Gelation of Metalloporphyrin-Based Conjugated Microporous Polymers by Oxidative Homocoupling of Terminal Alkynes

Abstract

A Pd(II)/Cu(I) cocatalyzed homocoupling reaction of terminal alkynes to diynes was used to synthesize conjugated polymer organogels with tetragonal topological frameworks consisting of Zn-porphyrin units as nodes and diynes as struts. This material appears fibrous with a micrometer length, possesses outstanding elastic properties, and could be organized into desired modules. Upon drying, the transformed xerogels afford superior thermal stability and microporosity, implying that they are supported by conjugated microporous polymer (CMP) skeletons at the molecular level. The microporosity of CMP-structured xerogels could be adjusted by varying the monomer concentrations, reaction temperatures and solvent species. The notable narrowed pore size distribution is achieved under optimal conditions, which results in CMP-supported xerogels outperforming the most reported CMPs, although the networks are still amorphous in nature. By following the same synthesis route, for the first time, the interpenetrating polymer network organogels were prepared by forming two CMP components sequentially in a temperature-controlled manner and in one pot. This provides an unprecedented combination of multiple interwoven CMP modules whose functions could be assembled synergistically for prospective broader applications.