Room‐Temperature Synthesis of Covalent Organic Frameworks with a Boronic Ester Linkage at the Liquid/Solid Interface

Abstract With various prospected applications in the field of nanoelectronics and catalysis, on‐surface synthesis of single‐layer covalent organic frameworks (surface COFs) with designable structures and properties have attracted enormous interest. Herein, we report on a scanning tunneling microscopic investigation of the surface‐confined synthesis of a covalently bonded boronic ester network directly at the octanoic acid/ highly oriented pyrolytic graphite(HOPG) interface under room temperature. The dynamic reaction process was investigated in detail. STM results indicate that the surface networks undergo structural evolution from a hybrid covalent/noncovalent multiwall porous network to single‐wall hexagonal COF with the decrease of monomer concentration. Further experimental observation disclosed that the boronic ester‐linked system is sensitive to instantaneous voltage pulses and the stimulation of the STM tip. In addition, the 1H NMR spectra has further confirmed that the surface and octanoic acid may play important roles in promoting the reaction between 4,4′‐phenylazobenzoyl diboronic acid (ABBA) and 2,3,6,7,10,11‐hexahydroxytriphenylene (HHTP) building units.