien-3-yl)hexafluorocyclopentene derivatives

Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes

“…An equilibrium mixture of two conformers (i.e., parallel and antiparallel) exists for DTEs in solution. In addition, the cycloreversion quantum yield for 1c was three fold higher than the symmetrical dodecyl derivative (i.e., ϕ c→o = 0.13 ± 0.01 23 ) and similar to the parent phenylethynyl derivative without alkyl substitution (i.e., ϕ c→o = 0.44 ± 0.02 23 ). 15 Consequently, the cyclization quantum yield is dependent on the ratio of the conformations.…”

“…Upon irradiation with UV light, a pale yellow solution of 1o turned blue and an increase in absorbance was observed at 585 nm with a concomitant decrease at 310 nm ( Fig. 23 The conversion efficiency for 3o was moderately higher with respect to 1 and 2. This new absorption band in the visible region represents the formation of the closed-ring isomer 1c.…”

“…23 For this reason, we used a regioselective approach that introduces functional groups at periphery of the thiophene prior to the introduction of the alkynyl substituents. 23 For this reason, we used a regioselective approach that introduces functional groups at periphery of the thiophene prior to the introduction of the alkynyl substituents.…”

“…23 Briefly, the absorbance of the solution containing A540 was matched to a solution containing the DTE (i.e., 1-3). The procedures used to determine the quantum yields of DTEs have been previously described in detail.…”

“…When these vesicles, loaded with potassium ions, were exposed to UV light, a trans to cis isomerization was observed but ion permeabilities only increased at temperatures approaching the phase transition temperature of DHP. Consequently, the goals of this paper are to report on the synthesis of three new amphiphilic DTEs (Chart 1), two of which integrate bulkier phenylethynyl substituents that undergo larger changes in molecular geometry upon photoisomerization, 22,23 to characterize their photochromic reactivity, to integrate them into four lipid systems of varying lamellar phase, and to examine their photocontrol of ion permeability through a bilayer membrane using a ratiometric fluorescence assay. Interestingly, a decrease in ion permeability was observed upon photoisomerization from the closed-ring spiro isomer to the open-ring merocyanine isomer.…”