Amide-Pyridine Hydrogen-Bonded Organic Framework for Iodine Capture

Abstract

Despite the rapid growth of hydrogen-bonded organic frameworks (HOFs), developing HOF adsorbents that integrate cost-effectiveness, environmental sustainability, and high uptake capacity remains a challenge. Herein, we report an amide-pyridine-based hydrogen-bonded organic framework (TPADPy-HOF) iodine adsorbent derived from the self-assembly of N1,N4-di(pyridin-4-yl)terephthalamide, which successfully reconciled the trade-off between efficient synthesis, ecological sustainability, and robust adsorption functionality. Relying on the cooperative effects of amide hydrogen bonds and π−π stacking, the obtained TPADPy-HOF featured robust crystallinity and uniform 1D channels with a pore size of around 5.874 Å × 6.027 Å, which collectively underpinned its outstanding adsorption performance toward iodine vapor and iodine species in both water and seawater. Its gaseous iodine adsorption capacity reached 5.2 g g−1, while the adsorption capacities for I2 and I3− in liquid media were 0.454 g g−1 and 0.685 g g−1, respectively, and the removal efficiency was as high as 99%. Meanwhile, the TPADPy-HOF adsorbent possessed good stability, regenerability, and recyclability, underscoring its long-term sustainability for practical applications. Mechanistic investigations revealed that the superior iodine adsorption performance of the TPADPy-HOF originated from the synergistic effect of supramolecular interactions between iodine and the heteroatoms in amide/pyridine groups, coupled with charge-transfer interactions stemming from its electron-rich architecture. These findings make the TPADPy-HOF a highly promising material for iodine pollution treatment and iodine resource recovery in seawater.