Dual-Functional Triphenyltriindole "Knitting Polymers" for Efficient Iodine Capture and Zn-I₂ Batteries

This work introduces a class of nitrogen-rich porous polymers synthesized via "knitting polymerization" using a redox-active triphenyltriindole monomer. Two synthetic routes-thermal Friedel-Crafts reaction (TRIPh-d) and solvent-free mechanochemical activation (TRIPh-m) yield polymers with similar chemical structures but markedly different surface areas. Despite this, both materials exhibit exceptional iodine uptake from hexane solution (up to 1.87 g g^-1), placing them among the highest-performing amorphous microporous organic polymers reported to date. The superior adsorption is attributed to the reversible oxidation of triindole units, forming radical cations that enhance iodine capture through electrostatic interactions. Comparative analysis with a truxene-based analog (TX-m) confirms the critical role of nitrogen-rich scaffolds over surface area alone. Beyond iodine sequestration, TRIPh-d also demonstrates outstanding performance as a cathode material in zinc-iodine batteries (ZIBs), delivering a specific capacity of 228 mA h g^-1 at 1 A g^-1, 99% Coulombic efficiency, and 72% capacity retention over 10,000 cycles. This dual functionalitycombining environmental remediation with energy storage-along with the sustainability of the synthesis, positions these redox-active knitting polymers as promising candidates for future applications.