Click nanosponge - A novel amine-rich β-cyclodextrin-based crosslinked polymer for heterogeneous catalysis

Cyclodextrin-based nanosponges are promising materials for heterogeneous catalysis due to their inherent synthetic versatility, tunable porosity and nontoxicity. In this work, a primary amine-rich beta-cyclodextrin nano-sponge was synthesized via click imine condensation reaction between 1,6-hexamethylamine-functionalized beta-cyclodextrin (CDAM) and glutaraldehyde (GLT) to afford CDGLAM, in mild conditions. The crosslinked polymer exhibited a BET surface area of 36.39 m2 g-1, an average pore diameter of 3.09 nm (as assessed by the BJH method), and thermal stability up to 253 degrees C. CDGLAM was tested as heterogeneous catalyst for the metal-free Henry and Knoevenagel reactions, between aromatic aldehydes and nitromethane or ethyl cyanoacetate, respectively, affording the products in moderate to very high yields. These results show the ease of preparation of beta-CD-based nanosponges from a green chemistry perspective, as well as their potential for future use in catalytic systems.

Automated summary

A primary amine-rich beta-cyclodextrin nanosponge was synthesized under mild conditions and showed potential as a heterogeneous catalyst for metal-free reactions.