(602c) One-Pot Synthesis of Ionic Covalent Organic Frameworks Via Menshutkin Reaction

Covalent organic frameworks (COFs) having crystallinity and ionic groups called ionic COFs (iCOFs) have attracted remarkable attraction from the scientific community. The ample ionic groups and adjustable structural chemistry and defined channel facilitate various applications such as separation, energy storage, catalysis and sensing. Despite notable progress made in this research area, the synthesis of iCOFs in one-step is challenging. As of now, the iCOFs especially cationic COFs (cCOFs) have been synthesized either by using ionic monomer or post-modification of pre-synthesized COFs. Herein, we report the one-pot synthesis of cCOFs using neutral monomers 5,10,15,20-tetra(4-pyridyl) porphyrin (TPP) or 5,10,15,20-tetra(4-pyridyl) porphyrinato copper (II) (CuTPP) along with 1,4-bis-bromomethyl-benzene (BBMB) in chloroform via Menshutkin reaction for effective iodine uptake. In the present study, no ionic monomer and post-treatment strategy was followed. It was noticed that, upon increasing the reaction time, the cCOFs were changed their morphology from 2D nanosheet to 1D nanofiber due to the presence of intermolecular forces. We also found that the concentration of copper (II) acetate concentration affects the morphology of the isolated cCOFs. When we prepared the CuTPP with 2.3 equivalents of copper (II) acetate, we ended up with rod-like morphology of cCOFs. This trend was attributed to the formation of a metal-organic framework (MOF) between TPP and copper (II) acetate via a paddlewheel-like complex. Thus, the optimized concentration of 1.2 equivalents of copper (II) acetate led to the formation and 1D nanofiber morphology. Furthermore, the as-synthesized cCOFs exhibited maximum iodine uptake of 3.5 g g^-1. The simulation studies suggested that the presence of the ionic functional group improves iodine uptake by forming I₂Br^- ions.