Pressure-inducedcistotransisomerization of poly(ortho- andpara-methoxyphenylacetylene)s prepared by [Rh(norbornadiene)Cl]2 catalyst. A Raman, UV, and ESR study

Abstract

The stereospecific polymerization of o- and p-methoxyphenylacetylenes (MOPAs) with [Rh(norbornadiene)Cl]2 as a catalyst in the presence of an organic base (triethylamine) at 30°C is reported, together with the detailed characterization using resonance Raman, diffuse reflection UV, and ESR spectroscopic methods. The resulting polymers were shown to selectively have a cis-transoid form. It was found, interestingly, that the resultant aromatic polyacetylenes in the cis form are easily isomerized to those in the trans form when a pressure of ca. 100∼200 kg/cm2 was exerted on the solid polymers at room temperature.