Versatile and Facile Preparation of Chiral Polyacetylene-Based Gel Film and Organic−Inorganic Composites

Abstract

A new SiH-containing chiral polyacetylene, poly[p-[{(S)-2-methylbutyl}methylsilyl]-phenylacetylene] (1), with a moderate molecular weight (Mw 4.4 × 104; Mw/Mn 2.4) was obtained with [RhCl(nbd)]2−NEt3 catalyst. IR and 1H NMR studies revealed that the SiH group in 1 remains intact, with no side reactions such as hydrosilylation and hydrolysis. Furthermore, 1 readily turned into a transparent gel film with Si−O−Si linkages simply by standing in air at room temperature. The polymer 1 exhibited a quite large optical rotation ([α]D = 600°, c = 0.12 g/dL in toluene at 25 °C), corresponding to large molar ellipticities ([θ]ext = −5.1 × 103 deg·cm2·dmol-1 at 326 nm and 4.7 × 103 deg·cm2·dmol-1 at 371 nm). The CD intensity of the gel film scarcely changed in the range from 25 to 85 °C, presumably due to Si−O−Si cross-linking. Moreover, organic−inorganic composite materials were easily obtained by stirring inorganic particles such as titania and silica gel in the polymer solution. The prepared composites were charac...