A Flexible Hydrogen‐Bonded Organic Framework Constructed from a Tetrabenzaldehyde with a Carbazole N−H Binding Site for the Highly Selective Recognition and Separation of Acetone

Abstract Rational design of hydrogen‐bonded organic frameworks (HOFs) with multiple functionalities is highly sought after but challenging. Herein, we report a multifunctional HOF ( HOF‐FJU‐2 ) built from 4,4′,4′′,4′′′‐(9H‐carbazole‐1,3,6,8‐tetrayl)tetrabenzaldehyde molecule with tetrabenzaldeyde for their H bonding interactions and carbazole N−H site for its specific recognition of small molecules. The Lewis acid N−H sites allow HOF‐FJU‐2 facilely separate acetone from its mixture with another solvent like methanol with smaller p K a value. The donor (D)‐π‐acceptor (A) aromatic nature of the organic building molecule endows this HOF with solvent dependent luminescent/chromic properties, so the column acetone/methanol separation on HOF‐FJU‐2 can be readily visualized.