Locking of CO ₂ in a Bioinspired Porous-Organic-Polymeric Prison: Impact of Aliphatic Odd–Even Linker Combination

The critical need for better sorbents for CO2 capture and separation (CCS) is at the forefront of the current research scenario, which is addressed here by synthesizing allomelanin-inspired porous organic polymers (POPs) LPOP-n (n = 1–5). An investigation into the effect of different linkers on CO2 adsorption revealed an interesting performance trend, with LPOP-2 showing the highest CO2 uptake, 3.50 and 3.02 mmol/g at 273 and 298 K, respectively, with impressive CO2/N2 selectivity. Moreover, a dynamic breakthrough experiment revealed a longer breakthrough time for CO2 than that for N2, verifying the feasibility of LPOP-2 for its practical application in the CCS process. Density functional theory (DFT) calculations indicated that noncovalent interactions (NCIs), like π-quadrupole interaction and H-bonding, were crucial in dictating the varying CO2 adsorption behaviors across the LPOP-n series. This work underscores how simple materials originating from biologically active units can produce biocompatible materials for gas adsorption and separation applications.