Chiral Carboxyl-Functionalized Covalent Organic Framework for Enantioselective Adsorption of Amino Acids

Combining chiral molecules and covalent organic frameworks (COFs) with ordered pores can result in chiral COFs, which may be employed in the fields of chiral chemistry. In this study, we constructed a novel carboxyl-functionalized COF TpBD-3COOH first and then integrated a chiral molecule, heptakis (6-amino-6-deoxy)-β-CD (Am7CD), into TpBD-3COOH to obtain TpBD-Am7CD. Comparing TpBD-3COOH with TpBD-Am7CD, it could be observed that chiral selectivities improved significantly after decorating TpBD-3COOH with Am7CD in the adsorption experiment. Meanwhile, TpBD-Am7CD exhibited similar chiral selective abilities as the previously reported β-CD COF when it was employed to adsorb amino acid enantiomers, while the content of Am7CD was much less than that in β-CD COF. This indicated that the framework of TpBD-3COOH enhanced the chiral selective ability of Am7CD, which would be a great chiral carrier material for further application. This work provides a new insight for establishing materials for application in the chiral recognition field. Besides, TpBD-Am7CD resulted in an insoluble powder, which endowed this material with the possibility to be an adsorbent and a stationary phase in chromatography.