Two-Dimensional Imine-Linked Covalent Organic Frameworks as a Platform for Selective Oxidation of Olefins

Abstract

Two-dimensional imine-linked covalent organic frameworks with hydroxyl groups, TAPT-DHTA-COF HX and TAPT-DHTA-COF DMF, were respectively constructed by the condensation of 1,3,5-tris-(4-aminophenyl)triazine and 2,5-dihydroxyl-terephthalaldehyde under solvothermal and reflux conditions. Both COFs possess excellent thermal stability and a similar eclipsed stacking structure verified by XRD patterns. However, TAPT-DHTA-COF HX presented a larger surface area (2238 m 2 /g) and higher crystallinity than TAPT-DHTA-COF DMF . Significantly, copper ions are efficiently incorporated into the pores of these two COFs via the coordination interaction with hydroxyl groups and imine linkers. The obtained copper-containing COFs ( Cu-COF HX and Cu-COF DMF ) were employed in the selective oxidation of styrene to benzaldehyde. Cu-COF HX with superior surface area (1886 m 2 /g) and pore volume (1.11 cm 3 /g) exhibited excellent catalytic performance and recyclability. This strategy not only provides a convenient approach to design imine-linked 2D COFs with hydroxyl groups, but also develops their novel application for catalysis.