Design of Two‐Dimensional Heteropolyacid‐Covalent Organic Frameworks Composite Materials for Acid Catalysis

Abstract Covalent organic frameworks (COFs) is a rapidly developing field in material chemistry. However, COFs still have very limited applications due to the absence of functional groups. In this work, we demonstrate the efficient way for the synthesis of crystalline composite based on phosphotungstic acid and 2D imine CIN‐1 type of COF. Heteropolyacid behaves as structure directing agent and it is stabilized between the layers of COF. The composite material shows a layered‐sheet arrangement of large imine network layers with sizes up to 1.5 μm. Owing to the strong interaction of heteropolyacid with COF, the resultant material shows high activity and stability with no leaching during acid‐catalyzed esterification reaction.