Quater-, quinque-, and sexithiophene organogelators: Unique thermochromism and heating-free sol-gel phase transition

Shin Ichiro Kawano, Norifumi Fujita, Seiji Shinkai

Research output: Contribution to journalArticle

155 Citations (Scopus)

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 languageEnglish
Pages (from-to)4735-4742
Number of pages8
JournalChemistry - A European Journal
Volume11
Issue number16
DOIs
Publication statusPublished - Aug 5 2005

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Sol-gels
Atomic force microscopy
Bearings (structural)
Gels
Phase transitions
Circular dichroism spectroscopy
Derivatives
Heating
Fibers
Ascorbic acid
Ascorbic Acid
Agglomeration
Transmission electron microscopy
Scanning electron microscopy
Molecules
Fluids
sexithiophene

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 journalArticle

Kawano, Shin Ichiro ; Fujita, Norifumi ; Shinkai, Seiji. / Quater-, quinque-, and sexithiophene organogelators : Unique thermochromism and heating-free sol-gel phase transition. In: Chemistry - A European Journal. 2005 ; Vol. 11, No. 16. pp. 4735-4742.
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