Abstract
Cis-transoidal poly(4‘-ethynylbenzo-15-crown-5) (2) prepared by the polymerization of 4‘-ethynylbenzo-15-crown-5 with Rh(nbd)BPh4 has been used as a thermoresponsive material with a chiral on−off switching property. In the circular dichroism (CD) spectrum of 2 in the presence of the perchloric acid salt of l-phenylglycine (l-Pgly·HClO4) at −30 °C, a large Cotton effect with an intensity of +2.96 × 104 deg cm2 dmol-1 was observed in the range from 300 to 550 nm corresponding to the absorption of the conjugated polymer backbone, indicating that 2 formed the one-handed helical structure triggered by the host−guest complexation with l-Pgly·HClO4. However, the induced CD (ICD) intensity significantly decreased with the increasing temperature and almost completely disappeared at 30 °C or over. Furthermore, an alternate temperature modulation between −30 and 30 °C brought about the reversible on−off switching of the ICD of 2.
Published Version
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