Programmable Diacetylene-Bridged Cyclotetrathiophenes With Nonplanar π-Expanded Skeleton for Electrochemical Sodium...

Fused aromatic ring systems offer flexibility in molecular-level design, facilitating programmable redox activity and exhibiting remarkable energy-storage performance. Nevertheless, the planar backbone structure and strong π-π stacking significantly impede their practical capacity and cycle stability. Herein, we present a novel three-dimensional (3D) polymer, diacetylene-linked cyclic tetrathiophene (3D-PTE-COTh) with a partial crystalline structure, which is based on the thiophene-fused [8]cycloene framework and intramolecular acetylene connecting wires. This construction exploits the electrochemically induced micro-telescopic behavior regulated by Hückel's rule, allowing for dynamic conformational alterations that alleviate π-π stacking effects. Simultaneously, the combination of fused thiophene and graphdiyne-like linkages improves electronic conductivity and introduces a plethora of electron-deficient redox-active sites. As a cathode material, the synergistic sodium storage of the cyclooctatetraene (C₈ ring), ─C≡C─C≡C─ bonds, and fused-thiophene enables 3D-PTE-COTh to achieve a high specific capacity of 347.9 mAh g^-1 at 0.5 A g^-1, thereby presenting new prospects for the design of advanced organic electrode materials.