Hydrogen-Bonded Organic Frameworks Based on Endless-Stacked Amides for Iodine Capture and Detection

Abstract

Recently, hydrogen-bonded organic frameworks (HOFs) have emerged as a rapidly advancing class of porous materials with significant potential for applications in the absorption and detection of various chemicals. Here, the unique ability of amide groups to form endless-stacking H-bonds is implemented in the design of HOFs. Starting from benzene-1,3,5-tricarboxamide and amide-containing tribenzocyclynes as foundational building blocks, a diverse range of HOFs featuring 1D, 2D, or 3D hydrogen-bonded frameworks has been synthesized. Among those, all three porous HOFs, HOF_B-Hex, HOF_T-Pr and HOF_T-Hex exhibited permanent porosity, thereby demonstrating the effectiveness of amide-based HOFs strategy. Notably, HOF_T-Hex stands out with a 42% pore volume and an impressive iodine capture efficiency of 6.4 g g−1. The iodine capture capacity is influenced not only by pore volume but also by the presence of accessible π-electrons within the material (i.e., electrons not engaged in a π–π stacking interaction. Furthermore, some of these HOFs exhibited fluorescent responses to iodine positioning them as highly promising materials for both the capture and sensing of iodine.