26 Interplay of Photoisomerization and Phase Transition Events …
455
activity and reassembling of molecules are predicted. Correspondingly, our system
was designed so that photoisomerization of the azobenzene derivative would trigger
realignment of the fatty acid molecules to modulate the kinetics of the photoisomerization events. A helical assembly of oleic acid (1) and an amphiphilic azobenzene
(2) never showed repetitive motion under steady light irradiation [60]. Rather, a
multi-step recoiling motion was observed involving acid-dissociation behavior of a
carboxyl group [61]. Vesicular, tubular, and block-like assemblies also did not exhibit
repetitive dynamics [60]. However, we eventually observed that plate-like assemblies
of 1 and 2 exhibited repetitive flips under steady blue-light irradiation (Fig. 26.5)
[53].
Fig. 26.5 Self-continuous flipping motion observed for a co-assembly of oleic acid (1) and an
azobenzene derivative (2) by Ikegami in 2016 [53]. a The chemical structures of 1 and 2 are shown
along with the photochromism step of 2. b A generalized illustration of the flipping motion of
azobenzene with states A-C and A and B indicated. c–j Video imaging of the flipping motion of
a 1 crystal detected with a differential interference contrast microscope equipped with a mercury
lamp unit (λ irr = 435 nm). The left side of the crystal exhibited alternating flips (cyclically around
A, B, and C), while the right side of the crystal exhibited singular flips between the A and B states.
A video is available from the website listed in Ref. [53]
455
activity and reassembling of molecules are predicted. Correspondingly, our system
was designed so that photoisomerization of the azobenzene derivative would trigger
realignment of the fatty acid molecules to modulate the kinetics of the photoisomerization events. A helical assembly of oleic acid (1) and an amphiphilic azobenzene
(2) never showed repetitive motion under steady light irradiation [60]. Rather, a
multi-step recoiling motion was observed involving acid-dissociation behavior of a
carboxyl group [61]. Vesicular, tubular, and block-like assemblies also did not exhibit
repetitive dynamics [60]. However, we eventually observed that plate-like assemblies
of 1 and 2 exhibited repetitive flips under steady blue-light irradiation (Fig. 26.5)
[53].
Fig. 26.5 Self-continuous flipping motion observed for a co-assembly of oleic acid (1) and an
azobenzene derivative (2) by Ikegami in 2016 [53]. a The chemical structures of 1 and 2 are shown
along with the photochromism step of 2. b A generalized illustration of the flipping motion of
azobenzene with states A-C and A and B indicated. c–j Video imaging of the flipping motion of
a 1 crystal detected with a differential interference contrast microscope equipped with a mercury
lamp unit (λ irr = 435 nm). The left side of the crystal exhibited alternating flips (cyclically around
A, B, and C), while the right side of the crystal exhibited singular flips between the A and B states.
A video is available from the website listed in Ref. [53]