Mixed-linker approach employing a flexible monomer for constructing highly crystalline multiple-component covalent...

Covalent organic frameworks (COFs) are emerging as promising materials across diverse fields, including catalysis, gas storage, water harvesting, and energy storage. Traditionally, COF development relies on the two-component synthesis approach, where two organic monomers with specific reactive sites are strategically combined to form well-ordered frameworks in specific topologies. Although this approach has been effective, it inherently restricts the structural diversity of COFs unless new linkers are introduced, limiting the range of properties achievable. A more flexible and increasingly popular approach in COF synthesis is the use of multicomponent reactions and mixed linker strategies, incorporating three or more organic monomers into a single COF. While researchers have primarily focused on reaction pathways for synthesizing multiple-component COFs, one area that remains relatively underexplored is the use of flexible linkers within these strategies. This study addresses this gap by selecting a flexible amine linker and combining it with four distinct aldehyde linkers in various combinations. This approach allows us to successfully synthesize fifteen different highly crystalline COF materials, including two-component, along with three, four, and five-component COFs. A comparative study of photocatalytic performance between the two-component with the five-component COF demonstrated that increased structural functionalities leads to higher surface area, enhanced visible-light absorption, and consequently enhanced photocatalytic activity in the oxidative conversion of aryl phenylboronic acid to phenol.