Direct Ladderization of Cyclooctatetraene-containing, Processable Conjugated Ladder Polymers from Annulated bis-Zirconacyclopentadienes

Conjugated ladder polymers (CLPs) are difficult yet captivating synthetic targets due to their fully unsaturated fused backbones. Inherent challenges associated with their synthesis often lead to low yields, structural defects, and insoluble products. Here a new method to form CLPs is demonstrated, utilizing a high-yielding dimerization of annulated zirconacyclopentadienes to form cyclooctatetraene (COT) monomer units. The resulting COT-containing polymers form rapidly in a single ladderization step from the bis-zirconacyclopentadiene precursors and display molecular weights up to 29.7 kDa. The polymers represent rare examples of CLPs with negatively curved rings, resulting in the observation of unusual properties. The rigid tub-shaped COT units embedded in the backbone imbue the polymers with microporosity, exhibiting BET surface areas up to 555 m2/g. Additionally, the remarkable solubility of these CLPs in organic solvents enables the fabrication of thin films showcasing high dielectric performance with a discharged energy density as high as 6.54 J/cm3 at 650 MV/m