Three-Step Synthesis of a Less-Aggregated Water-Soluble Poly(p‑phenylene ethynylene) with Meta Side Chains via Palladium/Norbornene Cooperative Catalysis

A three-step preparation of a highly water-soluble poly­(p-phenylene ethynylene) (PPE) from commercially available starting materials is disclosed. The palladium/norbornene-catalyzed AB–C-type polymerization has been developed, which enables installation of two piperazine meta side chains concurrently with the construction of the PPE backbone. The capability for double protonation of the piperazine moiety improves water solubility of this material. Compared to the PPE containing para side chains, the meta side chains reduce interchain aggregation and significantly enhance solubility and fluorescent quantum yields of the polymer.

本研究报道了一条以市售原料为起始底物，经三步反应制备高水溶性聚(对亚苯基亚乙炔基)（poly(p-phenylene ethynylene), PPE）的合成路线。本工作开发了钯/降冰片烯催化的AB-C型聚合体系，该体系可在构建PPE主链的同时，同步引入两个间位哌嗪侧链。哌嗪基团的双重质子化能力可有效改善该聚合物的水溶性。与带有对位侧链的PPE相比，间位侧链能够降低分子链间聚集，显著提升该聚合物的溶解性与荧光量子产率。