Task-specific synthesis of novel indole-based porous organic polymers for carbon dioxide adsorption and iodine uptake

Two novel indole-based porous organic polymers, InPhHCP-7 and InMelPOP, were synthesised using Friedel–Crafts alkylation and acetal reactions respectively. InPhHCP-7 was specifically designed for CO2 adsorption, whereas InMelPOP was developed for the removal of iodine species from aqueous solution. Under a pure dry CO2 atmosphere, the CO2 adsorption capacity of InPhHCP-7 reached 2.28 mmol g−1 at 25°C and 100 kPa, with negligible performance degradation over three adsorption–desorption cycles. The adsorption mechanism is predominantly physical in nature. For InMelPOP, 1.978 g g−1 of I2 adsorption capacity was achieved when 50.0 mg of the material was soaked in 3 mL of 1 × 105 mg L−1 KI3 aqueous solution for 48 h. The I2 adsorption capacity could still retain 1.620 g g−1 after three cycles. The iodine adsorption process involves both physical and chemical interactions. Both materials exhibit superior adsorption performance compared to most previously reported porous organic polymers. Their adsorption performance is governed by the synergistic interplay between hierarchical pore architecture and the presence of multiple active adsorption sites. This study provides both experimental evidence and theoretical insights for the efficient capture of CO2 and iodine species.