Selective Adsorption\nof <i>p</i>‑Xylene\nfrom Xylene Isomers with Self-Adaptive Hydrogen-Bonded Organic Frameworks

The xylenes play an important role in modern industry\nand are mainly\nproduced in the petrochemical industry. However, the selective adsorption\nand separation of xylene isomers are challenging due to their similar\nmolecular sizes and boiling points. In this study, a flexible molecule,\nCHTA, was utilized as a host to construct a host–guest inclusion\ncomplex with xylene isomers, exhibiting self-adaptive structural behavior.\nRemarkably, para-xylene (pX) preferentially crystallizes with CHTA\nin a ternary xylene mixture, forming a pX-solvated structure. After\ndesolvation, the resulting porous hydrogen-bonded organic framework\n(HOF) features a 1D channel, achieving selective pX adsorption from\nthe simulated naphtha solution at a capacity of 103 mg/g. Even at\na low concentration of pX (1%) in xylene isomers, the specific structure\nwith pX occupancy in the channel is formed. The exceptional pX selective\ncocrystallization with CHTA and adsorption with desolvated HOFs enhance\nthe development of pX adsorbents and extend the potential applications\nof HOFs.