Hierarchical Bottom-Up Methodology for Integrating Dynamic Ethynylhelicene Oligomers by Nozomi Saito

Author:Nozomi Saito
Language: eng
Format: epub
Publisher: Springer Japan, Tokyo

(M)-bD-4/(P)-bD-5

(M)-bD-4/(P)-D-5

(M)-D-4/(P)-D-5

(M)-D-5/(P)-DF-4

ε365/ε335

0.9

0.82

0.95

0.93

Morphology

Fiber/gel

Fiber/gel

Fiber/gel

Fiber/gel

Bundles

Large amount

Large amount

Small amount

Small amount

Thermal stability

Stable

Stable

Less stable

Stable

Transparency

Turbid

Turbid

Clear

Clear

MGC

1 mM

0.5 mM

0.1 mM

0.1 mM

5.2 Vesicle Formation in Diethyl Ether

Vesicular assembly was observed in diethyl ether, which was different from the fibers/gels in toluene. When solutions (diethyl ether, 1.0 × 10−4 M) were mixed in a 1:1 ratio, the mixtures of all the (M)-bD-4/(P)-bD-5, (M)-bD-4/(P)-D-5, (M)-D-4/(P)-D-5, and (M)-D-5/(P)-DF-4 systems immediately turned deep yellow and semitransparent. Tyndall scattering was observed by passing laser light (532 nm) through the solutions, which indicated the formation of small particles. Soft precipitates, and not gel, appeared and gradually increased in amount.

The CD and UV-Vis spectra of (M)-bD-4 and (P)-bD-5 (diethyl ether, 2.5 × 10−5M, 25 °C) were typical of a double helix and a random coil, respectively, and the calculated spectra showed relatively intense Cotton effects (Fig. 5.5a, top). The CD spectra of a 1:1 mixture of (M)-bD-4/(P)-bD-5 (diethyl ether, total 2.5 × 10−5 M, 25 °C) immediately showed an enhanced Cotton effects, which was different from the calculated spectrum. A steady state was reached after 3 h with a negative maximum at 315 nm and a positive maximum at 370 nm (Fig. 5.5a, top). The UV-Vis spectra also reached a steady state after 3 h, giving an ε 365/ε 335 of 0.78 (Fig. 5.5a, bottom).

Fig. 5.5CD (top) and UV-Vis (bottom) spectra (diethyl ether, total 2.5 × 10−5 M, 25 °C) of 1:1 mixtures of a (M)-bD-4/(P)-bD-5, b (M)-bD-4/(P)-D-5, c (M)-D-4/(P)-D-5, and d (M)-D-5/(P)-DF-4. Calculated spectra obtained by adding the spectra of the components (diethyl ether, 2.5 × 10−5 M, 25 °C) and dividing the total spectra by two are also shown

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