Flexible phosphonium and sulfonate pair-to-pair self-assembled ionic organic single crystals for iodine capture

Abstract

In this work, four flexible chain phosphonium-based ionic organic single crystals (IOCs) are firstly facile prepared by pair-to-pair ionic self-assembly of phosphonium salts and sulfonic acids (salts) under mild conditions. Their structures, morphology, stability, and surface areas are characterized in detail. Featuring a wealth of sulfonate and phenyl groups as powerful active sites for iodine adsorption, these materials exhibit considerable capture capacities. An in-depth investigation of the adsorption mechanism reveals that iodine adsorption on these materials occurs in three distinct states (I2, I3-, and I5-) and follows a mixed-mode adsorption process, involving both physical and chemical interactions. Consequently, this study not only presents a new kind of single crystalline materials based on flexible phosphonium and sulfonic anionic pairs, but also significantly hint the application possibility of this kind of IOCs in some other fields.