Hydrogen-Bonded Organic Framework for Fluorescence-Guided Toluene/Methylcyclohexane Separation

The efficient separation of a toluene (Tol) and methylcyclohexane (MCH) mixture is a valuable but challenging process in industrial production. Hydrogen-bonded organic frameworks (HOFs) stand out among many porous materials and have emerged as promising porous materials for liquid separation. In this study, a tetradentate thieno[3,2-b]thiophene derivative (CN4TT) was prepared, and a HOF (HOF-TT-1) was synthesized via a solvothermal method. After heating to remove the solvent from the pores (HOF-TT-1a), its fluorescence remarkably changed from its original cyan to blue. The material was utilized to separate a mixture of Tol and MCH, and it was observed to have higher toluene adsorption and to revert to cyan fluorescence after adsorption. Additionally, the material exhibited thermal and acid–base stability, and the adsorption efficiency remained above 89% after five adsorption cycles, demonstrating a strong regenerative ability.