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

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 pi-electrons within the material (i.e., electrons not engaged in a pi-pi 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. The utilization of the endless stacking hydrogen bonding mode in amides represents a versatile approach for the fabrication of hydrogen-bonded organic frameworks (HOFs). HOFs featuring amide units and derived from tribenzocyclyne exhibit a diversity of supramolecular architectures. They have a high capacity for capturing iodine as well as sensing capability because of their porous nature and the presence of accessible aromatic groups.image