Abstract
A series of quater-, quinque-, and sexithiophene derivatives bearing two cholesteryl groups at the α-position, which are abbreviated as 4T-(chol)2, 5T-(chol)2, and 6T-(chol)2, respectively, have been synthesized. It has been found that these oligothiophene derivatives act as excellent organogelators for various organic fluids and show the unique thermochromic behaviors through the sol-gel phase transition. It was shown on the basis of extensive investigations, performed with UV-visible spectroscopy, circular dichroism (CD), transmission electron" microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), that these gelators self-assemble into the one-dimensional structures in the organogels, in which the π-block moieties of the oligothiophenes are stacked in an H-aggregation mode. Surprisingly, an AFM image shows that 4T-(chol) 2 forms unimolecular fibers in a left-handed helical sense, whereby one pitch of the helical fiber is constructed by 400-540 4T-(chol)2, molecules. Very interestingly, the conformational change in the oligothiophene moieties can be visually detected: for example, 6T-(chol)2 shows a specific absorption maximum in the gel (λmax = 389 nm) and in the solution (λmax = 439 nm). In addition, a sol-gel phase transition of the 6T-(chol)2 gel was implemented by addition of oxidizing and reducing reagents such as FeCl3 and ascorbic acid, respectively. The stimuli-responsive functionality of the oligothiophene-based organogels makes them promising candidates for switchable opto- and electronic soft materials.
| Original language | English |
|---|---|
| Pages (from-to) | 4735-4742 |
| Number of pages | 8 |
| Journal | Chemistry - A European Journal |
| Volume | 11 |
| Issue number | 16 |
| DOIs | |
| Publication status | Published - Aug 5 2005 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Organic Chemistry
Cite this
Quater-, quinque-, and sexithiophene organogelators : Unique thermochromism and heating-free sol-gel phase transition. / Kawano, Shin Ichiro; Fujita, Norifumi; Shinkai, Seiji.
In: Chemistry - A European Journal, Vol. 11, No. 16, 05.08.2005, p. 4735-4742.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Quater-, quinque-, and sexithiophene organogelators
T2 - Unique thermochromism and heating-free sol-gel phase transition
AU - Kawano, Shin Ichiro
AU - Fujita, Norifumi
AU - Shinkai, Seiji
PY - 2005/8/5
Y1 - 2005/8/5
N2 - A series of quater-, quinque-, and sexithiophene derivatives bearing two cholesteryl groups at the α-position, which are abbreviated as 4T-(chol)2, 5T-(chol)2, and 6T-(chol)2, respectively, have been synthesized. It has been found that these oligothiophene derivatives act as excellent organogelators for various organic fluids and show the unique thermochromic behaviors through the sol-gel phase transition. It was shown on the basis of extensive investigations, performed with UV-visible spectroscopy, circular dichroism (CD), transmission electron" microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), that these gelators self-assemble into the one-dimensional structures in the organogels, in which the π-block moieties of the oligothiophenes are stacked in an H-aggregation mode. Surprisingly, an AFM image shows that 4T-(chol) 2 forms unimolecular fibers in a left-handed helical sense, whereby one pitch of the helical fiber is constructed by 400-540 4T-(chol)2, molecules. Very interestingly, the conformational change in the oligothiophene moieties can be visually detected: for example, 6T-(chol)2 shows a specific absorption maximum in the gel (λmax = 389 nm) and in the solution (λmax = 439 nm). In addition, a sol-gel phase transition of the 6T-(chol)2 gel was implemented by addition of oxidizing and reducing reagents such as FeCl3 and ascorbic acid, respectively. The stimuli-responsive functionality of the oligothiophene-based organogels makes them promising candidates for switchable opto- and electronic soft materials.
AB - A series of quater-, quinque-, and sexithiophene derivatives bearing two cholesteryl groups at the α-position, which are abbreviated as 4T-(chol)2, 5T-(chol)2, and 6T-(chol)2, respectively, have been synthesized. It has been found that these oligothiophene derivatives act as excellent organogelators for various organic fluids and show the unique thermochromic behaviors through the sol-gel phase transition. It was shown on the basis of extensive investigations, performed with UV-visible spectroscopy, circular dichroism (CD), transmission electron" microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), that these gelators self-assemble into the one-dimensional structures in the organogels, in which the π-block moieties of the oligothiophenes are stacked in an H-aggregation mode. Surprisingly, an AFM image shows that 4T-(chol) 2 forms unimolecular fibers in a left-handed helical sense, whereby one pitch of the helical fiber is constructed by 400-540 4T-(chol)2, molecules. Very interestingly, the conformational change in the oligothiophene moieties can be visually detected: for example, 6T-(chol)2 shows a specific absorption maximum in the gel (λmax = 389 nm) and in the solution (λmax = 439 nm). In addition, a sol-gel phase transition of the 6T-(chol)2 gel was implemented by addition of oxidizing and reducing reagents such as FeCl3 and ascorbic acid, respectively. The stimuli-responsive functionality of the oligothiophene-based organogels makes them promising candidates for switchable opto- and electronic soft materials.
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UR - http://www.scopus.com/inward/citedby.url?scp=23744457908&partnerID=8YFLogxK
U2 - 10.1002/chem.200500274
DO - 10.1002/chem.200500274
M3 - Article
C2 - 15912544
AN - SCOPUS:23744457908
VL - 11
SP - 4735
EP - 4742
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 16
ER -