Abstract
New crown-appended cholesterol-based organogelators 1-3, which have one or two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton binding site, and one crown moiety as a cation binding site, were synthesized, and the gelation ability was evaluated in organic solvents. These gelators could gelatinize several organic solvents under 1.0 wt %, indicating that 1 - 3 act as a versatile gelator of various organic solvents. We observed CD spectra of the acetic acid or propionic acid gels of 1-3 to characterize the aggregation mode in the organogel system. In the CD spectrum of the acetic acid gel 1, the positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient into the clockwise direction. On the other hand, propionic acid gels 2 and 3, bearing only one cholesterol, moiety exhibit a negative sign for the first Cotton effect, strongly suggesting that the dipole moments of the azobenzene chromophores orient into the anticlockwise direction. The TEM images of the 1+acetic acid gel resulted in the helical ribbon and tubular structures. Sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out with 1-3 as templates in the gel phase. The silica obtained from the 1+acetic acid gel showed the helical ribbon with 200-1700 nm width and the tubular structure of the silica with constant about 560 nm outer diameter. As far as can be recognized, all the helicity possesses a right-handed helical motif. Since the exciton coupling band of the organogel also shows P (right-handed) helicity, we consider that a microscopic helicity is reflected by a macroscopic helicity. On the other hand, the tubular structure of the silica obtained from the organogels 2 and 3 is somewhat different from that prepared from the organogel 1. The careful examination of SEM and TEM pictures revealed that the tube wall of the silica features a roll-paper-like multilayer structure. Thus, this paper demonstrates successful and rare examples for precise transcription of gel superstructures into inorganic silica materials.
| Original language | English |
|---|---|
| Pages (from-to) | 5307-5313 |
| Number of pages | 7 |
| Journal | Chemistry - A European Journal |
| Volume | 9 |
| Issue number | 21 |
| DOIs | |
| Publication status | Published - Nov 7 2003 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Organic Chemistry
Cite this
Creation of Double Silica Nanotubes by Using Crown-Appended Cholesterol Nanotubes. / Jung, Jong Hwa; Lee, Seok Hoon; Yoo, Jong Shin; Yoshida, Kaname; Shimizu, Toshimi; Shinkai, Seiji.
In: Chemistry - A European Journal, Vol. 9, No. 21, 07.11.2003, p. 5307-5313.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Creation of Double Silica Nanotubes by Using Crown-Appended Cholesterol Nanotubes
AU - Jung, Jong Hwa
AU - Lee, Seok Hoon
AU - Yoo, Jong Shin
AU - Yoshida, Kaname
AU - Shimizu, Toshimi
AU - Shinkai, Seiji
PY - 2003/11/7
Y1 - 2003/11/7
N2 - New crown-appended cholesterol-based organogelators 1-3, which have one or two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton binding site, and one crown moiety as a cation binding site, were synthesized, and the gelation ability was evaluated in organic solvents. These gelators could gelatinize several organic solvents under 1.0 wt %, indicating that 1 - 3 act as a versatile gelator of various organic solvents. We observed CD spectra of the acetic acid or propionic acid gels of 1-3 to characterize the aggregation mode in the organogel system. In the CD spectrum of the acetic acid gel 1, the positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient into the clockwise direction. On the other hand, propionic acid gels 2 and 3, bearing only one cholesterol, moiety exhibit a negative sign for the first Cotton effect, strongly suggesting that the dipole moments of the azobenzene chromophores orient into the anticlockwise direction. The TEM images of the 1+acetic acid gel resulted in the helical ribbon and tubular structures. Sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out with 1-3 as templates in the gel phase. The silica obtained from the 1+acetic acid gel showed the helical ribbon with 200-1700 nm width and the tubular structure of the silica with constant about 560 nm outer diameter. As far as can be recognized, all the helicity possesses a right-handed helical motif. Since the exciton coupling band of the organogel also shows P (right-handed) helicity, we consider that a microscopic helicity is reflected by a macroscopic helicity. On the other hand, the tubular structure of the silica obtained from the organogels 2 and 3 is somewhat different from that prepared from the organogel 1. The careful examination of SEM and TEM pictures revealed that the tube wall of the silica features a roll-paper-like multilayer structure. Thus, this paper demonstrates successful and rare examples for precise transcription of gel superstructures into inorganic silica materials.
AB - New crown-appended cholesterol-based organogelators 1-3, which have one or two cholesterol skeletons as a chiral aggregate-forming site, two amino groups as an acidic proton binding site, and one crown moiety as a cation binding site, were synthesized, and the gelation ability was evaluated in organic solvents. These gelators could gelatinize several organic solvents under 1.0 wt %, indicating that 1 - 3 act as a versatile gelator of various organic solvents. We observed CD spectra of the acetic acid or propionic acid gels of 1-3 to characterize the aggregation mode in the organogel system. In the CD spectrum of the acetic acid gel 1, the positive sign for the first Cotton effect indicates that the dipole moments of azobenzene chromophores tend to orient into the clockwise direction. On the other hand, propionic acid gels 2 and 3, bearing only one cholesterol, moiety exhibit a negative sign for the first Cotton effect, strongly suggesting that the dipole moments of the azobenzene chromophores orient into the anticlockwise direction. The TEM images of the 1+acetic acid gel resulted in the helical ribbon and tubular structures. Sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out with 1-3 as templates in the gel phase. The silica obtained from the 1+acetic acid gel showed the helical ribbon with 200-1700 nm width and the tubular structure of the silica with constant about 560 nm outer diameter. As far as can be recognized, all the helicity possesses a right-handed helical motif. Since the exciton coupling band of the organogel also shows P (right-handed) helicity, we consider that a microscopic helicity is reflected by a macroscopic helicity. On the other hand, the tubular structure of the silica obtained from the organogels 2 and 3 is somewhat different from that prepared from the organogel 1. The careful examination of SEM and TEM pictures revealed that the tube wall of the silica features a roll-paper-like multilayer structure. Thus, this paper demonstrates successful and rare examples for precise transcription of gel superstructures into inorganic silica materials.
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U2 - 10.1002/chem.200305008
DO - 10.1002/chem.200305008
M3 - Article
C2 - 14613140
AN - SCOPUS:0344065560
VL - 9
SP - 5307
EP - 5313
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 21
ER -