Simultaneous construction of two linkages for the on-surface synthesis of imine-boroxine hybrid covalent organic frameworks

Chem Sci. 2017 Mar 1;8(3):2169-2174. doi: 10.1039/c6sc03590f. Epub 2016 Nov 30.

Abstract

The orthogonality between the Schiff base reaction and the boronic acid dehydration reaction is explored during the on-surface synthesis process. By activating the above two reactions in one-step and employing asymmetrical substituted monomers and the 3-fold symmetric monomer 1,3,5-tris(4-aminophenyl)benzene (TAPB), highly ordered imine-boroxine hybrid single-layered covalent organic frameworks (sCOFs) have been successfully constructed on HOPG by a gas-solid interface reaction method and characterized by scanning tunnelling microscopy (STM). In particular, the reaction between the meta-substituted monomer and TAPB generates sCOFB with a windmill structure, which is the first sCOF with surface chirality so far reported. The demonstration of the one-step synthesis of multiple linkages to form sCOFs can further enlarge the sCOF family and expand the design routes for functional 2D organic nanomaterials.